Dissertations / Theses: 'Volatile fatty acids'

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Abouzreba, Salem Ali. "Volatile fatty acids in the ambient atmosphere." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388115.

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Ghimire, Sandip. "Volatile Fatty Acid Production in Ruminants." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/75306.

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Volatile fatty acids (VFA) are important products of ruminal fermentation. The VFA are not only the major source of energy to the ruminant animals but also influence methane production in the rumen. Therefore it is important to understand mechanism controlling VFA production and to depict VFA production in a model. This will allow us to devise strategies to enhance energy utilization and reduce methane production in ruminant livestock. An evaluation of a mechanistic model in predicting VFA production was conducted and equations were introduced into the model to improve the predictions. Later a continuous culture experiment was conducted to test the hypothesis on which those equations were based on. A mechanistic model -" Molly, was evaluated using a dataset with reported VFA production rates. The results of residual error analysis indicated that the root mean square prediction errors (RMSPE) were 63, 63, and 49% for acetate, propionate and butyrate, respectively. An assessment from two studies reporting VFA production revealed a potential of reducing errors of prediction by representing interconversion among VFA. In the second study, equations based on thermodynamics influence of pH and VFA concentration were introduced in the model to represent interconversion among VFA. The parameters for de novo VFA production and VFA absorption were re derived with (VFAInt) and without (BASE) the new interconversion equations. There were some improvements in the VFA concentration predictions but the improvements were both in VFAInt and BASE models. The RMSPE of VFA production were still above 50% for acetate, propionate and butyrate. The larger errors of predictions were attributed to measurement variation in VFA production literature, or possible incorrect rate constants for interconversion equations. Finally, a third study was conducted to assess the effect of pH, and VFA concentration on VFA and methane production in continuous culture. The treatments consisted of control, 20 mmol/d acetate infusion (INFAC), 7 mmol/d propionate infusion (INFPR), and low pH (LOWPH). Individual isotopes of acetate, propionate and butyrate were infused in the fermenters to estimate interconversions among VFA. With LOWPH treatment methane emission was reduced whereas production of propionate was increased. Hydrogen production was higher in INFAC indicating that some of the acetate could have been degraded to CO2 and H2. It was estimated that around 3 % of de novo acetate was converted to propionate and 9 % to butyrate. Exchange between propionate and butyrate was insignificant and below 1% of de novo production of either VFA. However, treatments did not affect interconversion rates among VFA. These results indicated that pH and VFA concentration do not have thermodynamic influence on VFA interconversion as hypothesized. Ph. D.

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Caunt, P. "Degradation of volatile fatty acids by immobilised bacteria." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233711.

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The aims of this project were to study the immobilisation of microorganisms and the use of immobilised cell preparations in biochemical reactors. One particular process, the biodegradation of volatile fatty acids (VFAs), was chosen as a model system. Volatile fatty acids are compounds which are commonly found in odorous wastes and so can present a pollution problem. A bacterium was isolated, which was capable of VFA degradation in a minimal medium. The organism was identified as a strain of Alcaligenes denitrificans. The strain was able to grow on, and degrade, individual straight chain VFAs and mixtures, at concentrations much higher than those used in the isolation conditions. The strain was found to grow at a wide range of pH values, and a moderately wide range of growth temperatures. The strain was also tested for the degradation of VFAs in piggery slurry, but was found to be less effective than the natural population of organisms present in the waste. This bacterium was used to assess various immobilisation techniques, and their suitability for use in bioreactors. Four gel entrapment systems were tested. Conventional polyacrylamide and aluminium alginate gels both resulted in loss of cell viability. Calcium alginate was found to be too fragile for use in bioreactors, and only polyacrylamide hydrazide gel was found to be suitable. Beads of polyacrylamide hydrazide were used for longer term operation in a bubble column reactor, in a series of experiments to study the effects of changes in operating conditions, on bioreactor efficiency. Mathematical correlations were developed to explain the effects. Other parameters such as the mass transfer coefficients were calculated, to assist in the prediction of scale up. The second immobilisation system tested was adsorption to inorganic matrices. Four different types of particle were tested for their ability to adsorb non-growing cells from solution. The capacity to adsorb cells was related to the surface properties of the particles. Celite diatomaceous earth particles were found to have the greatest capacity to adsorb cells. Celite beads could be seeded in this manner, and then operated in a bubble column bioreactor. A biofilm was formed on the beads, which was capable of steady state biodegradation when the reactor was operated at dilution rates above the theoretical maximum for free cell growth. Bubble columns were the most suitable reactor of those tested for use with immobilised cell preparations. Mixing in these reactors was sufficient to provide good mass transfer, but not so violent as to disrupt the immobilised cell particles. Cell immobilisation by adsorption onto Celite was found to have several advantages over the other systems tested. The matrix could adsorb large quantities of cells, resulting in rapid biofilm formation and was also relatively cheap. Therefore, this appears to be an excellent new technique, and its potential applications in industrial processes are discussed.

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Ganesan, Balasubramanian. "Catabolism of Amino acids to Volatile Fatty Acids by Lactococcus lactis." DigitalCommons@USU, 2005. https://digitalcommons.usu.edu/etd/5509.

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Lactic acid bacteria are essential as flavor producers of cheese and fermented products. They are capable of catabolizing aromatic, branched chain, and sulfur amino acids to flavor compounds. During cheese ripening the numbers of lactococcal colonies decrease, but lactococci survive without replication in culture. This prompted an investigation into possible mechanisms of catabolism of branched chain amino acids into branched chain fatty acids and the physiological relevance of amino acid catabolism to the bacteria. We hypothesized that lactococci catabolize branched chain amino acids to branched chain fatty acids during nonculturability. Lactococci, lactobacilli, and brevibacteria catabolized both branched chain amino acids and keto acids into branched chain fatty acids. Lactococci survived carbohydrate-limited conditions for over 4 yrs. Their survival was represented by maintaining intracellular ATP, enzyme activity, membrane integrity, capability of ATP- and PMF-dependent substrate transport, transcription, and catabolism of amino acids to fatty acids. Assays conducted with NMR spectroscopy coupled with in silico analysis showed that branched chain substrates are catabolized via keto acids, HMG-CoA, and acetyl-CoA to branched chain fatty acids. A short list of candidate genes was identified for the pathway by gene expression analysis coupled to NMR analysis. The expression of these genes and the presence of the related catabolites were identified in long-term starved cultures of nonculturable lactococci. This verified that catabolism of branched chain amino acids to branched chain fatty acids occurred during the nonculturable state only and in conditions of carbohydrate deprivation. The pathway also facilitated fixation of carbon by lactococci, revealing the mechanism of survival of lactococci over 4 yrs in culture without the addition of external carbon sources. Between strains the availability of carbohydrate and acid stress played significant roles in modulating their ability to produce branched chain catabolites. The ability of lactococci to catabolize branched chain amino acids during sugar starvation represents a shift in carbon catabolic routes. The identified pathway also represented a balance between catabolism and anabolism, suggesting that the bacteria were in a homeostatic state during nonculturability. We accepted the hypothesis that nonculturable lactococci catabolized branched chain amino acids to branched chain fatty acids during starvation./p>

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Long, Jennifer Erin. "Optimization of volatile fatty acids production in full-scale fermenters." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0018/MQ48064.pdf.

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Passanha, Pearl. "Improved polyhydroxyalkanoate production from selected volatile fatty acids using Cupriavidus necator." Thesis, University of South Wales, 2014. https://pure.southwales.ac.uk/en/studentthesis/improved-polyhydroxyalkanoate-production-from-selected-volatile-fatty-acids-using-cupriavidus-necator(18bc71e1-1514-4c4c-afe7-8d53ff23b0a1).html.

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This study aimed to develop methods to improve PHA production from selected volatile fatty acids (VFAs) and to improve the understanding of the PHA production process by pure culture bacterial fermentation using Cupriavidus necator. Optimisation strategies involved the following investigations using shake flasks and 5 litre based batch fermentations: Shake flask investigations determined that the temperature of 30oC and a nutrient medium, resulted in the highest growth of bacteria. A feeding strategy of the substrate (VFAs - acetic acid and butyric acid) was developed to avoid inhibition by the substrate and the alkaline buffer. The results established that continuous feeding of VFAs based on maintaining optimum pH around 7 resulted in enhanced PHA yields by almost 2-fold when compared to single pulse feeding of acetic and butyric acids (at 1, 2, 3, 4 and 5 g/l VFA concentration). A novel application of a capacitance probe was demonstrated to be able to monitor maximum PHA accumulation in-situ and in real-time, so as to prevent product and substrate loss (acetic and butyric acids, by a maximum value of 12 g/l and 20 g/l respectively), and to increase PHA process understanding and fermentation kinetics. The dielectric spectroscopy probe was able to correlate very well (R2 = 0.862) with PHA off-line measurements when operated in dual frequency mode and was able to establish the optimum PHA harvesting time, which would have resulted in improved process economics and environmental performance. Shake flask experiments were conducted to investigate the addition of trace metals (zinc, manganese, boric acid, cobalt, nickel and sodium molybdate), copper and sodium chloride in nutrient media and its effects on bacteria growth. NaCl contributed to the greatest enhancement in the early growth of bacteria and therefore fed batch fermentations using 0, 3.5, 6.5, 9, 12 and 15 g/l of additional NaCl concentrations were evaluated. The 9 g/l NaCl concentration showed the highest PHA production of 5.33 g/l and also caused PHA accumulation to occur earlier by 2 h than the control. The capacitance probe also helped visualise and understand the bacterial growth and PHA accumulation profile. The novel use of low cost digestates based media was demonstrated. Results demonstrated that possibly due to the nutrients/trace elements in a digestate (from food wastes and wheat feed) the PHA accumulation was enhanced by 3-fold (to 12.29 g/l); with a resulting highest ever reported PHA accumulation of 90% for C. necator. C: N: K: P: S ratios for this digestate based fermentation were found to be for growth 761: 31: 1: 3.5: 1.9 and for PHA accumulation 1132: 11: 3: 1.7: 1. Digestates use within biotechnology and biorefining specifically for bacterial applications could provide another alternative route to digestate disposal that may lead to valuable end products. All the above evaluations represented novelty and have delivered significant process optimisation for PHA production from VFAs.

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McPeak, David W. (David William). "The behavior of volatile fatty acids in model solutions during freeze-drying /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65359.

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Teiseh, Eliasu Azinyui. "Anaerobic hydrogen production by photosynthetic purplenonsulfur [sic] bacteria using volatile fatty acids." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594490411&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Chakraborty, Sagar Ph D. Massachusetts Institute of Technology. "Exploring volatile fatty acids (VFAs) as a novel substrate for microbial oil production." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98701.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015. Cataloged from PDF version of thesis. Includes bibliographical references. Cost effective production of biofuels depends critically on feedstock cost and availability. As such, volatile fatty acids (VFAs) can play an important role in advancing sustainable biofuel production since they can be derived from low cost feedstock including gases and municipal solid waste. To this end, we studied fermentations of the oleaginous microbe Yarrowia lipolytica engineered for lipid overproduction. With acetate as sole carbon source, we conducted fed batch fermentations of Y. lipolytica in which acetic acid was maintained at low, non-inhibitory levels yielding high lipid titer of 50 g/L and productivity of 0.25 g/L/h, along with a lipid content of 60%. We also conducted fed batch fermentations with cell recycle to utilize dilute steams of acetic acid that essentially replicated the results of the fed batch process. Carbon balances were satisfied and no excess carbon dioxide production was detected beyond the amounts associated with biomass formation and product synthesis. Acetate is one member of the entire range of VFAs produced from municipal solid waste (MSW) via anaerobic digestion; thus, facilitating the use of MSW as a primary feedstock would be contingent on the ability of the above strain to grow on a mixture of VFAs. Given the insufficient literature examining microbial growth on VFAs, one of the goals of this project was to explore individual as well as mixed VFAs as a feedstock for Y.lipolytica. Dilute stream of mixed VFAs were successfully used as feed in bioreactor studies to obtain high cell density cultures. Similar results with respect to lipid production were obtained in comparison to the study on acetate. In addition, the microbe could tolerate perturbations in the feed composition and grow to similar cell densities. The success in establishing VFAs as a potential substrate for lipid accumulation in Yarrowia lipolytica raises the possibility of a two-stage commercial bioprocess enabling biodiesel production from MSW. by Sagar Chakraborty. Ph. D.

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Abegg, Richard. "Volatile fatty acids in digesta samples of cows with spontaneous cecal dilatation/dislocation /." [S.l.] : [s.n.], 1998. http://www.stub.unibe.ch/html/haupt/datenbanken/diss/bestell.html.

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McDougall, Forbes Russell. "Optimization and evaluation of the acidification stage of a two-phase anaerobic digester treating coffee wastewater." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318254.

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Copelin, Jacob E. "Effects of supplemental 2-hydroxy-(4-methylthio) butanoic acid and branched chain volatile fatty acids in lactating dairy cows." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu157487131308709.

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Atiq, Omar. "Feasibility of membrane processes for Volatile Fatty Acids (VFAs) concentration:data elaboration, modelling and design." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

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The need for recovery and concentrate a Volatile Fatty Acids (VFAs) effluent resulting from a biological fermentation step, has aimed a feasibility study on pressure-driven membrane separation processing. A previous experimental campaign, carried out at LABIC-DICAM for the NoAW (No-Agricultural Waste) EU project, involving total recirculation and concentration trials on RO and NF modules, was the starting point for subsequent elaboration, modelling, simulation and preliminary design. The presented mass transfer-solution modelling allowed the estimation of both VFAs and Na+ real rejections for all investigated total recirculation trials. The modelling ability to assess the system’s osmotic pressure and polarization magnitude was successfully tested accounting for the validity of the osmotic-pressure model. Total recirculation trials calculated real rejections trends were interpolated using the Mason&Lonsdale and solution-diffusion transport models, providing a set of adjustable parameters. The interpolated RReal (Jv) curves were used in the simulation of the experimental concentration trials, proving our capability to fairly faithfully reproduce the experimental trends. The accomplishment encouraged the simulation of further concentration trials whose experimental evidence was not available. The simulations aimed at investigating the modules performances for different applied pressures with the final objective of identifying a few design best cases. Two possible process alternatives were proposed: pure RO process and an integrated process RO + NF. Subsequent comparison of the alternatives’ preliminary design best-cases showed the two to be competitive.

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Malcom, Annie, Kaitlyn Webb, and W. Andrew Clark. "Profile of Volatile Fatty Acids in The Feces Of Normal And Overweight College Students." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/2512.

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Sydney, Eduardo Bittencourt. "Valorization of vinasse as broth for biological hydrogen and volatile fatty acids production by means of anaerobic bacteria." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2013. http://tel.archives-ouvertes.fr/tel-00914329.

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Vinasse is the liquid waste removed from the base of sugarcane ethanol distillation columns at a ratio of 12-15 liters per liter of alcohol, resulting in an estimated production of approx. 350 billion liters in 2012/2013 in Brazil. Vinasse has a low pH and high chemical oxygen demand, which can cause land desertification when indiscriminately used as fertilizer. Also, underground water contamination is being observed in some regions. We evaluated the potential of vinasse as nutrient source for biohydrogen and volatile fatty acids production by means of anaerobic consortia. Two different vinasse-based media were proposed, using sugarcane juice or molasses as carbon source, and were compared to fermentation in a sucrosesupplemented medium. Pure cultures (4) and consortia (7) were cultured in the propose media and evaluated for volatile fatty acids (VFAs) and biohydrogen production. The consortium LPBAH1, originated from faeces of fruit bat, was selected for fermentation of vinasse supplemented with sugarcane juice and resulted in a higher H2 yield of 7.14 molH2/molsucrose and hydrogen content in biogas of approx. 31% after process optimization. Similarly, the optimized process using the consortium LPBAH2, originated from a lake of a dairy farm, resulted in 3.66 molH2/molsucrose and 32.7% hydrogen content in biogas. The proposed process is of great importance for giving a more rational destination to vinasse and expanding Brazilian energy matrix, reducing the dependence of fossil fuels.

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Turkmenoglu, Secil. "Organic Acids Production From Cheese-whey." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607709/index.pdf.

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In this study, production of organic acids from cheese-whey was studied. Optimization of organic acids production was performed in semi-batch and batch reactors. Two sets of experiments were performed. First set of experiments were performed in semi-batch reactors for the optimization of organic loading rate (OLR) and hydraulic retention time (HRT). As a result of Set 1 experiments optimum OLR was found to be 15 g COD l-1. Second set of experiments were performed in batch reactors by using the optimum OLR found in Set 1 experiments. Set 2 experiments were conducted to study the effect of using different seed cultures and Basal Media (BM) on Volatile fatty avid (VFA) production. Main acidogenesis products were acetic acid (Hac), butyric acid (Buty) and propionic acid (HPr) with smaller quantities of i-butyric acid (i-Buty), valeric acid (Val) and caproic acid (Cap). It was seen that BM had a suppressive effect on ethanol (EtOH) production while it stimulated the VFA production. Higher VFA productions and variety of VFA types were observed in Test Reactors seeded with acidogenic culture (R3 and R6).

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He, Xuan (Sarah). "The use of naturally generated volatile fatty acids for pesticide removal during the denitrification process." Thesis, University of Canterbury. Civil Engineering, 2006. http://hdl.handle.net/10092/1169.

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The effect of naturally produced volatile fatty acids (VFAs) on the removal of 2, 4-D from a wastewater during the denitrification process was studied in this thesis. The VFAs were generated from an anaerobic digester using soya flour solution as a synthetic feed. The digester was operated at an SRT and HRT of 10 days. The pH (4.8 ± 0.2) and temperature (32 ± 3 ℃) of the digester were not controlled. A mean VFA concentration of 3153 ± 801 mg/L was achieved with acid speciation results of acetic (51.4 %), propionic (27.5 %), n-butyric (19.6 %) and iso-valeric (1.4 %). The specific VFA production rate was 0.014 mg VFA/mg VSS/day. The extent of the digestion process converting the substrate from a particulate to soluble form was evaluated as the specific TOC solubilization rate (0.007 mg TOC/mg VSS/day), soluble COD production rate (0.022 mg SCOD/mg VSS/day) and percent VSS reduction (14 %). The low solubilization rate is possibly due to high feed solids (3.4%) which led to a heavily overloaded bioreactor. It also suggests that the particulate substrate was not entirely amenable to solubilization. The acclimation of 2, 4-D degrading bacteria was developed successfully in an SBR fed with sewage and 2, 4-D (30-100 mg/L) as carbon and energy sources. A mean MLSS of 3653 ± 547 mg/L and an SRT of 20 ± 9 days were observed during the research period. The settleability of the SBR sludge was excellent evidenced by a low sludge volume index (SVI) of 101 ± 50 mL/g and less than 5 mg/L of effluent suspended solids. The specific 2, 4-D degradation rate was 0.046 ± 0.018 mg/mg MLSS/day. However, the removal of 2, 4-D during 60 minutes of non-aerated phase was negligible while more than 90 % of the 2, 4-D was removed within 240 minutes of the aerated phase. The successful degradation of 2, 4-D is related to the length of the acclimation period, as the acclimation period increased, the specific biodegradation rate increased. A biosorption study using ultrasound pre-treatment of the SBR acclimated biomass suggested that less than 10 % of the removal of 2, 4-D was due to biosorption, while more than 90 % removal of the 2, 4-D was likely due to biodegradation. Denitrification batch tests (using SBR-acclimated biomass) demonstrated that the addition of a digester effluent rich in naturally-produced VFAs increased both the 2 specific denitrification rate and the 2, 4-D degradation efficiency, as compared to that using 2, 4-D as a sole carbon source. In particular, the specific denitrification rates increased from 0.0119 ± 0.0039 to 0.0192 ± 0.0079 to 0.024 ± 0.003 g NO₃-N/g VSS per day, when using 2, 4-D alone, 2, 4-D plus natural VFAs and natural VFAs alone as carbon sources. The percent 2, 4-D removal increased from 28.33 ± 11.88 using 2, 4-D alone as a carbon source to 54.17 ± 21.89 using 2, 4-D plus natural VFAs as carbon sources. The specific 2, 4-D degradation rate and 2, 4-D removal efficiency of unacclimated biomass were 2.0 to 2.5 times less than those of the acclimated biomass. Natural VFAs and synthetic VFAs were found to be identical in denitrification batch tests in terms of their use as a carbon source. The mean specific denitrification and VFA-C consumption rates as well as the mean specific 2, 4-D degradation rate derived from experiments using natural VFAs and 2, 4-D as carbon sources were close to the valuess from experiments using synthetic VFAs and 2, 4-D as carbon sources. Further exploration of 2, 4-D degradation behaviour with pulsed additions of NO₃-N did not find further significant 2, 4-D removal, although almost all of NO₃-N was used by the end of the experimental run due to endogenous carbon sources used for cell maintenance and growth. However, the higher the concentration of biomass used in the denitrification batch system, the larger the amount of 2, 4-D degraded and the faster the VFA-C and NO₃-N were consumed. Further research with respect to optimisation of the acid-phase anaerobic digestion process (e.g. to adjust SRT and HRT or to lower the solid content of synthetic feed) would improve the specific VFA production rate and the solubilization rate. More research on the SBR could be carried out to investigate its maximum 2, 4-D removal capability as well as the removal of other structurally related herbicides. Attempts could be made to stimulate the growth of denitrifiers in the SBR (e.g. to add certain amounts of NO₃-N according to proper C: N ratios or to increase the length of non-aerated time). More microbiological studies of 2, 4-D degrading bacteria may also be helpful to understand the combined SBR/denitrification and 2, 4-D degradation process. More theoretical aspects of modelling kinetics could be developed to apply the combined process in-situ at 2, 4-D contaminated sites.

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Smith, Darron Louis. "The effect and mechanism of action of volatile fatty acids on the catabolism of progesterone." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4243.

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Thesis (Ph. D.)--West Virginia University, 2005. Title from document title page. Document formatted into pages; contains x, 88 p. : ill. Vita. Includes abstract. Includes bibliographical references.

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Roman-Garcia, Yairanex. "Assessing Dietary Conditions Influencing the Requirements by Rumen Bacteria for Branched Chain Volatile Fatty Acids." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1557171743925883.

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Alshwan, Zahraa, and Simon Hultman. "Production of volatile fatty acids from anaerobic digestion using food waste, sludge and cow manure." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-21642.

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Volatile fatty acids (VFAs) are important building blocks for the chemical industry. These acids can be produced through environmentally friendly processes from a variety of wastes, such as food waste, sludge and cow manure, through anaerobic digestion (AD). The main objective of this thesis was to investigate which operating parameters (e.g. pH, retention time, mix of substrate etc.) are optimal for producing VFAs as efficiently as possible, through AD batch processes. The highest VFA concentration was reached at pH 10 and at day 11 when food waste and sludge were used as substrate to a value of 15.4 g/L, corresponding to 0.77 g VFAs/ g of VSfed. Highest VFA concentration where cow manure was used as substrate was reached on day 10 and with a value of about 10 g/L corresponding to 0.51 g VFAs/ g VSfed. Flyktiga fettsyror (VFAs) är en viktig byggsten inom den globala kemiindustrin. Dessa fettsyror kan produceras med hjälp av miljövänliga processer där en mängd olika sorters avfall, som t.ex. matavfall, avloppsslam och koavföring kan fungera som substrat, genom anaerobisk rötning. Det huvudsakliga målet med den här kandidatuppsatsen var att utreda vilka de optimala driftförhållanden var för särskilt utvalda driftparametrar (t.ex. pH, retentionstid, mix av substrat etc.) för att producera flyktiga fettsyror så effektivt som möjligt, genom anaerobisk rötning. Högst koncentration av VFAs nåddes vid pH 10 på dag 11 när matavfall och avloppsslam användes tillsammans som substrat till ett värde på 15 g/L, vilket motsvarar en avkastning på 0.77 g VFAs / g VSin. Högst VFAs-koncentration när koavföring användes som substrat nåddes på dag 10 med ett värde på 10 g/L, motsvarande en avkastning på 0.51 g VFA/ g VSin.

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Liu, Hung-Jyh. "Volatile fatty acid and formic acid metabolism in sheep : a thesis submitted to the University of Adelaide in fulfilment of the requirements for the degree of Master of Agricultural Science." Title page, contents and summary only, 1990. http://web4.library.adelaide.edu.au/theses/09A/09al783.pdf.

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Includes bibliographical references (leaves 59-79) Examines the metabolism of volatile fatty acid and formic acid in fed sheep. Develops a method for analysing and qualifying volatile fatty acids with special reference to formic acid in biological fluids by High-Performance Liquid Chromatography.

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Gupta, Ashok Kumar. "The effects of temperature, pH and retention time on volatile fatty acids production from primary sludge." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26292.

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A typical biological phosphorus removal process consists of alternate anaerobic and aerobic zones. Recent research at the University of British Columbia (UBC) has indicated that the addition of volatile fatty acids (VFA's) to the anaerobic zone of Bio-P processes improves the overall phosphorus removal efficiency, at least when treating weak sewage. At the full-scale biological phosphorus removal plant at Kelowna, B.C., and at a pilot-scale facility at UBC, anaerobic fermentation of primary sludge has been used to produce VFA's to add to the anaerobic zone of these processes. The primary objective of this research was to improve the knowledge of the acid phase of anaerobic digestion (the production of VFA's) to help achieve optimum design and operation of the fermenter. The effects of temperature, retention time and pH on the production of short-chain VFA's from primary sewage sludge were studied at lab-scale. Oxidation reduction potential (ORP) was also monitored throughout the study to explore the relationship between ORP and the production of VFA's. A completely random 3X3X2 factorial experimental design was used to determine the experimental sequence. Three litre anaerobic reactors were run on a fill and draw basis in a temperature-controlled room. Reactors were fed once a day with primary sludge brought from the UBC pilot plant. Results showed that the net VFA production consistently improved with increase in temperature in the range of 10°C to 30°C. At low temperatures (10°C and 20°C) the net VFA production improved with the increase in retention time; however extension of the retention time to 9 days at 30°C appeared detrimental to VFA production. The effect of pH control, at a value of 7.0, was not consistent with both retention time and temperature and had a confounding effect. At 10°C and 20°C temperatures, a relationship was observed between ORP and VFA production. No definite relationship between the net VFA production and ORP was found at 30°C. Applied Science, Faculty of Civil Engineering, Department of Graduate

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Chail, Arkopriya. "Effects of Beef Finishing Diets and Muscle Type on Meat Quality, Fatty Acids and Volatile Compounds." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4479.

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Consumer evaluation, proximate data, Warner-Bratzler shear force (WBSF), fatty acid (FA) composition and volatile compounds were analyzed from the Longissimus thoracis (LT), Tricep brachii (TB) and Gluteus medius (GM) muscles finished on conventional feedlot (FL) and forages, including a perennial legume, birdsfoot trefoil (BFT; Lotus corniculatus), and a grass, meadow brome (Bromus riparius Rehmann, Grass). Representative retail forage (USDA Certified Organic Grass-fed, COGF) and conventional beef (USDA Top Choice, TC) were investigated (n = 6) for LT. Additionally, the effects of diet on Gluteus medius (GM) and Tricep brachii (TB) muscles were explored. Forage-finished beef scored lower (P < 0.05) in most of the affected sensory attributes except BFT which was similar to grain-finished beef. In forage-finished beef GM was more liked and in FL, TB was similar to GM except juiciness where it scored greater. The fat percent was found to be greatest (P < 0.05) in TC followed by BFT and FL. Nutritionally beneficial ratios of FAs were observed in forage-finished diet. Fatty acid concentrations were majorly affected (P ≤ 0.046) by diet. Few long-chain PUFAs were affected (P ≤ 0.015) by muscle type. No FA was a effected (P > 0.05) by the interaction of muscle and diet. 3-hydroxy-2-butanone, known to evoke a buttery sensation was affected (P = 0.011) by diet with greater (P < 0.05) concentration in GM across all diets. Strecker degradation products were affected (P ≤ 0.014) by muscle type being prominent in GM. Meanwhile, 2-ethyl-3,5-dimethyl-pyrazine was greatest (P < 0.05) in BFT. All pyrazine compounds were (P < 0.05) greater in GM. These results indicate that when consumer evaluated beef of finishing diets, FL beef was rated highly. Additionally, not all forages produce similar beef. There were similar ratings for BFT for all attributes except flavor having lower values compared with FL. The chemical composition of BFT beef was found to be intermediary and similar to both FL and Grass beef in many cases. Diet was found to interact with muscle for sensory and chemical measures. The GM and TB of FL did not differ (P < 0.05), while within forage treatments sensory response and chemical composition varied. These results indicate the meat quality of secondary beef muscles is more greatly impacted by forage diets.

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Pan, Chengyang. "Application of volatile fatty acids from waste as an external carbon source for the denitrification process." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264538.

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The gap between resource demand for the industrialized world and non-renewable feedstock like fossil fuels, essential agricultural fertilizer is getting increasingly severe, which has resulted in alarming-increasingly impacts on worldwide environmental problems. Meanwhile, wastewater treatment plants (WWTPs), as an essential facility for urbanization, is also confronting new rising challenges such as energy consumption and operation costs rather than only improving effluent wastewater quality. It is thereby important to develop new approaches for next-generation WWTPs with less energy consumption and costs in a sustainable way. The objective was to study the application of volatile fatty acids (VFAs) from waste as an external carbon source on denitrification by manometric tracking method in the lab-scale. Food waste and primary sludge were used for anaerobic fermentation to produce VFAs, which was then used as a sole external carbon source with various C/N ratio in denitrification batch test. The results were compared with traditional external carbon sources, acetate and methanol. It was found that the maximum denitrification rate with VFAs as an external carbon source was 15.73 ± 0.95 mg NOx-N/g VSS h, faster than those with acetate and methanol as external carbon sources. When C/N ratio ≥ 4.5 nitrate removal efficiency and the highest maximum denitrification rate were reached, the optimum C/N ratio for dosing VFAs as an external carbon source was thus determined as 4.5. In addition, denitrification capacity experiments with addition of VFAs produced from three different pH-controlled digestion reactors as an external carbon source were then conducted under an optimum C/N ratio of 4.5. As a result of the composition difference between VFAs produced from different pH environment, it was observed that, with VFAs from pH-10 digestion reactor denitrification rate was slightly higher than those with VFAs from pH-5 and none-pH-controlled digestion reactors. Furthermore, denitrification batch test using chemical tracking method was conducted to compare with manometric tracking method, and it was proven that the results obtained from manometric denitrification tests were reliable and valid. The overall results show that VFAs produced from anaerobic fermentation are an excellent external carbon source for denitrification, and it realizes the utilization of carbon resource recovery from WWTPs, which is crucial for next-generation wastewater treatment. Klyftan mellan resursefterfrågan i den industrialiserade världen och icke-förnybar råvara som fossila bränslen, essentiell jordbruksgödsel, blir allt svårare, vilket har resulterat i oroväckande effekter på globala miljöproblem. Samtidigt står avloppsreningsverk (ARV), som är en viktig anläggning för urbanisering, inför nya ökande utmaningar som energiförbrukning och driftkostnader snarare än att förbättra kvaliteten på renat avloppsvatten. Det är därmed viktigt att utveckla nya strategier för nästa generations ARV med mindre energiförbrukning och kostnader på ett hållbart sätt. Målet var att studera tillämpningen av flyktiga fettsyror (VFA) från avfall som en extern kolkälla i denitrifikation med manometrisk metod i laboratorieskala. Matavfall och primärslam användes för anaerob rötning för att producera VFA, som sedan användes som en extern kolkälla med olika C/N-förhållanden i denitrifikationstest. Resultaten jämfördes med traditionella externa kolkällor, acetat och metanol. Det visade sig att maximal denitrifikationskapacitet med VFA som extern kolkälla var 15,73 ± 0,95 mg NOx-N/g VSS h, snabbare än de med acetat och metanol som extern kolkälla. När C/N-förhållandet ≥4,5 uppnåddes högsta nitratborttagningseffektivitet och maximala denitrifikationskapacitet, varför det optimala C/N-förhållandet för dosering av VFA som extern kolkälla bestäms som 4,5. Dessutom genomfördes experiment med denitrifikationskapacitets med tillsats av VFA producerat från tre olika pH-kontrollerade rötningsreaktorer som externa kolkällor under ett optimalt C/N-förhållande av 4,5. Som ett resultat av kompositionsskillnaden mellan VFA producerade från olika pH-miljöer, det observerades att med VFA från pH-10 kontrollerad reaktor denitrifikationskapacitet var något högre än med VFA från pH-5 och en icke-pH-kontrollerad reaktor. Vidare utfördes denitrifikationstest med användning av kemisk metod för jämförelse med manometrisk metod, och det visades att resultat erhållna från manometrisk denitrifikationstest var tillförlitliga och giltiga. De övergripande resultaten visar att VFA som produceras från anaerob rötning är en utmärkt extern kolkälla för denitrifikationsprocessen, vilket betyder att utnyttjandet av kolresursåtervinning från AVR är avgörande för nästa generations avloppsrening.

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Restrepo, P. Ricardo J. "Dry matter digestibility and VFA production of selected feedstuffs using RUSITEC /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9901273.

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Bendada, Domingos Joana Margarida <1988&gt. "Development of Biorefinery Schemes for the Production and Recovery of Volatile Fatty Acids from Agro-Industrial Wastes." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/8035/11/BendadaDomingos_JoanaMargarida_tesi.pdf.

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Volatile fatty acid (VFAs) represent the final product of anaerobic acidogenic fermentation and can be exploited as precursors for the production of added-value chemicals. The biotechnological conversion of agro-industrial wastes into VFAs can be considered a valuable alternative to waste disposal. However, the productivity of processes, which refer to the carboxylation platform are affected by the purity of produced VFAs. Biosphere SRL (Forli, Italy) had started to valorize wastes to obtain biogas. VFAs were produced using maize silage (MS), vegetable waste (VW) and cheese whey (CW) as feedstock. The co-digestion of VW (70%) MS (30%) (VMW) under continuous operation with hydraulic retention time (HRT) of 6 days and a controlled pH 7 resulted in a VFAs rich solution of 30 g.L-1. The fermentation of CW was performed in a packed bed bioreactor where Vukuopor was the supported material. The HRT, organic loading rate (OLR) and pH were parameters tested under continuous operation. By a HRT of 6 days, ORL of 4.2 g.L-1.d-1, and pH 5.8−6, 16 g·L-1 of total VFAs were produced, with a yield higher than 75%. Electrodialysis (ED) process was studied for the concentration of VFAs from the two acidogenic effluents resulted from the previous mentioned anaerobic acidogenic digestions. Under potentiostat operation the VMW concentration stream was concentrated from 29 g.L-1 to 50 g.L-1. Thought it is expected that a concentration of 100 g.L-1 can be achieved by performing sequential batch. With CW acidified effluent the concentration achieved was similar however the initial solution was poor in VFAs. Experiments with Nanofiltration were performed for the separation of ferulic acid (FA) and sugars from an enzymatic hydrolysate of wheat bran. Eight different membranes were screened at different pressures and solution pH. The best condition was found be membrane NT7450 operated at pH 9 and 16 bar.

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Pessiot, Jérémy. "Développement d'une unité pilote de bioraffinerie permettant la mixogenèse en continu à partir de la biomasse non alimentaire via la fermentation anaérobie mésophile." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22524.

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Les réserves de pétrole sont sur le déclin, les prix des ressources fossiles fluctuent et le CO 2 dégagé par leur consommation contribue inéluctablement au réchauffement climatique. Ce phénomène, conduit notre société vers l'utilisation accrue de biomasse pour la génération d'énergie, de composés chimiques et de matériaux. La réduction des déchets est considérée comme indissociable de cette transition énergétique et en opposition aux préjugés, l’accroissement des déchets organiques peut être bénéfique dans cette recherche de solutions alternatives. En effet, cela conduit à la génération de grandes quantités de matières qui peuvent représenter de potentielles ressources. De plus, changer le statut des déchets en coproduits pour la production de bioénergies n’entre pas en concurrence avec les filières alimentaires et cela constitue un des principaux enjeux des biotechnologies. Sous certaines conditions, les bioconversions anaérobies représentent des procédés d’ingénierie prometteurs pour accomplir le double enjeu de la valorisation des coproduits et de la production de molécules d’intérêt énergétique et chimique (biocarburants, chimie verte...). En revanche, l’innovation dans les biotechnologies blanches est nécessaire pour la production robuste, performante, rentable et environnementalement acceptable de biomolécules à partir de ressources renouvelables. Dans ce contexte, la société AFYREN a été pensée et créée pour répondre à ce défi mondial via sa technologie « tout en un », AFYNERIE, qui s’inspire de la nature et des sciences. L’objectif premier de ce travail de thèse, cœur du procédé AFYNERIE, était d’étudier les performances de microorganismes anaérobies, sous forme de souches pures ou de consortia pour la valorisation de substrats plus ou moins complexes via un processus de méthanogenèse avortée. Pour cela, il était nécessaire de considérer, déjà à l’échelle du laboratoire, une projection dans le monde industriel. Nous avons alors démontré les capacités de la diversité microbienne à produire des molécules plateformes à partir de coproduits agro-industriels réels en mode stérile puis non stérile. Cette étude s’est appuyée en parallèle sur la caractérisation et la dynamique des populations microbiennes mises en jeu. Ensuite, l’accumulation des métabolites, à la fois inhibiteurs et d’intérêt, dans les milieux fermentaires en mode discontinu et avec des rendements compétitifs, a débouché sur la nécessité de surpasser ces limitations par le passage à un mode continu. Pour ce faire, un procédé d’extraction biocompatible des synthons issus de l’opération de fermentation a été mise en œuvre selon différents mode de réalisations. Ce couplage des opérations unitaires, sous forme de fermentation extractive, a livré des résultats prometteurs tout en étant bâtit dans un cadre de bioraffinerie et d’écologie industrielle qui tend vers le « zéro déchet ». Enfin, à l’inverse des autres technologies émergentes, pour se placer dans une approche de drop-in, la biologie et la chimie ont été associées. Le but a été d’illustrer la multipotence des acides gras volatils (AGVs) en termes d’applications industrielles et de réaliser la preuve de concept de la transformation de la biomasse non alimentaire en biomolécules d’intérêt énergétique et chimique. Ces travaux ont permis de soulever les points clés du changement d’échelle du procédé AFYNERIE et d’entrevoir des perspectives tant fondamentales qu’appliquées. Cette brique technologique, de par sa philosophie multi-intrants/multi-produits, couplant fermentation-extraction-synthèse, permet d’initier la transition au stade pilote d’un procédé innovant compatible avec une future économie biosourcée Fossil oil reserves are decreasing, oil prices are fluctuating, and the CO 2 released by oil consumption contributes to global warming. These are driving our society towards increased use of biomass for energy, chemical compounds and other materials. Minimizing waste has been seen as a concern associated with alternative energy efforts. Contrary to expectation, increasing organic waste can be beneficial for alternative energy efforts, because it would result in large amounts of organic resources that can be potential raw materials. Moreover, using waste as a resource for bioenergy production does not compete with human or animal food or agricultural surfaces, and that is one of the greatest challenges facing biotechnology. Using waste as a resource for biomolecule production would thus be an interesting approach to reducing waste in the environment and producing renewable materials. Under specific conditions, detrital biomass can be converted into biomolecules of interest by microorganisms. Anaerobic fermentation techniques represent promising engineering processes for accomplishing the dual goals of waste reduction and renewable biomolecule production for biofuel and green chemistry markets. On the other hand, innovative fermentation processes are necessary for the strong, successful, cost-effective and eco-friendly production of bulk chemicals from renewable resources. In this context, AFYREN company was thought and founded to answer this world challenge through its “all in one” technology, AFYNERIE, which is inspired from the nature and sciences. The first objective of this thesis, heart of the AFYNERIE process, was to study the performances of anaerobic microorganisms, in the form of pure strains or of consortia for the valorization of more or less complex substrata via a process of failed methanogenesis. For that purpose, it was necessary to consider, already at the laboratory scale, a projection in the industrial world. Then, we demonstrated the capacities of the microbial diversity to produce platform molecules from real agro-industrial by-products in sterile and then non sterile mode. This study leaned in parallel on the characterization and the dynamics of involved microbial populations. Then, the accumulation of metabolites, which are at the same time inhibitory and of interest, in fermentative media in batch mode and with competitive yields, resulted in the necessity of surpassing these limitations by the passage in a continuous mode. To do this, a process consisted of a biocompatible extraction of synthons stemming from the operation of fermentation was implemented according to different mode of realizations. This coupling of single operations, in the form of extractive fermentation, delivered promising results while builds in a frame of biorefinery and industrial ecology which tightens towards a “zero waste”. Finally, contrary to the other emergent technologies, to take place in a drop-in approach, biology and chemistry were associated. The purpose was to illustrate the versatility of volatile fatty acids (VFAs) in terms of industrial applications and to realize the proof of concept of the transformation of the non-food biomass in biomolecules of energy and chemical interest. These works allowed to underline key points of the scale-up of AFYNERIE process and to glimpse perspectives fundamental as well as applied perspectives. This technological brick, due to its multi-inputs / multi-products philosophy, coupling fermentation-extraction-synthesis, allows to introduce the transition to the pilot stage of an innovative process compatible with a future biobased economy

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Bertrand, Martin. "Suivi de l'ATP et des protéines du biofilm dans un bioréacteur a lit fluidisé fermentant un perméat de lactosérum reconstitué /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2002. http://theses.uqac.ca.

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Beligon, Vanessa. "Valorisation d'acides gras volatils issus de fermentation anaérobie par la production de lipides microbiens, précurseurs de biodiesel." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22687/document.

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Une part importante de la production mondiale de vecteurs énergétiques et de produits chimiques provient de la raffinerie de combustibles fossiles. En raison de l'augmentation du prix du pétrole et de son impact environnemental, la recherche de solutions alternatives, écologiques et économiques constitue l’un des enjeux de notre siècle. Le remplacement du pétrole par de la biomasse en tant que matière première pour la production de carburants et de produits chimiques constitue la force motrice dans le développement de complexes de bioraffinerie.Cette étude fait partie d’un projet de bioraffinerie visant la valorisation de biomasse lignocellulosique par la production d’hydrogène et de lipides microbiens précurseurs de biodiesel. Ce travail se concentre en particulier sur l’étape de production de biomasse et de lipides par la levure oléagineuse Cryptococcus curvatus à partir d’acides gras volatils (AGVs) synthétisés au cours de la fermentation anaérobie productrice d’hydrogène. Les cultures ont dans un premier temps été réalisées à partir d’un substrat modèle, l’acétate, en fed-batch et en continu. La détermination de l’influence de différents paramètres opératoires sur la production de biomasse et de lipides à partir d’acétate a permis de mettre au point des cultures en fed-batch dont les cinétiques, les productivités et les rendements finaux étaient compétitifs avec ceux rapportés dans la littérature pour des cultures sur substrats simples. Un modèle de croissance et de production de lipides a été construit à partir de ces données afin de prédire le comportement de la souche lors de cultures continues, permettant d’obtenir des productivités en lipides et en biomasse élevées. Enfin, des cultures ont été menées à partir d’AGVs issus de surnageant de fermentation anaérobie. Les résultats ont confirmé la croissance de ces levures sur ce substrat particulier et la production de lipides dont la composition en acides gras estérifiés était compatible avec une utilisation comme biodiesel A great part of the global production of energy vectors and chemicals comes from fossil fuels refinery. Because of the increase in oil price and their environmental impacts, the search for alternative, ecological and economic solutions is a current challenge. The replacement of oil with biomass as raw material for the production of fuels and chemicals is the driving force for the development of biorefinery complexes.This study is part of a project aiming at the biorefinery of lignocellulosic biomass for hydrogen and microbial lipids as biodiesel precursors. This work focuses on the biomass and lipids production step by the oleaginous yeast Cryptococcus curvatus using volatile fatty acids (VFAs) as carbon sources, which are synthesized during the anaerobic fermentation step. Yeast cultures have initially been realized using a model substrate, acetate, and fed-batch and continuous modes. The determination of the influence of different operating parameters on the biomass and lipids production led to the development of fed-batch cultures which kinetics, productivities and yields were competitive with those reported in the literature for cultures on simple substrates. A growth and lipid production model was built from these data to predict the behavior of the strain during continuous cultures and to obtain high lipid and biomass productivities. Finally, cultures were conducted using VFAs from anaerobic fermentation supernatant. The results confirmed the growth of these yeasts on this particular substrate and the production of lipids which composition was compatible with use as biodiesel

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Beckett, Linda Marie. "Effects of ruminal nutrient degradability on volatile fatty acid dynamics, ruminal epithelial gene expression, and post-absorptive system." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/87471.

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This study evaluated degradable nutrient supply effects on VFA concentrations, fluid flux and pool sizes, rumen epithelial metabolic and absorptive genes, and post-absorptive muscle and blood responses. Six ruminally cannulated Holstein heifers (BW=330 ± 11.3 kg) were used in a partially replicated Latin Square experiment with four treatments consisting of beet pulp or timothy hay and barley or corn grain. Periods were18 d with 3 d diet adaptation and 15 d of treatment. During each period, d 10 to 14 was used for in situ nutrient degradation assessment, d 16 to 18 was used for rumen fluid sampling, and d 18 was used for rumen papillae and skeletal muscle biopsies and blood sampling. In situ ruminal starch disappearance rate (barley 7.61 to 10.5 %/h vs corn 7.30 to 8.72%/h; P = 0.05) and extent of fiber disappearance (timothy hay 22.2 to 33.4 % DM vs beet pulp 34.4 to 38.7 % DM P=0.0007) differed significantly among diets. Acetate (P = 0.02) and isovalerate (P = 0.008) molar percentages (% mol) were increased by timothy hay, but propionate (P = 0.06) and valerate (P = 0.10) molar percentages were decreased. Corn increased propionate (P = 0.02) and valerate (P = 0.049) molar percentage, but decreased butyrate (P = 0.04) molar proportion. Fluid volume and fluid passage rate, and individual VFA pool sizes were not influenced by diet (P > 0.05). Four epithelial genes, two metabolic and two absorptive, had increased expression on timothy hay diets (P < 0.15). Blood acetate concentration was influenced by treatment (P = 0.067) but no other blood metabolites were. Skeletal muscle metabolic rate was significantly increased on corn diets (P = 0.023). The results of this study provide a whole-system snapshot of how the rumen environment changes on diets differing in nutrient degradability and how the post-absorptive system adapts in response. Master of Science Over the last 50 years, dairy cattle have been bred to optimize milk production to meet growing population demands for milk and dairy products. The world population continues to grow and is projected to reach 9.7 billion people by 2050. Because of this growing population, there is an overwhelming need for dairy nutritionists to optimize the conversion of human inedible fibers into human edible food. The ruminant animal accomplishes this conversion through microbial fermentation of feedstuffs into volatile fatty acids (VFA), which account for approximately 70% of total energy available for meat, milk, and fiber production. Because rumen fermentation is a complex biochemical system, it is influenced by myriad factors including the substrate provided, the pH of the environment, and the absorptive and metabolic capacity of the rumen wall, among others. Although we understand how diet influences individual aspects of rumen fermentation, few studies have concurrently evaluated how diet influences the rumen chemical environment, the epithelium, and the resulting shifts in postabsorptive metabolism. Our study sought to understand the impacts of feedstuffs with different expected ruminally available starch and fiber supplies on these aspects of ruminant physiology. Six ruminally cannulated Holstein heifers were fed four different diets which used either beet pulp (low fiber ingredient) or timothy hay (high fiber ingredient), and ground corn (low starch ingredient) or ground barley (high starch ingredient). Heifers were fed each diet for a period of 18 days. From day 10 to day 14 of the period, nutrient degradability was assessed by incubating bags of feed in the rumen and conducting feed analysis after removed from the rumen. During the last four days of each period, rumen fluid samples, blood samples, muscle biopsies, and rumen papillae biopsies were collected. Feed analysis indicated that the starch sources differed in degradation rates (i.e. the speed of degradation) and fiber sources different in extent of rumen degradation (i.e. the percentage of feed degraded). Timothy hay caused greater concentrations of Total VFA, Total branched-chain VFA, acetate isobutyrate, and isovalerate. Timothy hay caused greater molar proportions of acetate and isovalerate. Corn caused greater molar proportions of propionate and valerate when barley caused greater molar proportions of butyrate. Rumen papillae biopsies were used to evaluate gene expression. Out of 14 genes, four were impacted by diet. Two rumen transporters responsible for the absorption of VFA had greater expression when animals were fed timothy hay diets versus beet pulp diets. Two metabolic genes also had greater expression due to timothy hay. The changes of both absorptive genes and metabolic genes is likely connected to the increased presence of VFA in the rumen. Lastly, blood acetate was increased, but there was not a specific ingredient or combination that caused the change. These results provide an overall snapshot of rumen fermentation characteristics and how changes in the rumen affect other biology.

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Steil, Lara. "Avaliação do uso de inóculos na biodigestão anaeróbia de resíduos de aves de postura, frangos de corte e suínos /." Araraquara : [s.n.], 2001. http://hdl.handle.net/11449/88047.

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Resumo: Investigou-se a influência da utilização de inóculos sobre a digestão anaeróbia de resíduos de aves de postura, frangos de corte e suínos em biodigestores modelo batelada com volume útil de 60 L operados à temperatura ambiente, por meio da caracterização do potencial e distribuição da produção de biogás ao longo do tempo, o estudo da redução de sólidos, a análise das características dos efluentes quanto à concentração de ácidos graxos voláteis e por meio da determinação do número mais provável (NMP) de coliformes fecais e totais nos afluentes e efluentes. Avaliou-se também a atividade metanogênica nos biodigestores com 10 % de inóculo. Foram testadas três concentrações de inóculo: 0, 10 e 15 %. Os resultados mostraram que os resíduos de aves de postura, frangos de corte e suínos são bons substratos para o processo de digestão anaeróbia, apresentando potenciais médios que variaram de 0,3828 a 0,4403 m3, de 0,3495 a 0, 3915 m3, e de 0,1949 a 0,4466 m3 de biogás por kg de ST adicionados, respectivamente para resíduos de aves de postura, frangos de corte e suínos. Com base em todos os parâmetros estudados, as concentrações de inóculo que promoveram melhores resultados foram 10 % para resíduos de aves de postura e frangos de corte, e 15 % para resíduos de suínos. O tratamento anaeróbio revelou-se eficiente na remoção de coliformes totais e fecais independente da concentração de inóculo, alcançando porcentagens médias de redução de NMP que variaram de 99,71 % de 1,09 x 102 a 100 %. A atividade metanogênica específica foi mais elevada nas amostras provenientes dos biodigestores operados com resíduos de aves de postura (0,0340 mmol CH4 g-1 SV h-1), seguida pelos resíduos de frangos de corte (0,0188 mmol CH4 g-1 SV h-1) e suínos (0,0029 mmol CH4 g-1 SV h-1). Estes resultados parecem estar mais associados aos teores...(Resumo completo, clicar acesso eletrônico abaixo) Abstract: This study was carried out in 60 L volume batch digesters at ambient temperature and investigated the inoculums concentration effects on anaerobic digestion of laying hens, poultry and piggery wastes through evaluation of potential and distribution of biogas production along the time, solids removal, analyze of volatile fatty acids efluent concentration and by monitoring the most probable number (MNP) of total and faecal coliforms in the inffluents and effluents. Specific methanogenic activity (SMA) into the 10 % inoculum digesters was also measured. Three inoculum concentrations (0, 10 and 15 %) were tested. Results showed that laying hens, poultry litter and piggery wastes are good substrats to anaerobic digestion. The potential biogas production varied from 0.03828 to 0.4403 m3, 0.3495 to 0.3915 m3 and 0.1949 to 0.4466 m3 of biogas kg-1 of total solids added, respectively for laying hens, poultry and piggery wastes. The best results for inoculum concentration were 10 % for laying hens and poultry wastes, and 15 % for piggery wastes. Anaerobic digestion was efficient for reduction of the most probable mean number of total and faecal coliforms. Reduction of MNP mean varied from 99.71 of 1,09 x 102 to 100 %. SMA test showed the best activity was from laying hens wastes (0,03400 mmol CH4 g-1 SV h-1), followed by poultry wastes (0,01877 mmol CH4 g-1 SV h- 1) and by piggery wastes (0,00293 mmol CH4 g-1 SV h-1). Results of SMA test appear to be most affected by volatile solids content of the samples than the best ability of the microrganisms to convert substrate. The best organic load rate for activity test were 0,25 g DQO g-1 SV. Orientador: Jorge de Lucas Junior Coorientador: Roberto Alves de Oliveira Banca: Rosana Filomena Vazoller Banca: Edson Aparecido Abdul Nour Mestre

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Cersosimo, Laura M., Melissa L. Bainbridge, Jana Kraft, and André-Denis G. Wright. "Influence of periparturient and postpartum diets on rumen methanogen communities in three breeds of primiparous dairy cows." BIOMED CENTRAL LTD, 2016. http://hdl.handle.net/10150/614742.

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Background: Enteric methane from rumen methanogens is responsible for 25.9 % of total methane emissions in the United States. Rumen methanogens also contribute to decreased animal feed efficiency. For methane mitigation strategies to be successful, it is important to establish which factors influence the rumen methanogen community and rumen volatile fatty acids (VFA). In the present study, we used next-generation sequencing to determine if dairy breed and/or days in milk (DIM) (high-fiber periparturient versus high-starch postpartum diets) affect the rumen environment and methanogen community of primiparous Holstein, Jersey, and Holstein-Jersey crossbreeds. Results: When the 16S rRNA gene sequences were processed and assigned to operational taxonomic units (OTU), a core methanogen community was identified, consisting of Methanobrevibacter (Mbr.) smithii, Mbr. thaueri, Mbr. ruminantium, and Mbr. millerae. The 16S rRNA gene sequence reads clustered at 3 DIM, but not by breed. At 3 DIM, the mean % abundance of Mbr. thaueri was lower in Jerseys (26.9 %) and higher in Holsteins (30.7 %) and Holstein-Jersey crossbreeds (30.3 %) (P < 0.001). The molar concentrations of total VFA were higher at 3 DIM than at 93, 183, and 273 DIM, whereas the molar proportions of propionate were increased at 3 and 93 DIM, relative to 183 and 273 DIM. Rumen methanogen densities, distributions of the Mbr. species, and VFA molar proportions did not differ by breed. Conclusions: The data from the present study suggest that a core methanogen community is present among dairy breeds, through out a lactation. Furthermore, the methanogen communities were more influenced by DIM and the breed by DIM interactions than breed differences.

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Li, Shihhui. "Angiopoietin-like protein 4 in bovine physiology." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/13107.

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Master of Science Department of Animal Sciences and Industry Barry Bradford Angiopoietin-like protein 4 (ANGPTL4) is a 55-kDa secreted glycoprotein which is an important factor for regulation of energy and lipid metabolism. Plasma ANGPTL4 has the ability to inhibit lipoprotein lipase (LPL) function by preventing it from catalyzing hydrolysis of lipoprotein triglyceride, which contributes to ANGPTL4’s ability to decrease fat storage. Furthermore, research in mice suggests that gut microbes suppress gastrointestinal ANGPTL4 production, and that decreased plasma ANGPTL4 concentrations promote fat storage. In our previous work, we found that bovine ruminal epithelial cells expressed ANGPTL4 to a greater extent than liver hepatocytes, which are usually considered the predominant source of circulating ANGPTL4. Therefore, 3 studies were conducted to evaluate the hypothesis that ruminal expression and plasma concentrations of ANGPTL4 could be influenced by alterations in ruminal fermentation. The first and second studies utilized dietary treatments intended to alter ruminal fermentability. Diets with relatively low or high forage content were fed to 12 non-lactating dairy cows (study 1) and 8 beef cattle (study 2) prior to collection of ruminal fluid and ruminal tissue samples. The results suggested that increasing the dietary concentrate decreased ruminal expression of ANGPTL4 but did not significantly alter plasma ANGPTL4 concentrations. The third study was designed to assess whether effects of diet fermentability on ruminal ANGPTL4 synthesis are mediated by changes in volatile fatty acid concentrations. In this study, 6 lactating cows were infused with acetate, propionate, or butyrate in a Latin square design. Results showed that ANGPTL4 expression was not significantly altered by volatile fatty acid infusions, but that expression was correlated with ruminal pH and total volatile fatty acid concentration. The mechanism by which ANGPTL4 regulates intracellular lipid metabolism also remains unclear. Although ANGPTL4 is known to associate with β1 and β5 integrins, it is unknown if these extracellular matrix proteins mediate the effects of ANGPTL4 in adipose tissue or muscle. The objective of the last experiment was to detect the ANGPTL4 receptor or mediator in muscle satellite cells and adipose tissue. We successfully expressed recombinant bovine ANGPTL4 with a cell free glycoprotein synthesis system. However, we did not detect the ANGPTL4–receptor complex following exposure to bovine adipose tissue explants or cultured bovine muscle satellite cells. Overall, these research projects determined that the ruminal ANGPTL4 production is influenced by fermentation, but it remains unclear whether fermentation products or direct host/microbe interactions are responsible. Finally, it will be important to identify the ANGPTL4 receptor or mediator to better understand the downstream regulatory mechanisms involved in mediating the metabolic effects of ANGPTL4.

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Pietrzyk, Julian Darius. "Use of microbial consortia for conversion of biomass pyrolysis liquids into value-added products." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31562.

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Lignocellulosic biomasses are considered promising feedstocks for the next generation of biofuels and chemicals; however, the recalcitrance of lignocellulose remains a barrier to its utilisation over conventional sources. Pyrolysis is the heating of biomass to several hundred degrees Celsius in the absence of oxygen, which can thermally depolymerise lignocellulose. Products of pyrolysis are a solid biochar, liquid bio-oil and syngas. Biochar has roles in both carbon sequestration and soil amendment however bio-oil has no defined use, despite a high concentration of fermentable sugars. Bio-oil is a complex organic microemulsion with a host of biocatalyst inhibitors that makes its microbial degradation a challenge. In this work, the use of aerobic cultures using microbial communities isolated from natural environments saw limited potential; however, the use of anaerobic digestion (AD) successfully generated a higher volume of biogas from reactors with bio-oil than controls. Biogas yield test reactors were set up with anaerobic digestate from a wastewater treatment plant as the substrate for degradation and conversion of bio-oils. Next-generation 16S rRNA gene sequencing was utilised to characterise the communities in the reactors while the ultrahigh resolution mass spectrometry technique of Fourier transform ion cyclotron resonance (FT-ICR) was used for characterisation of the chemical changes occurring during AD. Both sets of high-resolution data were additionally combined for multivariate analysis and modelling of the microbial genera that correlated best with the changes in digestate chemistry. This represents a novel analysis method for the microbial degradation of complex organic products. Bio-oil from common lignocellulosic feedstock was the most easily degradable by the AD communities, with significant inhibition observed when bio-oils from anaerobic digestate and macroalgae were used. Additionally it was found that the inclusion of biochars that were pre-incubated in anaerobic digestate prior to use in AD were capable of significantly reducing the lag time observed for biogas production in bio-oil-supplemented reactors. The addition of biochars that were not pre-incubated had no effect on biogas production. Specific inhibition of methanogenesis was also capable of causing the digestates to accumulate volatile fatty acids (VFAs) as a product of greater value than biogas. Scale-up experiments will be required to confirm the precise practicalities of the addition of bio-oil to AD as well as to establish the potential for isolation and purification of VFAs.

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White, Mallory Beth. "In ovo and feed application of probiotics or synbiotics and response of broiler chicks to post-hatch necrotic enteritis." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103632.

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Immediately post-hatch, broiler chicks are exposed to microbes that begin colonizing the gut, including environmental pathogens. One of the costliest enteric diseases in broiler production is necrotic enteritis (NE), caused by the ubiquitous opportunistic bacteria Clostridium perfringens (CP). With the worldwide reduction in antibiotic growth-promoters (AGPs), there is increased interest in natural alternatives to reduce disease and improve broiler health. The overall objective of the studies described herein was to apply probiotics or synbiotics to birds by in ovo application or orally before they leave the hatchery, then evaluate bird performance and various intestinal responses. Data were analyzed in JMP with LS Means to separate means with significance assigned at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. The first 21-day (D) study used 480 male Cobb 500 broilers randomly divided into one of four treatments using a 2x2 factorial design: a no-additive control (CTRL), a one-time oral application of synbiotic at the hatchery fed a basal diet (HS), an oral application of water at the hatchery with dietary synbiotics (DS), and a hatchery synbiotic plus dietary synbiotic (HSDS). Performance was measured on day-of-hatch (DOH), D3, D7, D14, and D21. mRNA abundance of various intestinal markers was measured at D7 and D21, including tight junction proteins ZO-1, ZO-2, and CLD-1; nutrient transporters SGLT1 and PepT1; and immune response markers TLR2, TLR4, and IL-10. HS lowered feed intake (FI) and feed conversion ratio (FCR) without lowering body weight (BW) from D14-21. There was greater abundance of PepT1 mRNA (P ≤ 0.1) and IL-10 mRNA (P ≤ 0.05) on D21 in HSDS. Second, a 21-day pilot study with 480 male and female Cobb 500 broilers was conducted to determine the optimum in ovo dosage level of a probiotic or synbiotic (PROB or SYNB) applied at embryonic day 18 (E18) with subsequent NE challenge using seven treatments: in ovo application of sterile water (CTRL), low (PROB-L or SYNB-L: 1x105 CFU), medium (PROB-M or SYNB-M: 1x106 CFU), or high (PROB-H or SYNB-H: 1x107 CFU) probiotic or synbiotic doses dissolved in sterile water. Performance measurements were taken on DOH, D4, D8, D14 and D21. On D8, NE lesion scores were not impacted by treatment. D8 ileal samples were taken for mRNA abundance of TLR4, IL-10, IL-1β, AvBD8, AvBD10, and AvBD13. SYNB-H had higher abundance of AvBD10 mRNA compared to CTRL (P ≤ 0.1), and higher IL-1β mRNA compared to SYNB-L (P ≤ 0.05). PROB-H and SYNB-H had better performance than the low and medium doses, but were not better than the CTRL. The high doses were chosen for subsequent studies. Third, a longer 42-day study using 1,630 Ross 708 male and female broilers was conducted consisting of the following six treatments. A negative control (NC): sterile water in ovo fed basal corn/soybean meal mash diet without NE challenge; antibiotic growth-promoter (AGP+): sterile water in ovo fed basal diet with virginiamycin (0.5 kg/MT) as an AGP with NE challenge; NC+: same as NC plus NE challenge; SI+: synbiotic in ovo fed the basal diet and NE challenged; SD+: sterile water in ovo fed basal diet supplemented with synbiotic (0.5 kg/MT feed) and NE challenged; and SID+: synbiotic in ovo fed basal diet with synbiotic (0.5 kg/MT feed) with NE challenge. Cumulatively, SID+ had lower FI and FCR than NC+, but no change in BW or BWG. The combination treatment (SID+) often had an additive effect compared to SD+ or SI+ alone on mRNA abundance and D7 cecal fatty acid profiles. SD+ and SID+ also had higher D42 lean:fat ratios compared to NC+. Last, a 42-day study was conducted using 1,630 male and female Ross 708 broilers and the in ovo application of probiotics and subsequent NE challenge with five treatments. NC: sterile water in ovo, fed basal corn/soybean meal mash diet without NE challenge; AGP+: sterile water in ovo, fed basal diet with virginiamycin (0.5 kg/MT of feed) as AGP with NE challenge; NC+: NC treatment, with NE challenge; PI+: probiotic in ovo, fed basal diet, with NE challenge; PD+: sterile water in ovo, fed basal diet supplemented with probiotic (1.3 kg/MT of feed), with NE challenge. The use of probiotics in this study had little effect on performance, lean:fat ratios, and cecal fatty acid profiles, but PD+ increased mRNA abundance of D14 TLR2, D14 TNF-α, and D42 LEAP2 in cecal tonsils compared to controls. PI+ increased mRNA abundance of D7 and D42 MUC2, D7 LEAP2, and D42 TNF-α in the ileum. PI+ increased mRNA abundance in the cecal tonsils of D7 TLR2 and D42 TNF-α. These studies yielded interesting results about probiotics and synbiotics during a NE challenge by evaluating performance, intestinal immune responses, and fatty acid profiles in the ceca of broilers. In conclusion, the probiotic in this study did not improve broiler health during a NE challenge, but synbiotic use in ovo and continuation in the feed showed improvement over in ovo or dietary application alone. Synbiotic improved FCR over a challenged control, and altered mRNA abundance in the small intestine. Doctor of Philosophy The poultry industry is one of the most popular animal protein sources worldwide. As with any livestock operation, industry goals include optimizing animal health and well-being, maximizing animal productivity, and producing quality products in the most cost effective manner. Improvements in genetics, nutrition, and management have increased productivity and cut costs. One important application was the low-level use of antibiotics in feed. These medications reduced the risk of disease outbreak in flocks, which led to healthier birds and improved growth rates. However, when global concern of antibiotic resistance in human medicine came to light, both the livestock industry and governing bodies implemented voluntary and mandatory reduction or elimination of antibiotics. Previously, these important antibiotics helped to control costly diseases. As they are removed, alternatives to antibiotics will be important in disease control and prevention. A major group of alternatives to antibiotics in poultry includes probiotics, prebiotics, and synbiotics. Probiotic bacteria are considered 'good bacteria' in the gut, and provide various health benefits to the host. Prebiotics are non-living substances that support the growth of healthy bacteria. A synbiotic is the combination of both probiotics and prebiotics in a single application method. The goal of this research project was to give probiotics or synbiotics to broiler chicks and evaluate their potential benefits and effects on bird performance and the immune response. Ideally, applying probiotic bacteria as early as possible might translate into early colonization of the gut with healthy bacteria. This included oral application of synbiotics at the hatchery, or by safely injecting them into part of the egg that is swallowed by the chick embryo before hatch. This egg application, or in ovo application, is a safe, effective, widely-practiced method of vaccinating chicks to jumpstart their defense against disease. By vaccinating them in ovo, they can start to prime the immune system before they even hatch. Applying probiotics in ovo may improve health after early gut colonization with beneficial microbes. Numerous studies on natural alternatives to antibiotics have been conducted, with varying results. Results of this research indicate that in ovo application of probiotics and synbiotics is safe. Birds that received probiotics in the feed often performed similar to those that received none. However, the in ovo use of synbiotics combined with the continued use in the feed after hatch improved efficiency in broilers during an intestinal disease challenge and improved various aspects of gut function. Overall, as antibiotics are phased out, using probiotics and synbiotics may improve poultry health, but continued research will help understand the optimum ways to use them.

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McMurphy, Casey Paul. "Effects of Humic/Fulvic Acid on Rumen Fermentation in Holstein Steers." Thesis, The University of Arizona, 2007. http://hdl.handle.net/10150/193335.

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Six ruminally fistulated steers (average BW 317 kg) were used in a 5 X 5 + 1 Latin Square design to determine effects of humic/fulvic acid (HFA) on serum urea nitrogen (SUN), rumen pH, rumen ammonia nitrogen (RAN), and rumen VFA production in Holstein steers. Treatments included a control (0%), 0.5, 1.0 or 1.5% HFA, and a diet containing monensin (33 mg/kg). A quadratic feed intake response was observed; with intake lowest for 0.5 and 1.0 and highest for 1.5 relative to control steers. No treatment x time interaction was observed for RAN, pH, SUN, total VFA or individual VFA. No treatment differences were observed for total VFA concentrations (mM), or for molar proportion of acetate, propionate, butyrate or valerate. A quadratic response was observed for butyrate and isovalerate. However, HFA does not alter rumen fermentation in the same mode of action as monensin.

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Steil, Lara [UNESP]. "Avaliação do uso de inóculos na biodigestão anaeróbia de resíduos de aves de postura, frangos de corte e suínos." Universidade Estadual Paulista (UNESP), 2001. http://hdl.handle.net/11449/88047.

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Made available in DSpace on 2014-06-11T19:23:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-09-27Bitstream added on 2014-06-13T19:08:56Z : No. of bitstreams: 1 steil_l_me_araiq.pdf: 799428 bytes, checksum: ea2cd9b8adbc44bdd76ac6b53c7d3a09 (MD5) Investigou-se a influência da utilização de inóculos sobre a digestão anaeróbia de resíduos de aves de postura, frangos de corte e suínos em biodigestores modelo batelada com volume útil de 60 L operados à temperatura ambiente, por meio da caracterização do potencial e distribuição da produção de biogás ao longo do tempo, o estudo da redução de sólidos, a análise das características dos efluentes quanto à concentração de ácidos graxos voláteis e por meio da determinação do número mais provável (NMP) de coliformes fecais e totais nos afluentes e efluentes. Avaliou-se também a atividade metanogênica nos biodigestores com 10 % de inóculo. Foram testadas três concentrações de inóculo: 0, 10 e 15 %. Os resultados mostraram que os resíduos de aves de postura, frangos de corte e suínos são bons substratos para o processo de digestão anaeróbia, apresentando potenciais médios que variaram de 0,3828 a 0,4403 m3, de 0,3495 a 0, 3915 m3, e de 0,1949 a 0,4466 m3 de biogás por kg de ST adicionados, respectivamente para resíduos de aves de postura, frangos de corte e suínos. Com base em todos os parâmetros estudados, as concentrações de inóculo que promoveram melhores resultados foram 10 % para resíduos de aves de postura e frangos de corte, e 15 % para resíduos de suínos. O tratamento anaeróbio revelou-se eficiente na remoção de coliformes totais e fecais independente da concentração de inóculo, alcançando porcentagens médias de redução de NMP que variaram de 99,71 % de 1,09 x 102 a 100 %. A atividade metanogênica específica foi mais elevada nas amostras provenientes dos biodigestores operados com resíduos de aves de postura (0,0340 mmol CH4 g-1 SV h-1), seguida pelos resíduos de frangos de corte (0,0188 mmol CH4 g-1 SV h-1) e suínos (0,0029 mmol CH4 g-1 SV h-1). Estes resultados parecem estar mais associados aos teores... This study was carried out in 60 L volume batch digesters at ambient temperature and investigated the inoculums concentration effects on anaerobic digestion of laying hens, poultry and piggery wastes through evaluation of potential and distribution of biogas production along the time, solids removal, analyze of volatile fatty acids efluent concentration and by monitoring the most probable number (MNP) of total and faecal coliforms in the inffluents and effluents. Specific methanogenic activity (SMA) into the 10 % inoculum digesters was also measured. Three inoculum concentrations (0, 10 and 15 %) were tested. Results showed that laying hens, poultry litter and piggery wastes are good substrats to anaerobic digestion. The potential biogas production varied from 0.03828 to 0.4403 m3, 0.3495 to 0.3915 m3 and 0.1949 to 0.4466 m3 of biogas kg-1 of total solids added, respectively for laying hens, poultry and piggery wastes. The best results for inoculum concentration were 10 % for laying hens and poultry wastes, and 15 % for piggery wastes. Anaerobic digestion was efficient for reduction of the most probable mean number of total and faecal coliforms. Reduction of MNP mean varied from 99.71 of 1,09 x 102 to 100 %. SMA test showed the best activity was from laying hens wastes (0,03400 mmol CH4 g-1 SV h-1), followed by poultry wastes (0,01877 mmol CH4 g-1 SV h- 1) and by piggery wastes (0,00293 mmol CH4 g-1 SV h-1). Results of SMA test appear to be most affected by volatile solids content of the samples than the best ability of the microrganisms to convert substrate. The best organic load rate for activity test were 0,25 g DQO g-1 SV.

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Domingos, Joana Margarida Bendada. "Acidogenic digestion of effluents of the cheese industry in packed bed biofilm reactors." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10648.

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Dissertation for the Master degree in Biotechnology The main goal of the present work was to study the production of volatile fatty acids (VFAs) from cheese whey powder (CWP) by employing a packed bed bioreactor (PPBR) for the anaerobic acidogenesis. First experiments were performed in 100-mL Pyrex bottles to study the acidogenesis trends, namely: lactose consumption, VFAs and biogas production and composition. These tests were done with freely suspended-cells (control experiment) and with immobilized cells using granular activated carbon (AC) and ceramic cube Vukopor S10 supports. The utilized inoculum – an acidogenic mix consortium- belongs to an analogous CWP digestion process in which a different culture system is being studied. Therefore, the incubations conditions were the same as for that culture system: 20 g/L of CWP (corresponding to 15 g/L lactose), 37ºC and pH 6. The observed trend consisted on lactose consumption, lactic acid formation (as an intermediate product) and from this VFAs production. The best yield was obtained when Vukopor was used (87% against 30% for AC); after 9 days the VFAs was (g/L): acetic (1.6), propionic (2.4); butyric (6.6) acids. The mentioned preliminary studies allowed selecting the operational hydraulic retention time(HRT) for the bioreactors. Two recirculate 1-liter PBBR one filled with Vukopor and other with AC were developed. CWP concentration, pH and temperature were the same as in the microcosm experiment. Both were operated in batch and continuous. In first batch performed in PBBR-Vuko it was achieved 6 g/L of propionic. However a loss of capability of producing it was observed during continuous operation. It was ascribed to a wash-out of related strains. With PBBR-Vuko were tested two different hydraulic retention times (HRT), 9 and 6 days, instead for PBBR-AC only HRT of 9 days. The yields for PBBRVuko were the same as at the microcosms scale, 80% for both HRT. On the other hand, the yield for PBBR-AC was 20%, this is a confirmation that AC was not the proper support even at a 1-L scale. Additionally to immobilization study, it was also set up a bioreactor with freely suspended cells. In this last mentioned bioreactor when a HRT of 6 days was set up it was observed a decrease in the VFAs yield to 44%. From this, it was concluded that the immobilization is an advantage for the VFAs production.

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39

Turon, Violette. "Coupling dark fermentation with microalgal heterotrophy : influence of fermentation metabolites mixtures, light, temperature and fermentation bacteria on microalgae growth." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS201/document.

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La production de microalgues en hétérotrophie présente plusieurs avantages pour la production de biocarburants par rapport à la production autotrophe, comme une productivité plus importante en termes de biomasse et de lipides. Cependant, le développement industriel de ce procédé est limité par les coûts de productions associés au substrat organique (i.e. glucose) et à ceux liés à la stérilisation des fermenteurs. Les effluents de fermentation sombre, composés principalement d’acétate et de butyrate, pourraient être utilisés comme milieux de culture peu onéreux pour la culture hétérotrophe ou mixotrophe de microalgues. Les objectifs de cette thèse étaient i) de mieux appréhender la croissance algale sur des mélanges variés d’acétate et de butyrate en fonction de la présence ou l’absence de lumière et de la température de croissance et ii) d’évaluer la faisabilité d’utiliser des effluents de fermentation non stérilisés pour soutenir la croissance de microalgues oléagineuses. Tout d’abord, un modèle basé sur des bilans de masse a été construit afin de caractériser la croissance hétérotrophe de Chlorella sorokiniana et Auxenochlorella protothecoides (taux de croissance et rendements) sur des mélanges d’acétate et de butyrate. Les résultats ont montré que le rapport acétate:butyrate et la concentration en butyrate étaient deux paramètres clés pour soutenir la croissance hétérotrophe. Puis, il a été démontré que la présence de lumière et l’utilisation d’une température suboptimale (30 °C) pour la croissance algale permettaient de réduire l’inhibition du butyrate en permettant une production de biomasse autotrophe ou en améliorant la croissance sur acétate. Enfin, il a été montré que les microalgues peuvent être compétitives sur l’acétate lors de la croissance sur des effluents bruts de fermentation sombre en présence de bactéries fermentaires, grâce à la croissance rapide des microalgues sur acétate (1.75 j-1) et à un changement drastique des conditions de culture peu favorables à la croissance des bactéries d’origine fermentaire Growing microalgae in heterotrophic mode present several advantages over autotrophic mode such as a higher productivity in terms of biomass and lipids for biofuels production. Nevertheless, this process is limited by the production cost associated with the organic substrate (i.e. glucose) and fermenters sterilization costs. Dark fermentation effluents, mainly composed of acetate and butyrate, could be used as a low-cost medium to grow microalgae heterotrophically or mixotrophically. The aims of this PhD were i) to optimize microalgae growth on various mixtures of fermentations metabolites using the presence or absence light and different cultivation temperatures and ii) to assess the feasibility of using unsterilized fermentation effluents. First, a model based on mass balance was built to characterize heterotrophic growth rates and yields when Chlorella sorokiniana and Auxenochlorella protothecoides were supplemented with different mixtures of acetate and butyrate. Results showed that the acetate:butyrate ratio and the butyrate concentration per se were two key parameters for promoting heterotrophic growth. Then, further studies showed that the presence of light and the use of suboptimal temperature (30 °C) could reduce the butyrate inhibition on growth by either triggering autotrophic production of biomass or enhancing growth on acetate. Finally, it was shown that microalgae could outcompete fermentation bacteria for acetate when growing on raw dark fermentation effluents, thanks to a fast algal growth on acetate (1.75 d-1) and a drastic change of culture conditions to the detrimental of bacterial growth

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Bowman, Tessa Leigh. "Analysis of factors affecting volatile compound formation in roasted pumpkin seeds with selected ion flow tube mass spectrometry (SIFT-MS)." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306242976.

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41

Mayeux, Bruno. "Ecologie microbienne et métabolisme associé : étude de l'eau interstitielle et de la roche argileuse du Callovo-Oxfordien dans le Laboratoire de Recherche Souterrain de l’Andra (Meuse/Haute-Marne)." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4783/document.

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Dans le cadre des recherches de l'ANDRA sur le confinement en couche géologique profonde de déchets radioactifs, une étude microbiologique a été menée sur l'eau interstitielle et l'argile du Callovo-Oxfordien (–490m, 165 millions d'années). Deux types d'études ont été menés, culturale et moléculaire.Malgré différentes tentatives d'extractions, et comme pour les études antérieures effectuées, aucun ADN n'a pu être extrait au cours de ce travail. Par contre, une approche culturale a permis de mettre en évidence la présence d'une microflore peu dense mais viable et métaboliquement assez variée : neuf espèces aérobies dont quatre facultatives et deux anaérobies strictes, de différents types métaboliques : sulfato-réducteur, réducteur de Fe(III), fermentaire et oxydation complète des substrats en CO2. Au vu des disponibilités in-situ en sources de carbone (SC) et d'énergie nécessaires à la croissance bactérienne, la production d'acétate et autres acides gras volatils ainsi que la production d'hydrogène pourraient potentiellement être actifs dans le Cox. L'étude des produits du métabolisme a permis d'identifier plusieurs agents biotiques (dont H2S) ayant potentiellement une activité biocorrosive. Par ce travail il apparait fondamental que la composante biologique soit prise en compte dans la conception du stockage, afin notamment d'éviter ou de limiter tout apport de matière organique exogène à la formation argileuse. Cette prise en compte biologique apparait cruciale pour tenter de restreindre le réseau trophique bactérien à ces conditions initiales, celles qui sont potentiellement présentes sur le site de stockage, qui concernent les seules SC et d'énergie autochtones In the framework of research of ANDRA about reversible deep geological radioactive waste, a microbiological study was conducted on pore water and Callovo-Oxfordian clay layer (-490m and 165 million years). Two types of studies were conducted, a cultural approach and a molecular approach.Despite various attempts of extraction, and as for the previous, no DNA could be extracted in this work. However, the cultural approach has highlighted the presence of a sparse microflora but viable and metabolically quite varied: nine aerobes species including four facultative anaerobes and two strictly anaerobes. They represent different metabolic types: sulfate-reducing, iron-reducing, fermentative and complete oxidation of substrates into CO2. In view of the availability of in-situ sources of carbon and energy required for bacterial growth, the production of acetate and other volatile fatty acids as well as hydrogen production could potentially be active in the clay layer of Cox and open to varied bacterial growth.The study of metabolic products has also identified several biotic agents (including hydrogen sulfide) having a potentially biocorrosive activity. Through this work it appears that the biological component is to be taken into account in the design of radioactive waste storage, in particular to avoid or minimize any contribution of exogenous organic matter in the clay formation.This biological consideration appears crucial to attempt to restrict bacterial trophic network on these initial conditions, that is to say those that are potentially present on the storage site, that concern solely autochthonous carbon and energy sources

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Elfving, Erik. "Hydrolys av primärslam för förbättrande av biologisk fosforreduktion vid behandling av hushållsavloppsvatten [Hydrolysis of primary sludge for enhancement of biological phosphorus removal in household wastewater]." Thesis, Linköping University, Department of Water and Environmental Studies, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-3997.

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Hammarby Sjöstad is a new district of southern Stockholm built with focus on reduced environmental impact by recirculation of materials and sustainability. The environmental goals aim to cut the water consumption by half and a separate storm water treatment. Thus, the wastewater will be more concentrated and will originate from the households only. The Sjöstad project includes the idea of a local treatment plant for the household wastewater. To evaluate this possibility, Sjöstadsverket, an experimental treatment plant was constructed. New wastewater treatment processes are tested and evaluated and compared to conventional methods including both aerobic and anaerobic treatment processes.One of the aerobic treatment processes includes enhanced biological phosphorus removal (EBPR or Bio-P) as the method for the removal of phosphorus. In biological phosphorus removal the wastewater is alternately being exposed to anaerobic and aerobic conditions, which favours a certain bacteria, which can accumulate more phosphorus than is required for their growth. For this phosphorus accumulation the bacteria need volatile fatty acids (VFA) to cover their energy demand, but normally there is a shortage in VFA in the incoming wastewater.The main purpose of this master thesis work has been to create the best possible conditions in order to produce VFA by hydrolysis and fermentation of primary sludge. In this way the organic material in the incoming wastewater can be used in biological phosphorus removal.The sludge temperature, total solids (TS) and retention time are regarded as important parameters for a successful biological phosphorus removal and a laboratory study was set up to investigate these conditions for the wastewater at the Hammarby Sjöstad experimental plant. These laboratory-scale hydrolysis experiments showed that high temperature and high TS favours VFA-production. The results have also shown that four to five days retention time is suitable at a process temperature higher than 23°C, but also that the retention time likely should be extended at lower temperatures.In a full-scale process experiment, primary sludge was pumped from a primary clarifier to a hydrolysis tank and then back to the primary clarifier. The hydrolysis gave rise to increased VFA-production when TS was increased. A temperature difference between the primary sludge and the hydrolysis sludge of 3°C was observed. The reason behind the difference has not been determined, but is considered important, since the temperature affects the VFA-production. Further on, analyses with gas chromatograph (GC) have shown that acetate has been the most frequently occurring VFA, although significant levels of other VFA, such as propionate, has also been detected.Phosphorus release tests in laboratory-scale, where phosphorus was released during an anaerobic phase and taken up during an aerobic phase, proved that biological phosphorus removal occurred at the full-scale experimental train.The full-scale hydrolysis experiment has shown that the VFA contribution by the hydrolysis tank to the biological phosphorus removal was low. The main reason is that the sludge-flow through the hydrolysis tank has been insignificant compared to the incoming wastewater flow. The problem is most likely connected to the incoming wastewater characteristics, since the low share of suspended solids (SS) entailed that not enough organic material in the primary clarifier settled. I figur 57 på sidan 76 stämmer inte trendlinjernas ekvationer i den tryckta versionen. Dessa är nu korrigerade i den elektroniska versionen, så att rätt ekvationer finns i den aktuella figuren.

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43

Borges, Luiz Felipe de Onofre. "Efeitos da enramicina ou da monensina sódica sobre a fermentação ruminal e a digestão total em bovinos." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/10/10135/tde-23032007-183536/.

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Foram objetivos do presente experimento estudar os efeitos da administração da enramicina, em comparação com a monensina sódica, sobre a fermentação ruminal e a digestibilidade total em bovinos. Doze fêmeas bovinas não-gestantes e não-lactantes (675 kg ± 63 de PV) foram distribuídas inteiramente ao acaso aos três tratamentos formados por um grupo controle (ausência de antibiótico), um grupo tratado com enramicina (antibiótico não-ionóforo) e outro tratado com monensina (antibiótico ionóforo). A enramicina foi administrada na dose de 20 mg/animal/dia e a monensina na dose de 300 mg/animal/dia. O experimento teve duração total de 21 dias, sendo os 10 últimos destinados à aplicação do marcador (15 g de óxido crômico/animal/dia) e os últimos 5 dias destinados à coleta de fezes e amostragem dos alimentos. O 21º dia foi utilizado para colheitas de líquido ruminal realizadas às 0, 2, 4, 6, 8, 10 e 12 horas após a 1a refeição para determinação dos AGVs, pH e nitrogênio amoniacal. A monensina aumentou a concentração total de AGVs no tempo 12 horas após a alimentação e diminuiu a relação acético:propiônico nos tempo 0 e 6 h, em relação à enramicina, mas não em relação ao controle. Nenhum dos antibióticos testados alterou a proporção molar dos ácidos acético, propiônico e butírico, bem como o pH ou a concentração ruminal de nitrogênio amoniacal. Também não alterou o comportamento de consumo, avaliado em atividades de alimentação, ruminação e ócio. Nenhum dos antibióticos testados alterou a digestibilidade da matéria seca, proteína bruta, extrato etéreo, extrativo não nitrogenado, fibra bruta, fibra em detergente ácido, fibra em detergente neutro, amido, energia bruta ou os nutrientes digestíveis totais The objective of this trial was to study the effects of enramycin administration, compared to sodium monensin, on ruminal fermentation and on total digestibility of diet nutrients in bovine. Twelve non-pregnant and non-lactating cows (675 ± 63 kg of BW) were randomly assigned to three treatments: control group (non-antibiotic), enramycin-treated group (non-ionophore antibiotic) and monensin-treated group (ionophore antibiotic). Treatments were 20 mg/animal/day of enramycin or 300 mg/animal/day of monensin. Trial lasted 21 days, the last 10 used for external marker administration (15 g of chromic oxide/animal/day) and the last 5 for feces collection and feed sampling. The 21st day was used for ruminal fluid sampling at 0, 2, 4, 6, 8, 10 and 12 hours after 1st meal to determine VFA, pH and ammoniacal nitrogen. Monensin increased total VFA concentration 12 h after feeding and decreased the acetic:propionic ratio at times 0 and 6 h, in relation to enramycin, but not when compared to control. The two antibiotics tested did not influence the molar proportion of acetic, propionic or butiric acids, pH, ammoniacal-N concentration, or dry matter intake and intake behavior, evaluated during activities of feeding, rumination and idleness. The two antibiotics tested did not alter the digestibility of dry matter, crude protein, ether extract, nitrogen-free extract, crude fiber, acid detergent fiber, neutral detergent fiber, starch, gross energy and total digestible nutrients (TDN), or the intake of digestible dry matter or TDN

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44

Panthi, Sudan Raj. "Effect of Arsenic on the Denitrification Process in the Presence of Naturally-Produced Volatile Fatty Acids and Arsenic Removal by New Zealand Iron Sand (NZIS)." Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2009. http://hdl.handle.net/10092/3199.

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This thesis is comprised of two phases; the first phase concerns the effect of arsenic on the denitrification process in the presence of naturally-produced volatile fatty acids (VFAs); while the second phase evaluates the arsenic removal efficiency of New Zealand Iron Sand (NZIS) by adsorption. To accomplish the first phase of the study, VFAs were first produced naturally in an acid-phase anaerobic digester by using commercially-available soy flour. Secondly, a denitrifying biomass was cultivated in a sequencing batch reactor (SBR) using domestic wastewater as a feed solution. Finally, a series of biological denitrification batch tests were conducted in the presence of different concentrations of arsenic and nitrate. As mentioned, the VFAs were generated from an anaerobic digester using 40 g/L soy solution as a synthetic feed. The digester was operated at a solids retention time (SRT) and hydraulic retention time (HRT) of 10 days. The pH of the digester was measured to be 4.7 to 4.9 while the mean temperature was 31 ± 4 °C; however, both these parameters were not controlled. In the effluent of the digester, a mean VFA concentration of 5,997 ± 538 mg/L as acetic acid was achieved with acid speciation results of acetic (33 %), propionic (29 %), butyric (21 %), iso-valeric (5%) and n-valeric acid (12 %). The specific VFA production rate was estimated to be 0.028 mg VFA as acetic acid/mg VSS per day. The effluent sCOD was measured to be 14,800 mg/L (27.9 % of the total COD), as compared to 9,450 mg/L (16.8 % of total COD) in the influent of the digester. Thus, the COD solubilization increased by 11.1 % during digestion yielding a specific COD solubilization rate of 0.025 mg sCOD/mg VSS per day. The extent of the digestion process converting the substrate from particulate to soluble form was also evaluated via the specific TOC solubilization rate (0.008 mg TOC/mg VSS per day), and VSS reduction percentage (17.7 ± 1.8 %). A denitrifying biomass was developed successfully in an SBR fed with domestic sewage (100 % denitrification was achieved for the influent concentration of sCOD = 285 ± 45 mg/L and NH₄⁺-N = 32.5 ± 3.5 mg/L). A mean mixed liquor suspended solids (MLSS) of 3,007 ± 724 mg/L and a mean SRT of 20.7 ± 4.4 days were measured during the period of the research. The settleability of the SBR sludge was excellent evidenced by a low sludge volume index (SVI) measured to be between 50-120 mL/g (with a mean value of 87 ± 33 mL/g) resulting in a very low effluent solids concentration (in many cases less than 20 mg/L). Several preliminary tests were conducted to estimate the right dosage of VFAs (digester effluent), nitrates and arsenic to be added and to confirm the occurrence of denitrification in an appropriate time frame of 4-6 h. From these tests, an optimum C/N ratio was observed to be somewhere between 2 to 4, somewhat higher than all the theoretical C/N ratios required for a complete denitrification using the four major VFAs identified in the digester effluent. During the denitrification batch tests, it was also observed that some NO₃⁻- N was removed instantaneously by reacting with As (III) (As₂O₃); while an increase in alkalinity of around 5.60 mg as CaCO₃ produced per mg NO₃⁻- N reduction was also observed. This latter number was very close to the theoretical value of alkalinity production (i.e. 5.41 mg as CaCO₃ per mg NO₃⁻- N). The effect of arsenic on the denitrification process was evaluated by observing the specific denitrification rate in series of denitrification batch tests (with different concentrations of arsenic). Results from the denitrification batch tests showed that there was a clear effect for both As (III) and As (V) on denitrification. In particular, the specific denitrification rate fell from 0.37 to 0.01 g NO₃⁻- N /g VSS per day as the concentration of As (III) increased from 0 to 50 mg/L. In contrast, there was comparatively less effect for As (V); i.e. only a 37 % decrease in the specific denitrification rate (from 0.34 g NO₃⁻- N /g VSS per day to 0.23 g NO₃⁻- N /g VSS per day) when the initial arsenic concentration increased from 0 to a very high level of 2,000 mg/L. The effects of both the As (III) and As (V) forms of inorganic arsenic on the denitrification rate were further quantified by constructing exponential equation models. It was suspected that the effect of As (III) on denitrification was more substantial than the effect of As (V) because of the former’s toxicity to microbes. Finally, the fate of arsenic was tracked by examining bacterial uptake. During the normal denitrification batch tests (i.e. designed for evaluation of the effect of arsenic on denitrification), no significant arsenic removal was observed. However, additional batch tests with a comparatively low concentration of biomass revealed that the denitrifying biomass removed 1.35 µg As (III) /g dry biomass and 2.10 µg As (V) /g dry biomass. In the second phase of this research, a series of arsenic adsorption batch tests as well as a column test were performed to examine the arsenic (As (III) and As (V)) removal efficiency of NZIS from an arsenic-contaminated water. The kinetics and isotherms for adsorption were analysed in addition to studying the effect of pH during the batch tests. Breakthrough characteristics for both As (III) and As (V) were studied to appraise the effectiveness of NZIS treating an arsenic contaminated water. Batch tests were performed with different concentrations of arsenic as well as at different pH conditions. A maximum adsorption of As (III) of approximately 90 % occurred at a pH of 7.5, while the As (V) adsorption reached its maximum value of 97.6 % at a very low pH value of 3. Both Langmuir and Freundlich Models were tested and found to fit with R² values of more than 0.92 in all cases. From the Langmuir adsorption model, the maximum adsorption capacity of NZIS for As (III) was estimated to be 1,250 µg/g, significantly higher (about three times) than for As (V) of 500 µg/g. In column tests, arsenic-contaminated water with total As concentration of 400 µg/L (in either form of As) were treated and a pore volume (PV) of 700 and 300 yielded a total arsenic level less than the WHO guideline value of 10 µg/L for As (III) and As (V) respectively; while, the breakthrough occurred after a throughput of approximately 3,000 PV of As (III) and 2,700 PV of As (V) with an average flow rate of approximately 1.0 mL/min.

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45

Facchin, Andrea. "New path for thermochemical-biological conversion with a power-to-material approach." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23117/.

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I sistemi termochimico-biologici si basano su due proprietà: la capacità dei processi termochimici di dissociare le macromolecole della biomassa producendo composti a basso peso molecolare, e l’abilità dei batteri di convertire substrati anche complessi in sostanze chimiche di valore. Questa tesi ha sviluppato un nuovo approccio metodologico per approfondire la possibilità di un accoppiamento diretto tra pirolisi e digestione anaerobica, allo scopo di produrre acidi grassi volatili (VFA), sinergicamente con l’utilizzo di idrogeno come fonte rinnovabile per aumentare il valore del prodotto finale. In primo luogo, è stata fatta un'ampia caratterizzazione del rendimento di COD e della composizione chimica dei prodotti di pirolisi che ha rivelato come più del 50% del COD della biomassa di partenza sia convogliato in sostanze chimiche biodisponibili. In secondo luogo, sono stati sviluppati tre reattori anaerobici a gocciolamento con diversi materiali di riempimento, incluso il biochar. I prodotti di pirolisi sono stati successivamente fermentati con e senza idrogeno, per valutarne, in via preliminare, la possibile conversione in VFA. I risultati suggeriscono che il biochar ha agito come promotore per la biotrasformazione dei prodotti di pirolisi in VFA, producendo una conversione del 35% rispetto al COD in input, mentre l'idrogeno ha dimostrato la capacità di stabilizzare le rese di VFA a catena lunga.

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46

Courtois, Noémie. "Etude du vieillissement de boues de papeterie utilisées pour la fabrication de briques de terre cuite : influence des produits de dégradation sur les caractéristiques céramiques des matériaux." Thesis, Bourgogne Franche-Comté, 2021. http://www.theses.fr/2021UBFCD003.

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Des boues de papier peuvent être incorporées au sein des mélanges industriels argileux pour l'élaboration de briques en terre cuite. Cette incorporation a plusieurs objectifs et avantages, notamment au niveau de l'optimisation du séchage des briques via l’effet hydrophile des fibres de papier, ainsi que pour la création de porosité au sein des briques améliorant leur résistance thermique. Or, certains phénomènes néfastes peuvent apparaître à l’échelle industrielle : fissuration des briques et apparition d'efflorescences (blanchiment de la surface des briques), notamment lorsque les boues de papier présentent un certain vieillissement. Cette thèse a pour but d'étudier et d'identifier les substances provoquant ces phénomènes et de définir les conditions dans lesquelles leur apparition est favorisée. Nous étudierons pour cela le vieillissement de boues de papier ainsi que leur incorporation à des mélanges argileux. L'influence de la nature et de l’état des boues de papier sur le comportement des produits finis sera ainsi étudiée via le façonnage et la caractérisation (paramètres physico-chimiques et céramiques) de mélanges recomposés argiles et boues de papier. Les AGV identifiés lors du vieillissement ont une influence, dépendant de la matière fibreuse (longueur des fibres, ratio cellulose/lignine), sur les caractéristiques céramiques des matériaux (diffusivité et séchage). Ces modifications peuvent conduire à l’apparition des défauts lorsqu’un seuil de 10 mg d’AGV/g de boues de papier, incorporées à 12% dans la phase argileuse, est dépassé. Enfin, une réflexion est menée sur les conditions optimales de stockage et d'utilisation permettant de réduire ou de contrôler l'apparition des phénomènes indésirables Paper sludge can be incorporated in industrial clayey mixtures used in fired-clay bricks formulation. This incorporation has several aims and benefits, especially for drying optimization of the products, due to hydrophilic effect of paper fibers, and creating porosity which improves the fired brick thermal insulation. However, some drawbacks may occur such as brick cracking or efflorescence (bleaching of brick surfaces), in particular when the added paper sludge presents a significant ageing. The purpose of this thesis consists in identifying the parameters responsible for cracks and efflorescence on the bricks and defining the conditions preventing the defects occurrence. Therefore, the ageing of paper sludges as well as their incorporation into clayey mixtures were studied. Several paper sludges of different compositions and degradation states were tested, and their impacts on the formulated bricks characteristics (physico-chemical and ceramic parameters) were investigated. Volatile Fatty Acids produced during paper sludge ageing were identified as key parameters to explain defect formations on the bricks, with a threshold value of 10 mg VFA/g of paper sludge, incorporated at 12% in the clay phase. Depending on the fibrous paper sludge characteristics (fiber length, cellulose/lignin ratio), VFAs have an influence on the water diffusivity and drying of the bricks. Finally, suggestions are made for the optimization of storage conditions of paper sludges before utilization and brick/paper sludge formulation. This would result in significant reduction of production defects

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47

Becker, Eduardo Garcia. "Suplementação com ácidos graxos de cadeia média na emissão de metano, produção e qualidade do leite em vacas lactantes." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/10873.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico Lipid additives used in the nutrition of dairy cows may affect both milk fat composition, as modifying the individual fatty acid profile, reducing methane emissions, becoming a sustainable practice for dairy cattle. To verify the effect of an additive based on medium chain fatty acids (MCFA) containing caproic acid, caprylic, capric, lauric and myristic, four treatments were tested: CTL (control without addition of MCFA), AGCM20 (5g MCFA), AGCM40 (10g MCFA) and AGCM80 (20g MCFA) on in vitro production gas (Experiment 1) and in the diet of lactating cows (Experiment 2). The bottles were distributed in a completely randomized design with repeated measurements over time and animals in triple latin square with four animals, four periods, four treatment, respectively. In Experiment 1 evaluated the production of gas, short chain fatty acids (SCFA) and methane (CH4); in Experiment 2 the productive parameters of milk and individual profile of fatty acids of milk fat. There was a significant decrease in gas production and methane (P<0.05), changing the profile of SCFA production in vitro treatment gas in AGCM40 and 80 compared with the control. No effects on productive parameters (P>0.05), however, were observed linear increase of C17:0 and C18: 3n6 (P<0.05) in the treatments AGCM20 and 80 respectively. It has been found that the use of MCFA 10 and 20g reduce the production of methane, without altering milk production and fatty acids of milk. Aditivos lipídicos utilizados na nutrição de vacas leiteiras podem afetar tanto a composição da gordura do leite, quanto modificar o perfil de ácidos graxos individuais, reduzindo as emissões de metano, tornando-se uma prática sustentável para pecuária leiteira. Para verificar o efeito de um aditivo a base de ácidos graxos de cadeia média (AGCM), contendo ácido capróico, caprílico, cáprico, láurico e mirístico, foram testados quatro tratamentos: CTL (controle, sem suplementação), AGCM20 (5g AGCM), AGCM40 (10g AGCM) e AGCM80 (20g AGCM) na produção in vitro gás (Experimento 1) e na dieta de vacas em lactação (Experimento 2). Os frascos foram distribuídos em um delineamento inteiramente casualizado com medidas repetidas no tempo e os animais em um triplo quadrado latino, com quatro animais, quatro períodos, quatro tratamentos, respectivamente. No experimento 1 foram avaliados a produção de gás, ácidos graxos de cadeia curta (AGCC) e metano (CH4); no Experimento 2 os parâmetros produtivos de leite e perfil individual dos ácidos graxos da gordura do leite. Houve redução significativa na produção de gás e metano (P<0,05), alterando o perfil de AGCC na produção in vitro gás nos tratamento AGCM40 e 80 em comparação com o controle. Não foram observados efeitos nos parâmetros produtivos (P>0,05), entretanto, foram observados aumentos lineares de C17:0 e C18:3n6 (P<0,05), nos tratamentos AGCM20 e 80 respectivamente. Foi constatado que o uso de 10 e 20g de AGCM reduz a produção de metano, não alterando a produção de leite.

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48

Alves, Teresa Cristina. "Efeitos de diferentes níveis de milho em grãos moídos (relação proteína:carboidratos não estruturais) em dietas para búfalos sobre o metabolismo no rúmen." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/74/74131/tde-24042007-085516/.

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As funções metabólicas dos bubalinos ainda não estão bem descritas, como em outros ruminantes e há carência de informação sobre o comportamento digestivo. A sincronização da degradação ruminal de proteína e amido propõe incrementar a produção de proteína microbiana no rúmen e a eficiência de utilização de energia, uma vez que as bactérias ruminais necessitam destes dois elementos disponíveis simultaneamente. Quatro búfalos fistulados no rúmen foram utilizados com objetivo avaliar os efeitos de dietas com diferentes níveis de milho em grãos moídos (0, 22, 37 e 49% na MS) em substituição ao feno de coast-cross, com ênfase na relação proteína:carboidratos não estruturais (1,02; 0,39; 0,30; 0,26), sobre o metabolismo ruminal. Os seguintes parâmetros foram avaliados: ingestão de matéria seca (IMS); degradabilidade da matéria seca e fibra em detergente neutro do feno de coast-cross e da matéria seca e proteína bruta do milho em grãos moído; concentração de amônia; produção de ácidos graxos voláteis (acético, propiônico e butírico); taxa de passagem de líquido; volume ruminal e pH no rúmen. Os animais foram delineados em Quadrado Latino (4x4). Houve aumento linear na IMS com aumento de milho em grãos na dieta. Foram observadas diferenças no metabolismo ruminal envolvendo a produção de ácidos graxos voláteis, pH, taxa de passagem do líquido ruminal e volume do rúmen entre os tratamentos e pouca influência dos tratamentos na produção de amônia e na cinética de degradabilidade ruminal. Os resultados permitiram concluir que, no geral, os bubalinos apresentam boa capacidade tamponante no rúmen com ligeira queda do pH com aumento da ingestão de milho em grãos moídos e que provavelmente os microrganismos ruminais dos búfalos têm boa capacidade em se adaptar a ambientes ruminais com diferentes relações PB:CNE. The metabolic functions of the buffaloes not yet are well described, as in other ruminants and have information lack on the digestive behavior. The synchronization of the ruminal degradation of protein and starch considers to increase the rumen microbial protein production and the efficiency of energy use, since the rumen bacteria needs of these two available elements simultaneously. Four rumen fistulated buffalos were used with objective to evaluate the effect of diets with different levels of ground grain corn (0, 22, 37 and 49% in the DM) in substitution to the coast-cross hay, with emphasis in the relation protein:no structural carbohydrates (1,02; 0,39; 0,30; 0,26) on the ruminal metabolism. The following parameters had been evaluated: dry matter intake (DMI); DM and NDF degradability of DM and NDF of the coast-cross hay and DM and CP of the ground grain corn; ammonia concentration; production of volatile fatty acids (acetic, propionic and butyric); outflow rate; ruminal volume and rumen pH. The animals were delineated in Latin Square (4x4) experiment. There was linear increase in the DMI with increasing level ground grain corn in the diet. Differences in the ruminal metabolism were observed involving the production of acid VFA, pH, liquid outflow rate and rumen volume among the treatments and small influence of the treatments in the ammonia production and the kinetic of ruminal degradability were observed. The results had allowed to conclude that, in the general, the buffaloes present good rumen buffering capacity with light fall of pH with increasing of the ingestion ground grain corn and that probably the microorganisms in the rumen of the buffalos have good capacity to adapt in the environments with different relations CP:NSC.

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49

Torres, Douglas Guedes Batista. "Produção de hidrogênio em reator anaeróbio de leito fixo e fluxo ascendente a partir de efluente de fecularia." Universidade Estadual do Oeste do Parana, 2014. http://tede.unioeste.br:8080/tede/handle/tede/193.

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Made available in DSpace on 2017-05-12T14:47:03Z (GMT). No. of bitstreams: 1 Douglas _Torres.pdf: 3616129 bytes, checksum: a4f03d06a9a51441bb0fbfebd263c6b0 (MD5) Previous issue date: 2014-02-20 Hydrogen is naturally formed in intermediate stages of anaerobic digestion and is subsequently consumed to generate products such as methane and hydrogen sulphide. So, in order to increase the energetic efficiency of gases produced in the system, it was necessary to separate hydrogen. It is essential to interrupt hydrogen consumption by methanogenic and sulphidegenic phases of anaerobic digestion process. As the effluent from cassava processing presents high concentration of sugars, there may be some possibility to favor the acidogenic digestion process, which provides better conditions to produce hydrogen gas and inhibit methanogenic archaea. Thus, this trial aims at evaluating hydrogen production from anaerobic digestion of wastewater from the cassava manufacturing process in an upflow anaerobic reactor, where bamboo was used as support medium. Four experimental runs (R1, R2, R3 and R4) were carried out in a 3.0 L plexiglass reactor, operated at 0.75 h-1 flow rate and Hydraulic Detention Time (HDT) of 4 hours. The assays were inoculated with 10% of the effective volume of an anaerobic sludge digester installed on a cassava industry at 95 °C for 15 min to eliminate microorganisms that produce methane. The cassava pH adjustment was managed to 6.0, but only at the R1 run. In R2, R3 and R4 runs, without any pH change, the values ranged from 3.74 to 4.47. The reactors showed a consumption average from total sugar superior at 80%, whose COD removals were 55.26, 15.27, 46.16 and 40.42% for R1, R2, R3 and R4, respectively. It was also observed that biogas flow decreasing provided greater biomass accumulation in the reactor. Thus, the results of HDT values were obtained by hydrodynamic essay of 3.75, 1.08, 1.83 and 2.43 for R1, R2 R3 and R4, respectively. It can also be observed that the process of hydrogen generation was associated with the metabolic route to generate butyric acid, since the increase of this product from acidogenesis resulted in higher amounts of hydrogen. It was also pointed out that the peak incidences of lactic and propionic acid concentrations in the effluent occurred simultaneously to the decreased production, which could indicate H2 consumption. The use of cassava without pH correction in R2, R3 and R4 resulted in lower productions of H2 maybe as a result of solventogenesis possibility that was recorded by the increase in butanol and ethanol production, which matched to the hydrogen flow reduction. The highest molar flow rates of H2 were observed in R1, with maximum value of 10.6mmolH2.h-1. R2 essay showed the highest percentages of hydrogen in biogas (45.37%) and maximum flow of 3.37 mmolH2.h-1, whose highest concentrations of calcium in cassava lots were used in that period. However, R3 and R4 reactors showed the highest flows (0.99 and 1.80 mmolH2.h-1). Thus, it should be highlighted the importance of correcting pH of cassava industry wastewater and monitoring alcohols and volatile fatty acids generated during this process. O hidrogênio é naturalmente formado em etapas intermediárias da digestão anaeróbia e é posteriormente consumido para geração de produtos como o metano e o ácido sulfídrico. Para possibilitar a separação do hidrogênio, em busca do aumento da eficiência energética dos gases gerados no reator, torna-se necessária a interrupção do consumo do hidrogênio pelas fases metanogênica e sulfetogênica do processo de digestão anaeróbia. Como o efluente do processamento da mandioca apresenta elevada concentração de açúcares, pode ocorrer o favorecimento do processo de digestão acidogênica, que proporciona melhores condições para a geração do gás hidrogênio e inibição das arqueias metanogênicas. Assim, o presente trabalho teve como objetivo geral avaliar a produção de hidrogênio a partir da digestão anaeróbia de efluente do processo de fabricação de fécula de mandioca (manipueira), em reator anaeróbio de leito fixo e fluxo ascendente, utilizando hastes de bambu como meio suporte. Foram realizados 4 ensaios experimentais (R1, R2, R3 e R4) em reator de plexiglass com 3,0 L de volume útil, operados com vazão de 0,75 L.h-1 e tempo de detenção hidráulica (TDH) de 4 horas. Os ensaios foram inoculados com 10% do volume útil de lodo anaeróbio de um biodigestor instalado em uma fecularia, previamente aquecido a 95 °C por 15 minutos para eliminação de microrganismos produtores de metano. O ajuste do pH da manipueira foi realizado para 6,0 somente no ensaio R1. Nos ensaios R2, R3 e R4, sem alterações do pH, os valores variaram de 3,74 a 4,47. Os reatores apresentaram média de consumo de açúcares totais superiores a 80%, com remoções de DQO de 55,26; 15,27; 46,16 e 40,42% para R1, R2, R3 e R4, respectivamente. Foi observado que a redução das vazões de biogás proporcionou maior acúmulo de biomassa no reator. Os resultados dos valores de TDH foram obtidos pelo ensaio hidrodinâmico de 3,75, 1,08, 1,83 e 2,43 para R1, R2, R3 e R4, respectivamente. Foi possível verificar que o processo de geração de hidrogênio estava associado à via metabólica de geração de ácido butírico, uma vez que o aumento deste produto da acidogênese proporcionou elevação dos valores de hidrogênio. Observou-se também que os picos de concentrações de ácido lático e propiônico no efluente ocorreram simultaneamente às reduções de produtividade e podem indicar o consumo de H2. A utilização da manipueira, sem correção de pH em R2, R3 e R4, resultou em menores produtividades de H2, possivelmente resultantes do favorecimento da solvetogênese, verificada pela elevação das produções de butanol e etanol, que coincidiram com a redução das vazões de hidrogênio. As maiores vazões molares de H2 foram observadas em R1, com valor máximo de 10,6 mmolH2.h-1. O ensaio R2 apresentou as maiores percentagens de hidrogênio no biogás (45,37%) e vazão máxima de 3,37 mmolH2.h-1, em que foram observadas as maiores concentrações de cálcio nos lotes de manipueira, utilizados naquele período. Os reatores R3 e R4 apresentaram vazões máximas de 0,99 e 1,80 mmolH2.h-1. Dessa forma, destaca-se a necessidade da correção dos valores de pH do efluente de fecularia e monitoramento dos álcoois e ácidos graxos voláteis gerados no processo.

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50

Hong, Yanjuan. "Enhanced Biological Phosphorus Removal for Liquid Dairy Manure." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/46067.

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Abstract:

Enhanced biological phosphorus removal (EBPR) has been widely used in municipal wastewater treatment, but no previous studies have examined the application of EBPR to treat dairy manure. This study was conducted to evaluate the (i) performance of pilot-scale EBPR systems treating liquid dairy manure, to balance the ratio of nitrogen to phosphorus in manure to meet crop nutrient requirements, (ii) effects of dissolved oxygen and solids retention time on the efficiency of EBPR, and (iii) effectiveness of gravity thickening for reducing the volume of harvested EBPR aerated mixed liquor. Two pilot-scale EBPR systems were used in this study. The ratio of the manure chemical oxygen demand expressed as volatile fatty acids to phosphorus used ranged from 18:1 to 45:1. The phosphorus removal efficiencies of the EBPR system were investigated at three solids retention times (4, 6 and 10 d), and three dissolved oxygen levels (3, 4 and 6 mg O2/L). The total phosphorus removal was highest (84%) at 10 d solids retention time and lowest (63%) at 4 d solids retention time. The sludge from the 6 d solids retention time tests had better sludge settling characteristics with a sludge volume index of 62 mL/g compared to 80 mL/g for the 4 d solids retention time. The EBPR system achieved 90% dissolved reactive phosphorus removal when the system was operated at 4 mg O2/L, and the ratio of nitrogen to phosphorus in effluent increased to about 5:1, which was higher than the normal ratio in dairy manure. On the other hand, phosphorus removal performance deteriorated when dissolved oxygen level was 3 mg O2/L. In the gravity thickening tests, 93-95 % total suspended solids (TSS) was removed from the settled supernatant, with 1.2 to 1.54 % total solids (TS) in the settled solids after 90 min gravity-induced thickening. The extent of phosphorus release during gravity thickening process needs to be further investigated. Master of Science

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Dissertations / Theses on the topic 'Volatile fatty acids'

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