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1
Durogbade, Samuel Adesina, Temitayo Bukola Korode, and Bamidele Honesty Akpeji. "Production of Biogas from Plantain Peels, Using Cow Dung as Substrate." British Journal of Multidisciplinary and Advanced Studies 5, no. 2 (April 20, 2024): 40–53. http://dx.doi.org/10.37745/bjmas.2022.0471.
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In a biodigester setup, the researchers investigated the production of methane gas using plantain peel and cow dung as substrates. Two buncher flasks, corks, a glass tube, and a calibrated conical flask comprised the biodigester setup. The setup involved anaerobic digestion processes, analyzing different ratios of cow dung and plantain peel to produce biogas. The main anaerobic digestion process was carried out in Buncher flask one, after which the methane gas formed was sent to Buncher flask two through a rubber tube, where the by-products such as carbon dioxide and hydrogen sulfide were absorbed from the methane gas and the refined biogas was stored in a storage tube. For this study, there were seven setups of cow dung and plantain peel in digester1, digester2, digester3, digester4, digester5, digester6, and digester7 in the ratios of 0g;100g(100%), 10g(10%): 90g(90%), 20g(20%): 80g(80%), 30g(30%): 70g(70%), 40g(40%): 60g(60%), and 50g (50%): 50g(50%), respectively. After 15 days of retention, the slurry with the highest yield is digester 1, with 574 ml/day. The obtained kinetic modeling indicates a rise in yield as the retention time increases. Furthermore, it was observed that continuous mixing boosted the biogas production yield. The results provided valuable insights into the potential for biogas production from agricultural and animal wastes through anaerobic digestion, highlighting the impact of functional groups on biogas yield.
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Yakubu, Ubaidullahi, Sani Umar Mohammed, and Mary Samuel. "TESTING THE PERFORMANCE OF TWO DIFFERENT DIGESTERS FOR BIOGAS PRODUCTION FROM HOUSEHOLD WASTE CO-DIGESTED WITH COW DUNG." FUDMA JOURNAL OF SCIENCES 8, no. 3 (June 30, 2024): 183–89. http://dx.doi.org/10.33003/fjs-2024-0803-2544.
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The research was carried out at Mechanical Engineering Department, Federal University Dutsin-Ma, Katsina State, Nigeria. Different researches of bio-digesters have been conducted for biogas production but the physico-chemical properties of wastes, constituents of biogas and volume of digesters were not considered in previous research which resulted to poor performance of digesters by producing low flame. Hence the physico-chemical properties of wastes were determined, constituents of biogas were determined and volumes of digesters were considered for this research work so as to have effective performance of the digesters. This study involved the performance evaluation of two different digesters for the production of biogas from household Wastes co-digested with cow dung to select the best digester among the two suitable for household used. Two different digesters each of 5.5 litres and 90 litres were used for testing the performance of digesters using household Wastes co-digested with cow dung in which anaerobic digestion process at both mesophilic and thermophilic temperatures were employed.After the physico-chemical properties of wastes test, analysis of biogas constituents, Ventilation test and flammability test of both digesters were conducted.The highest volume of biogas produced for Digester 1 was 115 liters/day within a period of 15days and 2537 liters/day within a period of 28days for Digester 2.The Ventilation and flammability tests were conducted of both digesters in which Digester 1 passed Ventilation test and failed flammability test.The Digester 2 passed both Ventilation and flammability tests.The research concluded that, the Digester 2 was more effective because of large volume of Digester...
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Ratner, Raisa. "INFORMATION-LIBRARY SUPPORT INNOVATIVE DEVELOPMENT OF PEDAGOGICAL SCIENCE AND EDUCATION." Infolib 23, no. 3 (September 30, 2020): 19–21. http://dx.doi.org/10.47267/2181-8207/2020/3-016.
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Information and bibliographic work of RSPL is aimed at supporting the educational activities of pedagogical staff, the promotion of pedagogical heritage. Trainings will be conducted. Presentation of innovative forms of the product is created: thematic digestes, flyers, booklets. Presents bibliographic resources in the form of a «Festival of Bibliographic Products, Resources and Services».
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Suleiman Abubakar Isa, Aisha Idris, Hafsah Musa Abubakar, and Ibrahim Yusuf. "Upscaling Biogas Production using Fruit Waste (Pawpaw, Watermelon and Banana) Co Digested with Cow Dung, and Gutter’s Sludge." International Journal of Contemporary Microbiology 10, no. 1 (May 22, 2024): 10–17. http://dx.doi.org/10.37506/1yjex237.
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Nigeria faces a significant challenge of fruit waste due to improper handling and transportation practices, leading to damage and microbial contamination, resulting in environmental pollution. These wastes can be utilized to produce biogas which is environmentally safer and cleaner. This study explores the potential of using fruit waste (Pawpaw, Watermelon, and Banana) as substrates co-digested with cow dung and gutter sludge to upscale biogas production. Physicochemical analyses of the substrates and inoculums was conducted, followed by construction of pilot biogas digesters, and then isolation of methanogenic bacteria. A combination of single and mixed fruit ratio were added into the digesters with the cow dung and gutter sludge as co-digesters. For the up scaling, a 25L digester was constructed and the best mix ratio from the pilot digesters were fed into the digesters. Isolation of methanogens was carried out to access which substrate or inoculum had greater potential in the production of biogas individually or when co-digested by the presence of methanogenic colonies after incubation. The results revealed similar physicochemical parameters among the fruit waste substrates, while cow dung and gutter sludge showed variations, particularly in carbon-nitrogen ratios. The pilot study demonstrated that the mix ratio containing all three fruits, co-digested with cow dung and gutter sludge, produced the highest methane yield (11.2%). In upscaling, a 25L digester produced gas efficiently, albeit with some depletion over time, possibly due to methanotroph activity or exposure to sunlight. Methanogenic colonies were successfully isolated from lower dilutions of gutter sludge. This study highlights the potential of fruit waste as a valuable substrate, particularly when co-digested with cow dung and gutter sludge, which can serve as an effective inoculum due to the presence of methanogens.
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Shang, Y., B. R. Johnson, and R. Sieger. "Application of the IWA Anaerobic Digestion Model (ADM1) for simulating full-scale anaerobic sewage sludge digestion." Water Science and Technology 52, no. 1-2 (July 1, 2005): 487–92. http://dx.doi.org/10.2166/wst.2005.0557.
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A steady-state implementation of the IWA Anaerobic Digestion Model No. 1 (ADM1) has been applied to the anaerobic digesters in two wastewater treatment plants. The two plants have a wastewater treatment capacity of 76,000 and 820,000 m3/day, respectively, with approximately 12 and 205 dry metric tons sludge fed to digesters per day. The main purpose of this study is to compare the ADM1 model results with full-scale anaerobic digestion performance. For both plants, the prediction of the steady-state ADM1 implementation using the suggested physico-chemical and biochemical parameter values was able to reflect the results from the actual digester operations to a reasonable degree of accuracy on all parameters. The predicted total solids (TS) and volatile solids (VS) concentration in the digested biosolids, as well as the digester volatile solids destruction (VSD), biogas production and biogas yield are within 10% of the actual digester data. This study demonstrated that the ADM1 is a powerful tool for predicting the steady-state behaviour of anaerobic digesters treating sewage sludges. In addition, it showed that the use of a whole wastewater treatment plant simulator for fractionating the digester influent into the ADM1 input parameters was successful.
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Seyedi, Saba, Kaushik Venkiteshwaran, Nicholas Benn, and Daniel Zitomer. "Inhibition during Anaerobic Co-Digestion of Aqueous Pyrolysis Liquid from Wastewater Solids and Synthetic Primary Sludge." Sustainability 12, no. 8 (April 23, 2020): 3441. http://dx.doi.org/10.3390/su12083441.
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Pyrolysis can convert wastewater solids into useful byproducts such as pyrolysis gas (py-gas), bio-oil and biochar. However, pyrolysis also yields organic-rich aqueous pyrolysis liquid (APL), which presently has no beneficial use. Autocatalytic pyrolysis can beneficially increase py-gas production and eliminate bio-oil; however, APL is still generated. This study aimed to utilize APLs derived from conventional and autocatalytic wastewater solids pyrolysis as co-digestates to produce biomethane. Results showed that digester performance was not reduced when conventional APL was co-digested. Despite having a lower phenolics concentration, catalyzed APL inhibited methane production more than conventional APL and microbial community analysis revealed a concomitant reduction in acetoclastic Methanosaeta. Long-term (over 500-day) co-digestion of conventional APL with synthetic primary sludge was performed at different APL organic loading rates (OLRs). Acclimation resulted in a doubling of biomass tolerance to APL toxicity. However, at OLRs higher than 0.10 gCOD/Lr-d (COD = chemical oxygen demand, Lr = liter of reactor), methane production was inhibited. In conclusion, conventional APL COD was stoichiometrically converted to methane in quasi steady state, semi-continuous fed co-digesters at OLR ≤ 0.10 gCOD/Lr-d. Undetected organic compounds in the catalyzed APL ostensibly inhibited anaerobic digestion. Strategies such as use of specific acclimated inoculum, addition of biochar to the digester and pretreatment to remove toxicants may improve future APL digestion efforts.
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Taskaev, M. V., L. A. Garifyanova, and M. V. Svalova. "Analysis of the Methane Tanks Structures for the Sludge Treatment from Sewage Treatment Plants." Intellekt. Sist. Proizv. 20, no. 1 (April 2, 2022): 96–105. http://dx.doi.org/10.22213/2410-9304-2022-1-96-105.
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The paper presents analysis of digester designs, considers the advantages and disadvantages of biogas plants. Experimental data of technological process of anaerobic digestion in biogas plant are given, relation between temperature and time of raw sludge digestion is shown. The methodology of research of technological processes occurring in digesters at the experimental biogas plant AN-BR-3 is given. The principle of digesters operation is described. The most effective thermophilic mode of digestion is revealed. The relation between temperature and time during digestion in biogas plant has been established based on the results of experimental studies. Principle diagrams of digester designs, with dome-shaped overlapping, with floating overlapping, open-ended are presented. The operating conditions of digesters, depending on which the most effective technological scheme of digestion is being chosen, are given. The technology of methane digestion is presented. The analysis of ways of mixing the digested mass is given in the work. Stages of experimental studies of the technological process of anaerobic digestion depending on the temperature regime are presented. Two basic technological schemes of digestion are presented: one-stage and two-stage. The prospects of application of digesters for treatment of sewage sludge from wastewater treatment plants are shown.
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Phuong, Nguyen Le. "STUDY ON CO-FERMENTATION OF COW DUNG AND GIANT DIRT IN SEMI-CONTINUOUS ANAEROBIC DIGESTER." Vietnam Journal of Science and Technology 54, no. 2A (March 19, 2018): 287. http://dx.doi.org/10.15625/2525-2518/54/2a/11943.
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Study on co-fermentation of cow dung (CD) and giant dirt (GD - Pistia stratiotes L.) in semi-continuous anaerobic digester aims to test biogas quantity and quality by time. Three mixing rates counted based on ODM of each material were chosen: 100 %CD, 50 %CD + 50 %GD, and 100 %GD. The experiments were set up in laboratory conditions with two types of digesters: one-stage digesters and two-stage digesters (triplicate for each treatment). After 80 days, the biogas produced from the one-stage digesters was not significantly different to the two-stage digesters with similar input material. The highest production of biogas came from digesters of 100 %GD - 235.8 L for the one-stage and 240.3 L for the two-stages. The medium production came from digesters of 50 %CD + 50 %GD - 127.8 L for the one-stage and 118.4 L for the two-stages. After one month, the percentage of CH4 was high enough for burning and almost giant dirt was digested that limited of a blockage inside the digesters. The results showed that co-fermentation of GD and CD is an alternative for livestock raising households to produce biogas for energy purpose.
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Zikakis, D., J. Chauzy, I. Droubogianni, and A. Georgakopoulos. "Why applying THP on waste activated sludge makes sense: Psyttalia – Athens case study." Water Practice and Technology 14, no. 4 (November 14, 2019): 921–30. http://dx.doi.org/10.2166/wpt.2019.078.
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Abstract In order to improve the energy footprint of Psyttalia wastewater treatment plant (WWTP) in Athens, the application of a thermal hydrolysis process (THP) was preferred to the option of constructing additional digesters. Since August 2015, approximately half of the generated waste activated sludge (WAS) has been treated by a Cambi B6-4 system, while the thickened primary sludge (PS) is by-passing the THP and is mixed with the hydrolysed WAS before entering the 4 digesters. The 4 other conventional digesters have treated the remaining sludge. The dewaterability of the mixed digested sludge has significantly been improved from 22% dry solids (DS) before THP installation, up to 31% DS after THP installation. This is providing substantial reduction of energy use and cost savings at the sludge drying plant of Psyttalia. In addition, biogas generation and digester efficiency (VSR) have been increased.
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Engeli, H., W. Edelmann, J. Fuchs, and K. Rottermann. "Survival of Plant Pathogens and Weed Seeds during Anaerobic Digestion." Water Science and Technology 27, no. 2 (January 1, 1993): 69–76. http://dx.doi.org/10.2166/wst.1993.0079.
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The survival of Plasmodiophora brassicae was studied at digestion temperatures of 35 °C and 55 °C in laboratory batch digesters within one and two weeks, respectively. The study showed that digestion at 55 °C almost completely reduced the ability of infecting bait plants. The seeds of Rumex obtusifolius and Lycopersicon lycopersicum (tomatoes) were completely destroyed at 55 °C and a digestion time of 14 days, in laboratory batch digesters. The experiments carried out in a two stage pilot plant (Leach-Bed Solid Phase batch Digester for hydrolysis and a pulsating dynamic anaerobic filter for methanogenesis) showed that hydrolytic conditions are mainly responsible for the killing of weed seeds. Some additional data on the qualities of different digested substrates are presented.
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Navaneethan, N., P. Topczewski, S. Royer, and D. Zitomer. "Blending anaerobic co-digestates: synergism and economics." Water Science and Technology 63, no. 12 (June 1, 2011): 2916–22. http://dx.doi.org/10.2166/wst.2011.557.
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Co-digestion is the process in which wastes from various sources are treated together. Therefore, more organic carbon is added to make efficient use of existing digesters. The objectives of this study were to compare potential co-digestates, determine synergistic and antagonistic co-digestion outcomes and estimate economic benefits for preliminary screening. Over 80 wastes were identified from 54 facilities within 160 km of an existing municipal digester. Synergistic, antagonistic and neutral co-digestion outcomes were observed for the various wastes. A simple economic comparison resulted in the greatest potential benefits for four co-digestates: yeast flavorings production waste, meat production dissolved air flotation float, acid whey from cheese production and thin stillage from corn ethanol production. Performance was investigated using bench-scale digesters receiving primary sludge with and without co-digestates. Methane production rates were 105 and 66% higher when co-digestates were present, but were anticipated to increase only 57 and 23% due to the additional chemical oxygen demand. Therefore, significant synergistic outcomes were observed during co-digestion. Co-digestion of the most promising wastes with primary sludge in full scale was estimated to generate enough electricity to power more than 2,500 houses.
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Tanguay-Rioux, Fabrice, Laurent Spreutels, Caroline Roy, and Jean-Claude Frigon. "Assessment of the Feasibility of Converting the Liquid Fraction Separated from Fruit and Vegetable Waste in a UASB Digester." Bioengineering 11, no. 1 (December 21, 2023): 6. http://dx.doi.org/10.3390/bioengineering11010006.
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Anaerobic digestion of food waste still faces important challenges despite its world-wide application. An important fraction of food waste is composed of organic material having a low hydrolysis rate and which is often not degraded in digesters. The addition of this less hydrolysable fraction into anaerobic digesters requires a longer hydraulic residence time, and therefore leads to oversizing of the digesters. To overcome this problem, the conversion of the highly biodegradable liquid fraction from fruit and vegetable waste in a up-flow anaerobic sludge blanket (UASB) digester is proposed and demonstrated. The more easily biodegradable fraction of the waste is concentrated in the liquid phase using a 2-stage screw press separation. Then, this liquid fraction is digested in a 3.5 L UASB digester at a high organic loading rate. A good and stable performance was observed up to an organic loading rate (OLR) of 12 g COD/(Lrx.d), with a specific methane production of 2.6 L CH4/(Lrx.d) and a degradation of 85% of the initial total COD. Compared to the conversion of the same initial waste with a continuously stirred tank reactor (CSTR), this new treatment strategy leads to 10% lower COD degradation, but can produce the same amount of methane with a digester that is twice as small. The scale-up of this process could contribute to reduced costs related to the anaerobic digestion of food waste, while reducing management efforts associated with digestate handling and increasing process stability at high organic loading rates.
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Charles, W., R. Cord-Ruwisch, G. Ho, M. Costa, and P. Spencer. "Solutions to a combined problem of excessive hydrogen sulfide in biogas and struvite scaling." Water Science and Technology 53, no. 6 (March 1, 2006): 203–11. http://dx.doi.org/10.2166/wst.2006.198.
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The Woodman Point Wastewater Treatment Plant (WWTP) in Western Australia has experienced two separate problems causing avoidable maintenance costs: the build-up of massive struvite (MgNH4PO4· 6H2O) scaling downstream of the anaerobic digester and the formation of hydrogen sulfide (H2S) levels in the digester gas to levels that compromised gas engine operation and caused high operating costs on the gas scrubber. As both problems hang together with a chemical imbalance in the anaerobic digester, we decided to investigate whether both problems could be (feasibly and economically) addressed by a common solution (such as dosing of iron solutions to precipitate both sulfide and phosphate), or by using separate approaches. Laboratory results showed that, the hydrogen sulfide emission in digesters could be effectively and economically controlled by the addition of iron dosing. Slightly higher than the theoretical value of 1.5 mol of FeCl3 was required to precipitate 1 mol of dissolved sulfide inside the digester. Due to the high concentration of PO43− in the digested sludge liquor, significantly higher iron is required for struvite precipitation. Iron dosing did not appear an economic solution for struvite control via iron phosphate formation. By taking advantage of the natural tendency of struvite formation in the digester liquid, it is possible to reduce the risk of struvite precipitation in and around the sludge-dewatering centrifuge by increasing the pH to precipitate struvite out before passing through the centrifuge. However, as the Mg2+ /PO43− molar ratio in digested sludge was low, by increasing the pH alone (using NaOH) the precipitation of PO43− was limited by the amount of cations (Ca2+ and Mg2+ ) available in the sludge. Although this would reduce struvite precipitation in the centrifuge, it could not significantly reduce PO43− recycling back to the plant. For long-term operation, maximum PO43− reduction should be the ultimate aim to minimise PO43− accumulation in the plant. Magnesium hydroxide liquid (MHL) was found to be the most cost-effective chemical to achieve this goal. It enhanced struvite precipitation from both, digested sludge and centrate to the point where more than 95% PO43− reduction in the digested sludge was achieved.
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Tinajero, A., and A. Noyola. "Increasing microbial activity in thermophilic anaerobic digestion of physicochemical sludge." Water Science and Technology 54, no. 2 (July 1, 2006): 245–51. http://dx.doi.org/10.2166/wst.2006.512.
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Two thermophilic lab-scale reactors of 5 L were operated on a daily fed basis. Digester T1 received raw sludge (control) and digester T2 was fed with raw sludge plus metallic micronutrients and a bacilli additive. Raw sludge was obtained from a municipal chemically enhanced primary treatment plant. The effect of additives was clear on methane production, since on day 50, digester T2 produced 900 ml more methane than T1, an increase of 64%. On day 80, T2 reached twice the production of biogas of T1. Volatile solid removal (% VSR) in T2 increased to 29%; while T1 achieved only 15%. Acetic acid concentration in T2 diminished to 100 mg/L, which related to the higher biogas production. Based on the Mexican biosolids standard, the digested sludge reached Class A biosolids, in both digesters: fecal coliforms were reduced to less than 1000 MPN/gTS; Salmonella spp was totally eliminated and helminth egg counts were lower than one viable egg per gram of total solids.
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Villegas, J. D., H. Fruteau de Laclos, J. Dovat, Y. Membrez, and C. Holliger. "Nitrogen removal from digested manure in a simple one-stage process." Water Science and Technology 63, no. 9 (May 1, 2011): 1991–96. http://dx.doi.org/10.2166/wst.2011.430.
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A process based on partial nitrification and recirculation into the anaerobic digester was studied to remove nitrogen from digested manure and thus reduce enhanced gaseous ammonia emissions due to on-farm biogas production. An anaerobic reactor representing an anaerobic manure digester was fed with a nitrite solution and digested manure liquor. Nitrite was efficiently removed from the influent and ammonium formation was observed first. Ammonium was subsequently eliminated up to a maximum of 90% of the influent concentration, indicating anaerobic ammonium oxidation activity. This activity, however, decreased again and was lost at the end of the 4-month operation period. In a 1.5 L aerobic CSTR that was fed with digested manure liquor, ammonium was efficiently removed from the influent. Nitrite and nitrate formation was observed but mass balances indicated significant N-removal. Accumulation of suspended solids was observed at the end of the experiment suggesting presence of oxygen-free environments. In a second test in a 15 L CSTR where suspended solids sedimentation could be avoided, low N-removal rates were observed in the absence of biofilm carrier elements whereas high N-removal rates were achieved in their presence. A simple one-stage process based on immobilized biomass could therefore be installed downstream of agricultural anaerobic digesters in order to mitigate undesirable gaseous ammonia emissions.
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Cecchi, F., P. Pavan, and J. Mata-Alvarez. "Fast Digester Start-Up under Mesophilic Conditions Using Thermophilic Inoculum." Water Science and Technology 25, no. 4-5 (February 1, 1992): 391–98. http://dx.doi.org/10.2166/wst.1992.0518.
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The paper deals with fast procedures adopted for starting-up anaerobic digesters treating biological wastes. In particular, results related to the behaviour of a digester treating sewage sludge with a fast start-up (in 22 days) and using a thermophilic inoculum are presented and compared with those related to a passage from mesophilic to thermophilic temperatures (from 37 to 55°C, in 31 days) and to a direct re-start-up under thermophilic conditions (27 days). In the latter cases, the organic fraction of municipal solid wastes was digested. Main findings concern: the identification of two retention times as the necessary period for reaching the first steady-state condition; the usefulness of performing a real time process monitoring the observation that thermophilic inoculum allows better digester performances in the first start-up period, a finding however, that requires more experimental work.
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Olsson, J., S. Schwede, E. Nehrenheim, and E. Thorin. "Microalgae as biological treatment for municipal wastewater – effects on the sludge handling in a treatment plant." Water Science and Technology 78, no. 3 (July 24, 2018): 644–54. http://dx.doi.org/10.2166/wst.2018.334.
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Abstract A mix of microalgae and bacteria was cultivated on pre-sedimented municipal wastewater in a continuous operated microalgae-activated sludge process. The excess material from the process was co-digested with primary sludge in mesophilic and thermophilic conditions in semi-continuous mode (5 L digesters). Two reference digesters (5 L digesters) fed with waste-activated sludge (WAS) and primary sludge were operated in parallel. The methane yield was slightly reduced (≈10%) when the microalgal-bacterial substrate was used in place of the WAS in thermophilic conditions, but remained approximately similar in mesophilic conditions. The uptake of heavy metals was higher with the microalgal-bacterial substrate in comparison to the WAS, which resulted in higher levels of heavy metals in the digestates. The addition of microalgal-bacterial substrate enhanced the dewaterability in thermophilic conditions. Finally, excess heat can be recovered in both mesophilic and thermophilic conditions.
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Mohamed Ali, Amina, Md Zahangir Alam, Fatouma Mohamed Abdoul-latif, Mohammed Saedi Jami, Ibrahim Gamiye Bouh, Ibrahim Adebayo Bello, and Tarik Ainane. "Production of Biogas from Food Waste Using the Anaerobic Digestion Process with Biofilm-Based Pretreatment." Processes 11, no. 3 (February 21, 2023): 655. http://dx.doi.org/10.3390/pr11030655.
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The production of biogas from food waste is a good approach to the minimization of food waste and increase in the production of renewable energy. However, the use of food waste as a feedstock for biogas production currently poses a difficulty due to an ineffective hydrolysis process, which is a pretreatment procedure and the initial step of the biogas conversion process. This restriction results from the food waste polymers’ solubilization and breakdown. This has an impact on the volume of biogas produced during the methanogenesis stage. It is essential to increase the biodegradation of organic compounds (OC) during the hydrolysis process to increase biogas generation. This study focuses on the enhancement of biogas production by the anaerobic digestion (AD) of food waste (FW). FW was hydrolyzed by the immobilized biofilm and digested anaerobically in a semi-continuous digester. Four different digesters including the control were prepared. The control digester composed of no hydrolyzed food waste had no immobilized biofilm while the other three digesters had immobilized biofilm-hydrolyzed food waste with inoculum concentrations of 10%, 30%, and 50%. The results showed that the 50% digester had the highest biogas yield of about 2000 mL/500 mL. The 10%, 30%, and control digesters had a biogas yield of 1523 mL, 753 mL, and 502 mL respectively. Thus, the analysis of total volatile solid (TVS) reduction in the digesters with 10%, 30%, and 50% inoculum and the control have increased to 43.4% for the digesters with 30% and 10%, 60% for the digester with 50% inoculum, and only 29% for the control. Total chemical demand (TCOD) removal increased to 29%, 33%, 43%, and 56% for the control, and 10%, 30%, and 50%, respectively for the inoculum-to-feed ratio. From these results, the 50% inoculum-to-feed ratio has shown the highest biogas production and highest degradation based on TVS reduction and TCOD reduction. Based on this study, the biofilm pretreatment method can be considered a promising method for the enhancement of biogas volume and biodegradation. Biogas production was high (2000 mL) for hydraulic retention time (HRT = 20) days but the HRT = 15 days was also able to produce a significant amount (1400 mL) of biogas and the 50% inoculum-to-feed ratio has shown the highest volume of biogas production.
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Shrestha, Sagar, and Sunil Prasad Lohani. "CFD analysis for mixing performance of different types of household biodigesters." Clean Energy 6, no. 2 (April 1, 2022): 1090–99. http://dx.doi.org/10.1093/ce/zkac009.
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Abstract Household biodigesters are self-mixing anaerobic digesters used mostly in rural areas of developing countries as a reliable source of clean cooking energy. For an efficient anaerobic digestion process, the mixing of slurry inside the digester is regarded as one of the most important parameters. In this study, the mixing of slurry in three different designs of household digesters, namely the fixed-dome digester (GGC 2047 model), plug-flow digester and prefabricated plastic digester, are investigated and compared using computational fluid dynamics. A 3D transient simulation is performed using a multiphase volume of fluid (VOF) model in Ansys® Fluent release 16.0. The rheological properties of the feedstock are considered identical for all three digesters. The volume of the plug-flow and prefabricated plastic digesters is designed to be 1 m3 while the volume of the GGC 2047 digester was 6 m3 as the standard size of the household digester. The regions inside the digester where the velocity of slurry is <0.02 m/s are regarded as dead zones and the obtained results were analysed and compared using velocity patterns and dead-zone formation. It is found that the prefabricated plastic digester model has a relatively higher percentage of dead volume (74.6%) and the plug-flow digester has the lowest percentage (54%) of dead volume among digesters that were compared in this study. The study will serve as the basis for designers and researchers to improve the design of household digesters for better mixing performances.
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N. Sharma, U. G. Phutela, S. K. Khattra, and I. Singh. "Valorization of spent mushroom substrate (SMS) along with rice straw as feedstock for efficient bio gasification." Ecology, Environment and Conservation 29, suppl (2023): 332–39. http://dx.doi.org/10.53550/eec.2023.v29i06s.050.
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Wastes generated after mushroom harvesting are known as spent mushroom substrate (SMS) which causes contamination of the environment. Anaerobic digestion is an economical and viable technology used for the management of several types of agricultural wastes, thus generating syngas that has many thermal applications. The current manuscript reports the potential of SMS for anaerobic digestion in five different combinations with rice straw, cattle dung, and bio-digested slurry. The kinetics of the biogasification process occurring in digesters was analyzed by modified Gompertz model. Results showed that maximum biogas (3,12,664 ml) was produced in digester C containing SMS, rice straw, cattle dung, and bio-digested slurry in the ratio of 8:2:1:1 as compared to control (48,968 ml) consisting of only SMS and water in the ratio of 8:2. Evaluation of feedstock for proximate and chemical composition recorded a notable reduction in total solids (TS), volatile solids (VS), cellulose, hemicellulose, lignin content as compared to control. On the other hand, ash content showed a significant increase after anaerobic digestion. Modified Gompertz equation revealed that maximum biogas production potential (P) of 6,150.50 mLg-1 VS with a biogas production rate (Rm) of 134 mLg-1d -1 and lag phase () of 12.80 days was observed in digester C as compared to the control digester A (P= 12.24 mLg-1 VS; Rm = 8.56 mLg-1d -1; =8.80 days). The study demonstrated that the codigesting SMS with rice straw can be successfully implicated for producing biogas as an energy source rather making dumped at the village site for causing pollution.
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Pagilla, Krishna R., Kent C. Craney, and Wendell H. Kido. "Causes and effects of foaming in anaerobic sludge digesters." Water Science and Technology 36, no. 6-7 (September 1, 1997): 463–70. http://dx.doi.org/10.2166/wst.1997.0624.
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Full scale anaerobic digesters treating mixed sludge containing primary sludge and thickened waste activated sludge were investigated for causes and effects of foaming. Sludge samples were collected from different depths of two full scale digesters, one gas-mixed, and the other mechanically-mixed, to determine the extent of foaming and its effects on anaerobic digestion; both digesters were fed the same feed sludge (3.4% TS) and at the same feed rate (about 2.2 kg TS/m3.day). The average depth of the surface foam layer in the gas-mixed and mechanically-mixed digester were 2.4 and 1.3 m respectively. Higher total solids concentrations were found at the surface (about 5% TS) than those found at the bottom (about 2% TS) in both gas-mixed and mechanically-mixed digesters, indicating an inverse total solids profile. Presence of excessive levels of Nocardia filaments (>106 number/g VSS) in the activated sludge caused thicker foam layer at the surface, and this effect was more pronounced in the gas-mixed digester than in the mechanically-mixed digester. Gas-mixed digester (0.74 m3/kg VS destroyed) produced less sludge gas than the mechanically-mixed digester (0.93 m3/kg VS destroyed), however, gas-mixed digester (62% VS reduction) destroyed more volatile solids than the mechanically-mixed digester (54% VS reduction). These results indicate that gas-mixed digesters are more prone to foaming than mechanically-mixed digesters, and that the foaming can increase when excessive levels of Nocardia filaments are present in the feed sludge causing decreased digester performance.
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Pradip B. Acharya, Pradip, and Prateek Shilpkar. "Solanum tuberosum Supplementation for Biogas Production." Current World Environment 10, no. 1 (April 30, 2015): 285–87. http://dx.doi.org/10.12944/cwe.10.1.35.
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Production of biogas using animal dung is well documented. Nutritional supplement enhances microbial activity and ultimately results in increase biogas production. Solanum tuberosum (potato) is a vegetable crop grown in most parts of world. It is a rich source of carbohydrate starch and many minerals. Present experiment was conducted in 5L capacity glass digester bottles filled with mixture of buffalo dung and water at 5.3% total solids. A total of six sets were prepared, three as control and three as test. Control sets were fed daily with buffalo dung water mixture throughout the period of experimentation, i.e. 80 days, whereas in test, from 51st day onward digesters were filled with mixture of dung and boiled potato with water. Feed was added daily in the amount of 120mL upto 80 days from beginning. On first day 12 mL fresh digested biogas slurry from running biogas plant was also added in all the digesters as inoculum. From 41th day onward biogas production was recorded by water displacement method and compared. Results reveal that in test digesters addition of potato shows an immediate and long lasting effect and increases biogas production between 90.48 and 192.86% higher than control sets.
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Nazo Edith, Kpata-Konan, Kouame Francis, and NGBADJO Tanon Virginie. "OPTIMIZATION OF CASSAVA EFFLUENT BIOMETHANIZATION WITH ASH AS COSUBSTRATE." International Journal of Advanced Research 11, no. 09 (September 30, 2023): 1190–97. http://dx.doi.org/10.21474/ijar01/17634.
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The main objective of this study is to determine the optimal conditions for anaerobic biodigestion of cassava effluents with the ash of cassava peels as co-substrate. To do this, three (03) digesters were used in which were put effluent + ash for digester 1, effluent + ash + cow dung for digester 2 and effluent + ash + urine for digester 3. The physico-chemical parameters (temperature, pH), biochemical parameters (COD and TKN) and the volume of biogas produced were quantified. In each of the reaction media a decrease in values was observed in pH (digester 1: 7.15 to 6.92 digester 2: 7.20 to 5.38 digester 3: 7.00 to 5.28), COD (digester 1: 1.66g/l to 1.16g/l digester 2: 1.81g/l to 1.44g/l digester 3: 1.46g/l to 0.99g/l) and NTK (digester 1: 0.27 g/l to 0.24 g/l digester 2: 0.29 g/l to 0.22 g/l digester 3: 0.25 g/l 0.16 g/l). ¨For the temperature of the media, the recorded values are in the range of mesophilic fermentation (digester 1: 26.66°C, digester 2: 27.97°C and digester 3: 27°C). Regarding gas production, the digesters produced gas from day 1 with 37.463 m3, 37.463 m3 and 69.272 m3 respectively. A significant improvement in the biogas production rate was observed in all digesters. Thus, the ash could be used as a replacement for human urine for pH adjustment of cassava effluents.
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Tseng, D. W. S., and M. A. Connor. "The effect of disc submergence level on the performance of a laboratory-scale anaerobic rotating biological contactor: implications for digester design and modelling." Water Science and Technology 30, no. 12 (December 1, 1994): 357–65. http://dx.doi.org/10.2166/wst.1994.0635.
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A hypothesis was advanced that an anaerobic rotating biological contactor (AnRBC) digester, if operated with its discs half rather than fully submerged, should show an enhanced capability to withstand shock loads. Laboratory-scale AnRBC digesters were constructed and their performance under 50% and 100% disc submergence conditions compared. In all cases, under otherwise comparable conditions the performance in the 50% disc submergence mode was better. From measurements, including biogas hydrogen concentration, pH and propionic acid content of the digester liquid, it was concluded that it was the markedly better hydrogen stripping capability of the digester operated with discs only half submerged that accounted for its superior performance. Implications for design and modelling of digesters are discussed. It is concluded that current models of anaerobic digester systems need to reflect more accurately the actual hydrodynamic conditions in digesters if good predictions of digester performance under dynamic conditions are to be realised.
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Serhij, Kravtsov, Vlasenko Serhii, Rozhnov Oleh, and Iryna Malinovska. "Legal procedure in roman law and its reflection in modern civil procedure." Cuestiones Políticas 39, no. 71 (December 25, 2021): 921–41. http://dx.doi.org/10.46398/cuestpol.3971.56.
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Tremendous efforts of legislators are directed towards the development of an ideal judicial system and procedure of administering justice. However, current trends of judiciary reformation are easier to comprehend and accept if we turn to the origins of legal protection of human rights which, undoubtedly, go back to the Roman law. Methodology: From this point we use comparing methods for analizing the legislative provisions; the structural method and historical method was used for the background of Legal procedure in roman law. Results and conclusions: In this article we will outline the main stages of formation of legal protection of human rights in Roman law and characterize types of these processes – namely legis actiones, formulary procedure and cognitio. By analyzing the original sources that have survived to our times, namely the Law of Twelve Tables, Gaius`s Institutions and Justinian`s Digestes, we will examine what peculiarities of consideration and resolution of cases each of these stages demonstrated; how the traditional views on the behavior of the parties and the court in the process were established; which main requirements were applied to justice in civil matters in Roman law. The course of the work the following methods were used: essential, comparative, general historical.
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Vanyushina, A. Ya, A. M. Agarev, S. I. Moyzhes, Yu A. Nikolaev, M. V. Kevbrina, and M. N. Kozlov. "Comparison of different thickening methods for active biomass recycle for anaerobic digestion of wastewater sludge." Water Science and Technology 66, no. 8 (October 1, 2012): 1787–93. http://dx.doi.org/10.2166/wst.2012.405.
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The effect of returning solids to the digester, after one of three thickening processes, on volatile solids reduction (VSR) and gas production was investigated. Three different thickening methods were compared: centrifugation, flotation and gravitational sedimentation. The amount and activity of retained biomass in thickened recycled sludge affected the efficiency of digestion. Semi-continuous laboratory digesters were used to study the influence of thickening processes on thermophilic sludge digestion efficiency. Centrifugation was the most effective method used and caused an increase of VSR from 43% (control) up to 70% and gas generation from 0.40 to 0.44 L g−1 VS. Flotation and gravitational sedimentation ways of thickening appeared to be less effective if compared with centrifugation. These methods increased VSR only by up to 65 and 51%, respectively and showed no significant increase of gas production. The dewatering capacity of digested sludge, as measured by its specific resistance to filtration, was essentially better for the sludge digested in the reactors with centrifugated and settled recycle. The VS concentration of recycle (g L−1), as reflecting the amount of retained biomass, appeared to be one of the most important factors influencing the efficiency of sludge digestion in the recycling technology.
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Feitz, A. J., J. Guan, and T. D. Waite. "Size and structure effects on centrifugal dewatering of digested sewage sludge." Water Science and Technology 44, no. 2-3 (July 1, 2001): 427–35. http://dx.doi.org/10.2166/wst.2001.0798.
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The application of light scattering over small angles for the determination of digested sludge floc size and structure and its relationship with dewaterability is investigated. It appears that improved dewatering corresponds with lower floc fractal dimension (a more open structure) and a smaller proportion of fine particles. The initial increase in fractal dimension with increasing polymer dose for the digested sludge is most likely due to more efficient aggregation of the finer particles and the resulting formation of denser particle aggregates. A large colloidal fractal of the digested sludge (< 10 μm) appears to be less negative than the bulk digested sludge. This suggests that the fine particles will react differently and possibly less aggressively to the cationic polymer than the larger and more negative particles. The higher negative charge associated with the larger particles might be related to greater levels of highly negatively charged extracellular polysaccharides (EPS) adsorbed to the flocs or could result from the association of FeS with the finer fraction. The appearance of much greater levels of fine particles after digestion suggests that the flocs have undergone disintegration. Whether this is due to reduced biological efficiency within the digestor or iron reduction under the anaerobic conditions is not known for certain, although no indication of prolonged stress in the digesters could be found from plant performance data.
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Mao, T., and K. Y. Show. "Performance of high-rate sludge digesters fed with sonicated sludge." Water Science and Technology 54, no. 9 (November 1, 2006): 27–33. http://dx.doi.org/10.2166/wst.2006.798.
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A major limitation of anaerobic sludge digestion is the long hydraulic retention time (HRT) required for satisfactory stabilization which results in large digester size. This study explored a possibility of operating digesters at shortened HRTs by sonication pretreatment of secondary sludges. Four identical digesters designated D1, D2, D3 and D4 were fed with untreated and sludge sonicated at densities of 0.18 W/ml, 0.33 W/ml and 0.52 W/ml, respectively. All digesters were operated at three HRTs of 8-day, 4-day and 2-day. Comparing with the control digester (D1), total solids removal efficiencies improved by 12–19%, 17–36% and 20–39% in digesters D2, D3 and D4, respectively. The volatile solids removal was also increased by 11–21%, 17–33% and 19–36% in the respective digesters. The improved solids degradation corresponded with increase in biogas production by 1.4–2.5, 1.9–3.0 and 1.6–3.1 times, respectively. Increase in methane composition by 2–17% was also noted in all digesters fed with sonicated sludge. An analysis indicated that sonication pretreatment could enhance degradation of carbon, nitrogen and sulfur substances in the digestion. The study suggested that sonication of sludge is a possible pretreatment to shorten the digester operating HRT with improvement in solids degradation, biogas production and methane content. It can be deduced that to maintain a consistent solids loading at a desire performance, sludge digester with smaller size can be designed.
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Oladeji, Amoo Afeez, Adeleye Olarewaju Adeniyi, Haruna Adamu, Amoo Florence Kemi, and Ahmed Sabo. "Isolation and Identification of Some Bacteria Associated with Biogas Production from Food Waste and Rumen Content." Indonesian Journal of Innovation and Applied Sciences (IJIAS) 4, no. 1 (February 29, 2024): 1–11. http://dx.doi.org/10.47540/ijias.v4i1.860.
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The goal of this study was to investigate the bacterial community associated with biogas production from food waste and rumen content. Anaerobic mono-digestion and co-digestion were performed using mixture design within Design Expert, resulting in 100 experimental runs. Parameters such as food waste and rumen content, water content, temperature, pH, number of digester agitation per day and retention time were varied during the anaerobic digestion processes. Classical microbiological techniques were used to isolate and identify strict anaerobic and facultative anaerobic bacteria from the food waste and rumen content before and after anaerobic digestion. Sixteen bacterial species belonging to 12 different generae were isolated and identified from the food waste, rumen content and composite digestates obtained from the 100 bio-digesters. These generae included Acetobacterium, Bacteroides, Clostridium, Enterobacter, Escherichia, Lactobacillus, Pseudomonas, Ruminococcus, Staphylococcus, Streptococcus, Syntrophomonas and Syntrophobacter. With the exception of Escherichia coli and Pseudomonas sp., all other bacterial species identified in the substrates were also found in samples of the composite digestates, suggesting that they may have played important roles in the anaerobic digestion process inside the 100 bio-digesters. Overall, this study provides valuable insights into the microbial community structure and function during biogas production from food waste and rumen content. The results could contribute to the development of more efficient and sustainable biogas production processes.
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Naphtali, James, Alexander W. Y. Chan, Faizan Saleem, Enze Li, Jacob Devries, and Herb E. Schellhorn. "Comparative Metagenomics of Anaerobic Digester Communities Reveals Sulfidogenic and Methanogenic Microbial Subgroups in Conventional and Plug Flow Residential Septic Tank Systems." Processes 10, no. 3 (February 22, 2022): 436. http://dx.doi.org/10.3390/pr10030436.
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On-site wastewater treatment systems (OWTS) are primarily monitored using physiochemical factors, including chemical oxygen demand (COD) and residual total suspended solids (TSS), which are indirect measures of the microbial action during the anaerobic digestion process. Changes in anaerobic digester microbial communities can alter the digester performance, but this information cannot be directly obtained from traditional physicochemical indicators. The potential of metagenomic DNA sequencing as a tool for taxonomic and functional profiling of microbial communities was examined in both common conventional and plug flow-type anaerobic digesters (single-pass and recirculating). Compared to conventional digesters, plug flow-type digesters had higher relative levels of sulfate-reducing bacteria (Desulfovibrio spp.) and hydrogenotrophic methanogens (Methanospirillum spp.). In contrast, recirculating anaerobic digesters were enriched with denitrifier bacteria and hydrogenotrophic methanogens, and both were significantly correlated with physicochemical factors such as COD and TSS. Stratification of microbial communities was observed along the digester treatment process according to hydrolytic, acidogenic, acetogenic, and methanogenic subgroups. These results indicate that the high-throughput DNA sequencing may be useful as a monitoring tool to characterize the changes in bacterial communities and the functional profile due to differences in digester design in on-site systems.
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Marseglia, Angela, Luca Dellafiora, Barbara Prandi, Veronica Lolli, Stefano Sforza, Pietro Cozzini, Tullia Tedeschi, Gianni Galaverna, and Augusta Caligiani. "Simulated Gastrointestinal Digestion of Cocoa: Detection of Resistant Peptides and In Silico/In Vitro Prediction of Their Ace Inhibitory Activity." Nutrients 11, no. 5 (April 30, 2019): 985. http://dx.doi.org/10.3390/nu11050985.
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In this study we investigated the oligopeptide pattern in fermented cocoa beans and derived products after simulated gastrointestinal digestion. Peptides in digested cocoa samples were identified based on the mass fragmentation and on the software analysis of vicilin and 21 KDa cocoa seed protein sequences, the most abundant cocoa proteins. Quantification was carried out by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS) using an internal standard. Sixty five peptides were identified in the digested samples, including three pyroglutamyl derivatives. The in vitro angiotensin-converting enzyme (ACE)-inhibitory activity of cocoa digests were tested, demonstrating a high inhibition activity, especially for digestates of cocoa beans. The peptides identified were screened for their potential ACE inhibitory activity through an in silico approach, and about 20 di-, three- and tetra-peptides actually present in our samples were predicted as active. Two of the potentially active peptides were chemically synthesized and then assessed for their inhibitory activity by using the ACE in vitro assay. These peptides demonstrated an ACE inhibitory activity, however, that was too weak to explain alone the high activity of cocoa digestates, suggesting a synergic effect of all cocoa peptides. As a whole, results showed that an average chocolate portion (30 g) ensures an amount of peptides after digestion that, assuming complete absorption, could reach almost a complete inhibition of ACE.
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E., Ibeaja, Adamma Chinyere, Nwaogazie, Ify L., and Udeh, N. U. "Influence of Potash on Biogas Production from Cow Dung and Food Waste." Journal of Engineering Research and Reports 24, no. 7 (March 10, 2023): 43–52. http://dx.doi.org/10.9734/jerr/2023/v24i7830.
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This study investigated the production of biogas from food waste co-digested with potash and cow dung as inoculant. The aim of this study was to determine the amount of biogas generated from the waste substrate. Experimental research design was used and it was carried out at Uturu, Abia State, Nigeria. 4% to 12% concentrations of the substrate were mixed and fed into anaerobic digesters labeled B1 to B9 for 90days. Result of ultimate analysis showed oxygen (41.33%,14.06%), nitrogen (3.23%,1.48%), carbon (36.50%,29.67%) and PH value(6.25, 8.47) for food waste and cow dung respectively. The quantity of biogas generated in the different digesters (B1-B9) was 1341.2, 1668, 1784.5, 1945.2, 1941.7, 2159.2, 2328.1 and 2428.5m3/day respectively. Analysis of Covariance (ANCOVA) used to model the biogas production volume showed that there was significant contributions in predicting the volume of biogas produced with F (9,611) = 2684.28 and p-value <0.0001. The effect of potash on biogas production revealed that there was an increase in the quantity of gas generated by the substrates with increase in quantity of potash added. Digester B1 with the lowest quantity of potash, generated 1341.2m3/day of biogas while Digester B9 with the highest quantity of potash, generated 2428.5m3/day of biogas in 90days. The flame test showed that the biogas burned with a blue flame. The findings revealed that biogas can be generated from co-digestion of food waste, potash and cow dung. Thus, potash could have helped to boost the biogas production. More studies should be done on how local organic materials can be useful for the production of more biogas.
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Adamma C. E., Ibeaja,, Nwaogazie, Ify L., and Udeh, N. U. "Temperature Effect on Biogas Production from Co-digestion of Food Waste, Potash and Cow Dung." Journal of Engineering Research and Reports 24, no. 6 (February 28, 2023): 21–28. http://dx.doi.org/10.9734/jerr/2023/v24i6821.
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Temperature influence on biogas production from co-digestion of substrate (food waste, potash and cow dung) was investigated. Different concentrations of the substrate (4% to 12%) were mixed and loaded into the anaerobic digesters to produce biogas. Results of temperature effects on the biogas volume indicated that as the days of production increased, the temperature in the digesters increases and the volume of the biogas produced also increased. For digester B1 to B5, the temperature increase ranged from 10.1 to 44.5oC while the volume of the biogas produced increased from 11.3 to 25.9; 15.3 to 30.9; 10.1 to 34.5; 18.5 to 36.0 and 18.8 to 36m3/day for digesters B1, B2, B3, B4 and B5 respectively. For digesters B6 to B9, the temperature increase ranged from 20.6 to 48.4oC while the volume of the biogas produced increased from 22.1 to 40.2; 20.6 to 41.5; 24.9 to 42.0 and 24.2 to 42.5m3/day for digesters B6, B7, B8 and B9 respectively. A total 17859.6m3 of biogas was generated for a period of 90 days. Average temperature ranges from 29.30 ± 3.00oC for digester B1 (4% concentration of sample) to 41.46 ± 4.33oC of digester B8 (11% concentration of sample). This result was further clarified from the Analysis of variance and multiple comparisons of the temperature which revealed that digesters B5, B8 and B9 had no significant difference among them. The correlation of temperature and volume of biogas generated by each digester revealed that temperature significantly influenced the quantity of biogas generated at P= 0.01 and r = 0.760 (B2G), r = 0.740(B3G), r = 0.721(B6G) and r = 0.650(B8G) showing relationship were significant and had a high relationship between temperature and the substrates.
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Bortolini, Joseane, Maria Hermínia Ferreira Tavares, Dayane Taine Freitag, and Osvaldo Kuczman. "Removal of solids and chemical oxygen demand in poultry litter anaerobic digestion with different inocula." Ambiente e Agua - An Interdisciplinary Journal of Applied Science 15, no. 2 (March 26, 2020): 1. http://dx.doi.org/10.4136/ambi-agua.2469.
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Population growth has contributed to increasing poultry production, entailing a high waste loading, mainly poultry litter. One of the alternatives to treat such residues is anaerobic digestion, in which digester startup and generated-digestate quality are related to the material to be digested and to operation conditions, wherein inoculum use is one of the factors. This study therefore aimed to investigate how digestates, such as inocula, influence poultry litter (PL) anaerobic digestion, as well the reduction of solids and chemical oxygen demand (COD). For this, two inocula (bovine and swine digestates) were tested in the digestion process. The inocula were added at loads of 0.67, 1.00 and 1.67 gVS.L-1day-1. A split-plot design was developed and data underwent analysis of variance with means compared by the Tukey's test at 5% significance. Concerning bovine and swine inocula, it was concluded that both are indicated in the process. However, swine inoculum is better indicated because it had a better removal of total solids (TS), volatile solids (VS) and COD.
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Lissens, G., P. Vandevivere, L. De Baere, E. M. Biey, and W. Verstraete. "Solid waste digestors: process performance and practice for municipal solid waste digestion." Water Science and Technology 44, no. 8 (October 1, 2001): 91–102. http://dx.doi.org/10.2166/wst.2001.0473.
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The most common types of anaerobic digesters for solid wastes have been compared based on biological and technical performance and reliability. Batch systems have the most simple designs and are the least expensive solid waste digesters. They have high potential for application in developing countries. Two-stage systems are the most complex and most expensive systems. Their greatest advantage lies in the equalisation of the organic loading rate in the first stage, allowing a more constant feeding rate of the methanogenic second stage. Two-stage systems with biomass accumulation devices in the second stage display a larger resistance toward toxicants and inhibiting substances such as ammonia. However, the large majority of industrial applications use one-stage systems and these are evenly split between ‘dry’ systems (wastes are digested as received) and ‘wet’ systems (wastes are slurried to about 12% total solids). Regarding biological performance, this study compares the different digester systems in terms of organic loading rates and biogas yields considering differences in input waste composition. As a whole, ‘dry’ designs have proven reliable due to their higher biomass concentration, controlled feeding and spatial niches. Moreover, from a technical viewpoint the ‘dry’ systems are more robust and flexible than ‘wet’ systems.
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Rusten, Bjorn, and Ashish K. Sahu. "Microalgae growth for nutrient recovery from sludge liquor and production of renewable bioenergy." Water Science and Technology 64, no. 6 (September 1, 2011): 1195–201. http://dx.doi.org/10.2166/wst.2011.722.
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Proof-of-concept has been demonstrated for a process that will utilize nutrients from sludge liquor, natural light, and CO2 from biogas to grow microalgae at wastewater treatment plants. This process will reduce the impact of returning side-streams to the head of the plant. The produced algae will be fed to anaerobic digesters for increased biogas production. Dewatering of anaerobically digested sludge in centrifuges produces reject water with extremely low transmittance of light. A pre-treatment procedure was developed that improved light transmittance for reject water from the FREVAR, Norway, wastewater treatment plant from 0.1% T to 77% T (670 nm, 1 cm path). Chlorella sp. microalgae were found to be suitable for growth in this pre-treated reject water. Typical nitrogen removal was 80–90 g N/kg TSS of produced microalgae. The microalgae were successfully harvested by chemically assisted flocculation followed by straining through a 33 μm sieve cloth, achieving up to 99% recovery. Harvested algae were anaerobically co-digested with wastewater sludge. The specific methane gas production (mL CH4/g VS fed) for the algae varied from less than 65% to 90% of the specific methane gas production for the wastewater sludge, depending on digester temperature, retention time and pre-treatment of the algae biomass.
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Britz, T. J., G. Spangenberg, and C. A. Venter. "Acidogenic microbial species diversity in anaerobic digesters treating different substrates." Water Science and Technology 30, no. 12 (December 1, 1994): 55–61. http://dx.doi.org/10.2166/wst.1994.0581.
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Microbial species diversity was determined for the acidogenic populations of four different digesters treating landfill leachate, a petrochemical effluent and sewage. The digesters were a downflow fixed-bed, conventional, cold conventional and an upflow hybrid design. The 288 strains isolated from the digesters were characterized using API test systems and identifications confirmed using current taxonomic methods. The taxonomic diversity was determined using the Shannon (H′) and equitability (J′) indices. The species from the four digesters were very similar with the exception of those from the digester treating the landfill leachate. The higher diversity in the latter was probably due to the diverse composition of the leachate, suggesting that members of this population were more generalists, as opposed to the more narrowly constrained members in the other three digesters. The data indicated that in a digester environment dominated by a more specific carbon containing effluent, like a petrochemical effluent, the population becomes stenotolerant and is characterized by a lower species diversity. Such a population would not be able to cope as well with environmental fluctuations. With a more diverse substrate like the landfill leachate, generalists, having a wider range for environmental variables, would dominate. This is important in terms of anaerobic digester process efficiency and stability.
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Wang, Yan, and Shan Shan Zhang. "The Investigation Based on Heating with Biomass Energy for Biogas Digesters Winter Gas Production Technology in Cold Regions." Advanced Materials Research 1008-1009 (August 2014): 107–10. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.107.
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The average temperature is low in cold regions; therefore, under natural conditions, the gas production is more unlikely to be successful. When temperature drops below 6 °C in the biogas digester, it stops producing gas. By aiming household biogas digesters as subjects, from the test materials, experimental methods, experimental test results and economic analysis, this experiment studied the feasibility of heating with biomass energy for biogas digester to accomplish the digesters gas production in winter in in cold regions.
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A, Adewumi, Lasisi K. H, Akinmusere O. K, Ojo A. O, and Babatola J. O. "COMPARATIVE STUDY OF ELECTROLYSIS-ENHANCED ANAEROBIC DIGESTION OF THREE SOLUBLE SOLID WASTES FOR BIOGAS PRODUCTION." INDONESIAN JOURNAL OF URBAN AND ENVIRONMENTAL TECHNOLOGY 4, no. 1 (October 11, 2020): 11. http://dx.doi.org/10.25105/urbanenvirotech.v4i1.8004.
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<p><strong>Aim</strong>: A comparative study of biogas production from three soluble solid wastes was conducted under anaerobic conditions by subjecting each waste to both conventional and electrolyzed digesters. <strong>Methodology and Results</strong>: Varying weight of each of the waste was mixed thoroughly with water and fed into five digesters. Three of these digesters were electrolytically-enhanced while the other two were not. The digestion of each of the wastes was monitored for 40 days at an ambient temperature ranging from 24 to 35oC. In all the digesters, biogas production started on the day 2, and attained maximum value on day 14 to17. Biogas production ended on the day 34 and 35 in digester 1a, 1b, 2a and 2b with production ending earliest in digester 3 containing wastewater on day 19. The highest biogas was produced in digester 2b containing electrolyzed digester loaded with poultry droppings) with a cumulative volume percentage of 91.41 as compared to its conventional state with a cumulative volume percentage of 85.19 and both states of the cow dung waste with cumulative volume percentages of 77.26 and 71.64 respectively. The least production occurred in digester 3 with a cumulative volume percentage of 4.59. <strong>Conclusion, significance and impact study</strong>: It is therefore concluded that poultry droppings has the greatest potentials for the generation of biogas as compared to cow dung in conventional and electrolyzed state and wastewater.</p>
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Harrison, Ogala, and Ige Ayodeji Rapheal. "Biogas production from blends of fonio husk and donkey dung via anaerobic digestion for sustainable development." International Journal of Advanced Chemistry 9, no. 1 (December 25, 2020): 1. http://dx.doi.org/10.14419/ijac.v9i1.31254.
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There is growing public concern over potential impact on environmental quality caused by animal wastes. Anaerobic digestion, a biological conversion process can be used to obtain energy from biologicall wastes. This study explored the production of biogas from co-digestion of fonio hus and donkey dung using anaerobic biological conversion. The digesters were labeled as; digester A –Fonio husk only, digester B - donkey dung only, digester C – Fonio husk (300g) and Donkey Dung (200g), digester D – Fonio husk (200g) and donkey dung (300g). Proximate analysis of the substrates before and after digestion were determined such as total solids (TS), volatile solid, carbon content, nitrogen content, ash content, etc., and pH before and after digestion process. The biogas produced during this period was collected by water displacement method and subsequently measured. The results showed that Fonio husk in bio-digesters A and B gave a cumulative average biogas volume of 4972 ml and 5222 ml (week 3) while pig dung in bio-digesters C and D gave a cumulative average biogas volume of 5564 ml and 5978 respectively (week 3) within three weeks of fermentation. The digester is capable of producing 0.007m at average working temperature of 320C. Digester D produces higher volume of biogas as a result of improved nutrient provide by donkey dung as shown in the results obtained from the proximate analysis and has the best neutral pH, there was a reduction in the startup time.
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Trout, Paul A. "INERT GAS PURGING OF ANAEROBIC DIGESTERS AND DIGESTER GAS SYSTEMS." Proceedings of the Water Environment Federation 2000, no. 10 (January 1, 2000): 654–66. http://dx.doi.org/10.2175/193864700784545559.
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Dvornik, Ye O. "Biotechnology of co-fermentation of sugar by-products with typical agricultural substrates." Naukovij žurnal «Tehnìka ta energetika» 11, no. 3 (November 18, 2020): 135–41. http://dx.doi.org/10.31548/machenergy2020.03.135.
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Anaerobic digestion (AD) is a promising option for the environmentally friendly recycling of agricultural by-products. However, overloading of the digester with sugar, starch or protein might cause inhibition of the anaerobic processes. The aim of the present project was to investigate the influence of sugar beet by products on biogas yield from a typical mixture of energy crops and animal manure. The investigated substrates have been: cattle slurry, maize, sorghum and grass silage, sugar beet pulp e (SBP) and sugar beet tail silage (SBT). The difference between untreated SBT to processed SBP. All substrates were digested in 1 l eudiometer-batch digesters at 37.5°C during 28 to 38 days. The specific methane yield of mixtures and various substrates exanimated. The experiments showed that edition of sugar beet by product to energy crop and slurry mixture results in high methane yield even the achieved methane yield of the mixture was lower the expected.
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De Leén, C., and D. Jenkins. "Removal of fecal coliforms by thermophilic anaerobic digestion processes." Water Science and Technology 46, no. 10 (November 1, 2002): 147–52. http://dx.doi.org/10.2166/wst.2002.0314.
Full textAbstract:
Recent U.S. EPA regulations (40 CFR Section 503) specify maximum concentrations of pathogens and metals for Class A wastewater treatment plant sludges. The most common sludge process is mesophilic (35¡C) digestion which stabilizes the solids, produces a combustible gas but does not create an effluent that meets the 503 Class A pathogen requirements. This investigation was conducted to determine whether anaerobic digestion processes incorporating a thermophilic stage could achieve 503 Class A pathogen levels. The research reported here was a bench-scale screening study meant to identify the most promising process alternatives for further investigation. Fecal Coliform (FC) concentrations were used to assess disinfection efficiency. Digesters were 30 L capacity fed semi-continuously in draw-fill mode. Digester startup was rapid to produce true thermophiles. Temperature staging and pH were assessed in 3 sets of experiments: Set 1 were one stage (“acid phase”), Set 2 were one stage (“acid + methane phases”) and Set 3 were two stage (“acid phase” then “methanogenic phase”). Feed was a 1:1 mixture of Thickened Waste Activated Sludge and Primary Sludge. The following anaerobic digestion configurations and operating parameters allowed the production of digested sludge with a mean FC concentration statistically less than 103 (the regulatory value for Class A sludge): thermophilic single stage acid phase at 52 and 62°C; thermophilic single stage acid + methane phase at 48°C, 52°C and 62°C; two-stage mesophilic acid phase followed by mesophilic methane phase; two stage mesophilic acid phase followed by thermophilic methane phase at 48°C, 52°C and 62°C. If the maximum digested FC concentration must be below 103 MPN/g TS then the following digester configurations and operating conditions will be compliant: two stage mesophilic acid phase followed by thermophilic methane phase at 52°C and 62°C.
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Frigon, J. C., T. Bruneau, R. Moletta, and S. R. Guiot. "Coupled anaerobic–aerobic treatment of whey wastewater in a sequencing batch reactor: proof of concept." Water Science and Technology 55, no. 10 (May 1, 2007): 201–8. http://dx.doi.org/10.2166/wst.2007.323.
Full textAbstract:
A proof of concept was performed in order to verify if the coupling of anaerobic and aerobic conditions inside the same digester could efficiently treat a reconstituted whey wastewater at 21 °C. The sequencing batch reactor (SBR) cycles combined initial anaerobic phase and final aerobic phase with reduced aeration. A series of 24 h cycles in 0.5 L digesters, with four different levels of oxygenation (none, 54, 108 and 182 mgO2 per gram of chemical oxygen demand (COD)), showed residual soluble chemical oxygen demand (sCOD) of 683±46, 720±33, 581±45, 1,239±15 mg L−1, respectively. Acetate and hydrogen specific activities were maintained for the anaerobic digester, but decreased by 10–25% for the acetate and by 20–50% for the hydrogen, in the coupled digesters. The experiment was repeated using 48 h cycles with limited aeration during 6 or 16 hours at 54 and 108 mgO2gCOD−1initial, displaying residual sCOD of 177±43, 137±38, 104±22 and 112±9 mg L−1 for the anaerobic and the coupled digesters, respectively. The coupled digesters recovered after a pH shock with residual sCOD as low as 132 mg L−1 compared to 636 mg L−1 for the anaerobic digester. With regard to the obtained results, the feasibility of the anaerobic- aerobic coupling in SBR digesters for the treatment of whey wastewater was demonstrated.
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Anderson, B. C., and D. S. Mavinic. "Improvement in aerobic sludge digestion through pH control: initial assessment of pilot-scale studies." Canadian Journal of Civil Engineering 14, no. 4 (August 1, 1987): 477–84. http://dx.doi.org/10.1139/l87-072.
Full textAbstract:
Waste-activated sludges from an extended-aeration, pilot-scale wastewater treatment facility and a high-rate, full-scale system were aerobically digested in 150 L pilot-scale digesters, operated in a semicontinuous (daily fill-and-draw) mode, at a standard 15-day solids retention time (SRT). To offset the mixed-liquor pH (MLpH) decrease normally encountered in these digesters (as a result of nitrification), hydrated lime and sodium bicarbonate were used in separate experiments to control MLpH in the series pH 6, 7, 8, and 9. Digester performance in the first stage of this work was assessed solely on the basis of reduction in total volatile suspended solids.The extended-aeration type sludge exhibited the greatest improvement in process performance under all pH-controlled conditions. Improvements in digestion efficiency of up to 80% over the uncontrolled reactors were noted. The use of lime resulted in greater digestion enhancement than did sodium bicarbonate with this sludge, without a significant increase in sludge solids production (owing to the low chemical doses required). Digestion efficiency of the high-rate type sludge was little improved (on a relative basis) with either chemical; however, absolute efficiencies in the individual digesters were, in some cases, nearly double those of the comparative extended-aeration sludge digesters. This difference appears to be a function of the process from which the digesting sludge originated, and seems to be influenced by the amount of easily oxidizable, endogenous substrate contained in the biomass. It was concluded that the extended-aeration type sludge was most amenable to enhanced digestion through pH control; as well, cost and process considerations made lime the chemical of choice. Key words: activated sludge, aerobic digestion, hydrated lime, mixed-liquor pH control, nitrification, process enhancement, pilot-scale, sodium bicarbonate.
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Noike, T., and J. Matsumoto. "Upgrading of Anaerobic Digestion Processes for Night Soil." Water Science and Technology 18, no. 7-8 (July 1, 1986): 249–56. http://dx.doi.org/10.2166/wst.1986.0296.
Full textAbstract:
The upgrading of night soil anaerobic digestion processes was studied by field investigation of the performance of anaerobic digesters in existing night soil treatment plants and by serai-continuous experiments with bench-scale digesters. Both the average monthly amount of collected night soil fed to a digester and the concentration of volatile solids in night soil increased in winter. A good correlation was found to exist between gas production and digestion temperature. The COD removal rate in the first digester was markedly higher than that in the second digester. The stirring period in the first digester in one plant differs from that in the other plant. Stirring the first digester for too long a period reduces the rate of COD removal by the second digester in the two-stage anaerobic digestion process. The first digester should be stirred for more than one hour per day in order to promote gas production. Gas production and CODCr removal rate in the second digester were hardly affected by reductions in retention time ranging from 15 days to 5 days. As night soil contains a large amount of cellulose and other refractory organics, some kind of pretreatment of the night soil fed to the digester may be necessary for the promotion of acidogenesis in the two-phase anaerobic digestion process.
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Sacks, J., and C. A. Buckley. "Anaerobic treatment of textile size effluent." Water Science and Technology 40, no. 1 (July 1, 1999): 177–82. http://dx.doi.org/10.2166/wst.1999.0038.
Full textAbstract:
This investigation focused on the KwaZulu-Natal province, where a number of under-utilised and under-performing anaerobic digesters were identified. The aim of the study was to assess the potential for treatment of high-strength or toxic organic agro-industrial effluents in the available capacity. The anaerobic digestion of a textile size effluent was investigated. Inhibitory components and concentrations of the solution were identified. The size solution was degraded anaerobically but could cause overloading of a digester at high concentrations. The performance efficiency of the anaerobic digesters at the Umbilo Sewage Purification Works was evaluated. The digesters were operating efficiently and had available hydraulic and organic capacities. This investigation confirmed the potential for the treatment of high-strength organic effluents in the available anaerobic digester capacity.
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Abubakar, M. S., A. B. Yazid, A. A. Sabo, A. Ibrahim, A. U. Aliyu, and M. Saleh. "EFFECTS OF TEXTILE WASTEWATER PRE-TREATMENT ON LIGNOCELLULOSIC BIOMASS FOR SOLID-STATE ANAEROBIC DIGESTION." FUDMA JOURNAL OF SCIENCES 7, no. 1 (February 28, 2023): 156–64. http://dx.doi.org/10.33003/fjs-2023-0701-1267.
Full textAbstract:
Researchers are looking into sustainable and inexpensive energy sources due to the constant rise in the price of fossil fuels, greenhouse gas emissions, and dependence on non-renewable energy sources. In this study, wastewater from the textile industry is co-digested with lignocellulosic biomass (wheat straw) to produce biogas. During 21 days, five anaerobic digesters were run at room temperature (28 to 30 0C). Wheat straw inoculated with cow manure was put into wheat straw operating in five digesters at five different ratios of wastewater to distilled water. It has been discovered that the slurry digested with mere wastewater (not diluted with distilled water) has the lowest production, while the slurry digested with wheat straw and cow dung has the highest production.
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Syed Sabeer Ali, S. N., R. Omar, H. Che Man, A. I. Md Idris, and H. A. Tajuddin. "Foaming Tendency in Anaerobic Digestion of Wastewater Inoculated with Anaerobic Sludge and Cow Manure: Effect of Protein Concentration." IOP Conference Series: Materials Science and Engineering 1257, no. 1 (October 1, 2022): 012043. http://dx.doi.org/10.1088/1757-899x/1257/1/012043.
Full textAbstract:
Abstract Foaming has impacted the digestion process causing severe process failures. The basis of foaming is often unclear due to multiple foaming compounds in a single system. This study aims to elucidate the effect of protein concentration on foaming in anaerobic sludge and cow manure (CM) digesters inoculated with synthetic wastewater as a substrate. Gelatine was used to alter the protein concentration in the digesters. The foaming tendency, biogas production, protein, and chemical oxygen demand (COD) removal were measured to comprehend the findings. The results show that the foaming tendency increased with protein concentration in anaerobic sludge digesters. It also had the highest biogas production. There was no evident process inhibition observed in the anaerobic sludge digester, even at higher protein and COD concentrations. For CM digester, the foaming tendency and biogas production increased to 9 g/L; however, the biogas production decreased with increased substrate protein concentration, indicating process inhibition. The results indicate that the biogas production, foaming tendency, COD and protein removal increased steadily for both digesters. However, the trend decreased for CM digester at increased protein concentrations. This study also concluded that protein creates foaming when inoculated with anaerobic sludge and CM even at low substrate protein concentration.
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Loughrin, John, Stacy Antle, Karamat Sistani, and Nanh Lovanh. "In Situ Acoustic Treatment of Anaerobic Digesters to Improve Biogas Yields." Environments 7, no. 2 (February 8, 2020): 11. http://dx.doi.org/10.3390/environments7020011.
Full textAbstract:
Sound has the potential to increase biogas yields and enhance wastewater degradation in anaerobic digesters. To assess this potential, two pilot-scale digestion systems were operated, with one exposed to sound at less than 10 kHz and with one acting as a control. Sounds used were sine waves, broadband noise, and orchestral compositions. Weekly biogas production from sound-treated digesters was 18,900 L, more than twice that of the control digester. The sound-treated digesters were primarily exposed to orchestral compositions, because this made cavitational events easier to identify and because harmonic and amplitude shifts in music seem to induce more cavitation. Background recordings from the sound-treated digester were louder and had more cavitational events than those of the control digester, which we ascribe to enhanced microbial growth and the resulting accelerated sludge breakdown. Acoustic cavitation, vibrational energy imparted to wastewater and sludge, and mixing due to a release of bubbles from the sludge may all act in concert to accelerate wastewater degradation and boost biogas production.