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Morel, E., K. Santamaria, M. Perrier, S. R. Guiot i B. Tartakovsky. "Multi-wavelength fluorometry for anaerobic digestion process monitoring". Water Science and Technology 52, nr 1-2 (1.07.2005): 465–71. http://dx.doi.org/10.2166/wst.2005.0554.
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Applicability of multi-wavelength fluorometry for anaerobic digestion process monitoring was investigated in a 3.5 L upflow anaerobic sludge bed (UASB) lab-scale reactor. Both off-line and on-line monitoring of key process parameters was tested. Off-line emission spectra were measured at an angle of 90° to the excitation beam using a cuvette. On-line measurements were carried out using a fiber optic probe in the external recirculation line of the digester. Fluorescence spectra were correlated to available analytical measurements to obtain partial least square regression models. An independent set of measurements was used to validate the regression models. Model estimations showed reasonable agreement with analytical measurements with multiple determination coefficients (R2) between 0.6 and 0.95. Results showed that off-line fluorescence measurements can be used for fast estimation of anaerobic digestor effluent quality. At the same time, the on-line implementation of multi-wavelength fluorescence measurements can be used for real-time process monitoring and, potentially, for on-line process control.
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Sacks, J., i C. A. Buckley. "Anaerobic treatment of textile size effluent". Water Science and Technology 40, nr 1 (1.07.1999): 177–82. http://dx.doi.org/10.2166/wst.1999.0038.
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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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Sousa, Francine Aparecida, Alessandro Torres Campos, Pedro Ivo Sodré Amaral, Daiane Cecchin i Alessandro Vieira Veloso. "PRODUÇÃO DE BIOGÁS PROVENIENTE DE CAMAS SOBREPOSTAS DE SUÍNOS". ENERGIA NA AGRICULTURA 32, nr 3 (20.12.2017): 229. http://dx.doi.org/10.17224/energagric.2017v32n3p229-236.
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Foi avaliada a eficiência do processo de biodigestão anaeróbia e a produção de biogás proveniente de cama sobreposta de suínos em fase de terminação, em biodigestores de bancada. Foram utilizados 12 protótipos de biodigestores laboratoriais de batelada, confeccionados em recipiente plástico e PVC com o volume utilizado de 20 litros. Os tratamentos constituíram-se de dois materiais de cama sobreposta de suínos como substrato, diluídas em água: Tratamento (M+B) - cama de maravalha+bagaço de cana e tratamento (MAR) - cama de maravalha. Para cada tratamento, foi avaliado o potencial poluidor do efluente, por meio de parâmetros físico-químicos (pH, DBOt, DQOt e ST). Foi quantificada a produção de biogás a fim de verificar o potencial energético da cama sobreposta de suínos. Observou-se que, o tratamento (MAR) apresentou maiores valores de redução de ST. A eficiência de remoção de DQOt para a cama (M+B) foi de 66,04%, já para a cama (MAR) obteve-se redução de 30,80%. A produção do biogás proveniente da cama (M+B) foi significativamente superior à cama (MAR). O uso de biodigestores é interessante para promover o pós-tratamento (ou tratamento complementar) do efluente, obtendo-se, ainda, produção de energia na forma de biogás, que pode ser convertida em eletricidade, aumentando a sustentabilidade da granja. As camas sobrepostas de suínos, submetidas à biodigestão anaeróbia, tiveram reduções significativas dos conteúdos dos ST, SVT e DQO. A produção do biogás proveniente da cama sobreposta composta por maravalha+bagaço de cana foi significativamente superior à cama sobreposta composta por maravalha.PALAVRA-CHAVE: biodigestores, biodigestão anaeróbia, carga orgânica, instalações para suínos. PRODUCTION OF BIOGAS ORIGINATED FROM SWINE SUPERIMPOSED BEDSThe objective of this study was to evaluate the efficiency of the anaerobic bio-digestion process and the production of biogas derived from superimposed beds of finishing swine, in tabletop biodigestors. Twelve continuous laboratory bio-digestor prototypes, assembled in plastic and PVC recipients, were used. The treatments constituted of two superimposed bed materials as substrate, diluted in water: Treatment S+B – wood shavings + sugarcane bagasse bed; and treatment SHA – wood shavings bed. For each treatment, the pollutant potential of the effluent was evaluated, by means of physical-chemical parameters (pH, DBOt, DQOt and ST). The production of biogas was quantified in order to verify the energetic potential of the beds. The SHA treatment presented higher ST reduction values. The S+B bed efficiency of DQOt removal was 66.04%, while the SHA bed was of 30.80%. The production of biogas originated from the superimposed bed constituted of sugarcane bagasse + wood shavings was significantly superior to the superimposed bed constituted of wood shavings. With this study, it was possible to conclude that the use of bio-digesters is interesting to promote the post-treatment (or complementary treatment) of the effluent, resulting on bioenergy generation, contributing to the system sustainability. Superimposed pig beds submitted to anaerobic biodigestion had significant reductions in ST, SVT and DQOt contents. The production of biogas from the overlapped bed composed of wood shavings + sugarcane bagasse was significantly superior to the superposed bed composed of wood shavings.KEYWORDS: Modeling bio-digestors, anaerobic bio-digestion, organic charge, facilities for swine
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Sacks, J., C. A. Buckley, E. Senior i H. Kasan. "An assessment of the feasibility of anaerobic digestion as a treatment method for high strength or toxic organic effluents". Water Science and Technology 39, nr 10-11 (1.05.1999): 347–51. http://dx.doi.org/10.2166/wst.1999.0680.
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The anaerobic digestion process converts organic materials into a methane-rich biogas. The KwaZulu-Natal region has the potential to attract a significant amount of industry. The objective of this research was to assess the feasibility of using anaerobic digestion as a treatment method for high-strength or toxic organic effluents. A strategy was developed to evaluate the degradability and toxicity of effluents and, ultimately, predict the efficiency of treatment in a full-scale digester. This paper details the strategy and investigates the degradation potential of a textile size effluent (COD ca. 140,000 mg/l). The ultimate degradability of the effluent was determined as well as the concentrations and volumes, which could be treated effectively. The inhibitory components of the size effluent were found to be Plystran (10 mg/l) and the biocide (5 mg/l). Anaerobic digestion was found to be feasible, on a laboratory-scale. These results are being applied for scale-up, to full-scale implementation in an existing anaerobic digester.
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Sasaki, Ken, Tohru Tanaka, Yoshinori Nishizawa i Mitsunori Hayashi. "Production of a herbicide, 5-aminolevulinic acid, by Rhodobacter sphaeroides using the effluent of swine waste from an anaerobic digestor". Applied Microbiology and Biotechnology 32, nr 6 (marzec 1990): 727–31. http://dx.doi.org/10.1007/bf00164749.
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Gunnarsson, Anita, Börje Lindén i Ulla Gertsson. "Biodigestion of Plant Material Can Improve Nitrogen Use Efficiency in a Red Beet Crop Sequence". HortScience 46, nr 5 (maj 2011): 765–75. http://dx.doi.org/10.21273/hortsci.46.5.765.
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Nitrogen (N) tied up in or lost from decomposing biomass decreases the residual N effects of green manure and of other crop residues. During anaerobic degradation in a biogas digestor (biodigestion), N mineralization takes place under conditions in which losses can be kept to a minimum. Therefore, biodigestion of green manure biomass and beet foliage was tested to generate readily available N and compared with a direct green manure fertilization system. The effluent was applied as fertilizer in field experiments on a sandy soil as a tool for improving N supply for an organic farming system. Data from the field experiments were used for simulating the amount of net inorganic N equivalents (inorganic N equivalents from effluent plus inorganic N equivalents from pre-crops) in three crop sequences: A) green manure ley, red beets, winter rye; B) harvested ley, red beets, winter rye; and C) harvested ley, spring barley, red beets in which (B) and (C) represented biogas nutrient management systems and (A) a green manure system. When all available effluent from biogas production from 1 ha of grass–clover ley with two or three harvests (2H-ley or 3H-ley) and one hectare of beet foliage was used as a fertilizer for red beets (Beta vulgaris var. conditiva Alef) after barley (Hordeum vulgare L.), the yield of marketable red beets increased by 5.7 Mg·ha−1 (33%) with effluent from 2H-ley and beet foliage and 9.1 Mg·ha−1 (53%) with effluent from 3H-ley and beet foliage compared with red beets grown without effluent fertilization after a green manure ley. When total dry matter production was taken into account, the advantage for the BG systems with 2H- and 3H-ley was 15% and 28%, respectively. The nitrate concentration in the red beets was not higher with effluent supplied at this level than with green manure as the only N source. The simulated amount of net inorganic N equivalents was 128 kg N for the whole of crop sequence (C) with 1 ha of each crop and where effluent supply to red beets was based on digested biomass in ley and beet tops. The corresponding amount of net inorganic N equivalents for the green manure crop sequence (A), in which no effluent was supplied, was 73 kg N. Unused soil mineral N (0- to 90-cm depth) at red beet harvest indicated that the risk of leaching in BG systems was lower than in GrM systems (88, 76, and 61 kg Nmin/ha left after unmanured beets after Gr-M-ley, low manured beets after 3H-ley and high manured beets after barley, respectively). Effluent fertilization of red beets directly after 2H- and 3H-ley gave unexpectedly low yield responses compared with red beets after barley. The reasons may be the result of nutritional imbalance of other nutrients than N or may be plant pathological in nature. The conclusion is that a nutrient management system with biodigestion can increase net inorganic N equivalents and reduce risk for N leaching, but inappropriate use of the effluent, i.e., at an unsuitable point in the crop rotation, may negate the benefits.
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Abid, Aasima, Huriyah Khan, Tehseen Fatima Zeb, Syed Muneeb Uddin, Rafat Amin, Sadaf Khan i Shaukat Ali. "Macromolecular characterization and growth kinetics of Arthrospira platensis and Chlorella Vulgaris as affected by different media (synthetic and Anaerobic Digestor Effluent) - A comparative study." INTERNATIONAL JOURNAL OF ENDORSING HEALTH SCIENCE RESEARCH (IJEHSR) 8, nr 4 (1.12.2020): 188–201. http://dx.doi.org/10.29052/ijehsr.v8.i4.2020.188-201.
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Abid, Aasima, Huriyah Khan, Tehseen Fatima Zeb, Syed Muneeb Uddin, Rafat Amin, Sadaf Khan i Shaukat Ali. "Macromolecular characterization and growth kinetics of Arthrospira platensis and Chlorella Vulgaris as affected by different media (synthetic and Anaerobic Digestor Effluent) - A comparative study." INTERNATIONAL JOURNAL OF ENDORSING HEALTH SCIENCE RESEARCH (IJEHSR) 8, nr 4 (1.12.2020): 188–201. http://dx.doi.org/10.29052/ijehsr.v8.i4.2020.188-201.
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Hemmati, Sadaf, M. Mostafa Elnegihi, Chee Hoong Lee, Darren Yu Lun Chong, Dominic C. Y. Foo, Bing Shen How i ChangKyoo Yoo. "Synthesis of Large-Scale Bio-Hydrogen Network Using Waste Gas from Landfill and Anaerobic Digestion: A P-Graph Approach". Processes 8, nr 5 (26.04.2020): 505. http://dx.doi.org/10.3390/pr8050505.
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Due to the expanding concern on cleaner production and sustainable development aspects, a technology shift is needed for the hydrogen production, which is commonly derived from natural gas. This work aims to synthesise a large-scale bio-hydrogen network in which its feedstock, i.e., bio-methane, is originated from landfill gas and palm oil mill effluent (POME). Landfill gas goes through a biogas upgrader where high-purity bio-methane is produced, while POME is converted to bio-methane using anaerobic digestor (AD). The generated bio-methane is then distributed to the corresponding hydrogen sink (e.g., oil refinery) through pipelines, and subsequently converted into hydrogen via steam methane reforming (SMR) process. In this work, P-graph framework is used to determine a supply network with minimum cost, while ensuring the hydrogen demands are satisfied. Two case studies in the West and East Coasts of Peninsular Malaysia are used to illustrate the feasibility of the proposed model. In Case Study 1, four scenarios on the West Coast have been considered, showing total cost saving ranging between 25.9% and 49.5%. This showed that aside from the positive environmental impact, the incorporation of bio-hydrogen supply can also be economically feasible. Such benefits can also be seen in Case Study 2, where the uptake of biogas from landfill and POME sources on the East Coast can lead to a 31% reduction on total network cost. In addition, the effect of bio-hydrogen supply network on carbon footprint reduction was analysed in this work.
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Rönner-Holm, S. G. E., A. Żak i N. C. Holm. "Comparison of different conditions, substrates and operation modes by dynamic simulation of a full-scale anaerobic SBR plant". Water Science and Technology 65, nr 3 (1.02.2012): 558–66. http://dx.doi.org/10.2166/wst.2012.887.
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Simulation studies for a full-scale anaerobic unit of a wastewater treatment plant (WWTP) were performed using the anaerobic digestion model no. 1 (ADM1). The anaerobic full-scale plant consists of one mesophilic and one thermophilic digester, operated in an anaerobic sequential batch reactor (ASBR) mode, and sludge enrichment reactors (SER) for each digester. The digesters are fed with a mixture of vegetable waste and process wastewater from the food factory. Characteristics such as CODtotal, Ntotal and NH4-N concentrations in the influent and effluent of the digester and SERs were measured and used for input fractionation. Parameters such as level, pH, biogas amount and composition in the digester were measured online and used for calibration. For simulation studies, different temperatures and operation modes with varying chemical oxygen demand (COD) input loads corresponding to feedstocks such as fruits, vegetables and grain were analysed and compared. Higher gas production and digestion efficiency in the thermophilic reactor and in shorter cycles were found and confirmed at full scale. Serial operation mode increased the gas production, but pH inhibition occurred earlier. Feeding only biosolids into digester I and the effluent of digester I together with process water into digester II further improved gas production in serial operation mode.
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Mirtsou-Xanthopoulou, Chrysoula, Ioannis V. Skiadas i Hariklia N. Gavala. "On the Effect of Aqueous Ammonia Soaking Pre-Treatment on Continuous Anaerobic Digestion of Digested Swine Manure Fibers". Molecules 24, nr 13 (5.07.2019): 2469. http://dx.doi.org/10.3390/molecules24132469.
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(1) Background: The continuously increasing demand for renewable energy sources renders anaerobic digestion as one of the most promising technologies for renewable energy production. Due to the animal production intensification, manure is being used as the primary feedstock for most biogas plants. Their economical profitable operation, however, relies on increasing the methane yield from the solid fraction of manure, which is not so easily degradable. The solid fraction after anaerobic digestion, the so-called digested fibers, consists mainly of hardly biodegradable material and comes at a lower mass per unit volume of manure compared to the solid fraction before anaerobic digestion. Therefore, investigation on how to increase the biodegradability of digested fibers is very relevant. So far, Aqueous Ammonia Soaking (AAS), has been successfully applied on digested fibers separated from the effluent of a manure-fed, full-scale anaerobic digester to enhance their methane productivity in batch experiments. (2) Methods: In the present study, continuous experiments at a mesophilic (38 °C) CSTR-type anaerobic digester fed with swine manure first and a mixture of manure with AAS-treated digested fibers in the sequel, were performed. Anaerobic Digestion Model 1 (ADM1) previously fitted on manure fed digester was used in order to assess the effect of the addition of AAS-pre-treated digested manure fibers on the kinetics of anaerobic digestion process. (3) Results and Conclusions: The methane yield of AAS-treated digested fibers under continuous operation was 49–68% higher than that calculated in batch experiments in the past. It was found that AAS treatment had a profound effect mainly on the disintegration/hydrolysis rate of particulate carbohydrates. Comparison of the data obtained in the present study with the data obtained with AAS-pre-treated raw manure fibers in the past revealed that hydrolysis kinetics after AAS pre-treatment were similar for both types of biomasses.
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Lin, C. Y., T. Noike, H. Furumai i J. Matsumoto. "A Kinetic Study on the Methanogenesis Process in Anaerobic Digestion". Water Science and Technology 21, nr 4-5 (1.04.1989): 175–86. http://dx.doi.org/10.2166/wst.1989.0221.
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Results obtained from experiments on two-phase anaerobic digestion using a high concentration of a volatile fatty acid (VFA) mixture were used to elucidate the kinetic mechanism of the methanogenesis process. The mixture consisted of the major intermediate products of anaerobic digestion, i.e., acetic acid (HAc), propionic acid (HPr) and butyric acid (HBu). The relationship between the rate of substrate utilization and substrate concentration in the digesters was in the form of a Michaelis-Menten equation. The rate-limiting step of the methanogenesis process, i.e., the conversion of HAc to methane, was speeded up in the digesters and this was proved kinetically. A method for determining kinetic constants for substrate-specific microorganisms was suggested. A simulation model for predicting the effluent substrate concentration was demonstrated. The effluent substrate concentration of an anaerobic digester fed by a multisubstrate was found to be simulatively predictable from its influent component substrates.
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Salsali, H. R., W. J. Parker i S. A. Sattar. "Impact of concentration, temperature, and pH on inactivation of Salmonella spp. by volatile fatty acids in anaerobic digestion". Canadian Journal of Microbiology 52, nr 4 (1.04.2006): 279–86. http://dx.doi.org/10.1139/w05-125.
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It is known that the presence of volatile fatty acids may play a role in the inactivation of pathogens for systems that employ an acid phase reactor. This study was conducted to investigate the influence of volatile fatty acids on the inactivation of Salmonella spp. over a range of digestion temperatures. In this study, digesters that were treating municipal wastewater treatment plant sludges were operated at temperatures that ranged from 35 to 49 °C and had a solids residence time of 15 days. Samples collected from the effluent of the digesters were dosed with solutions containing acetic, propionic, and butyric acids alone and in mixtures, and the dosed effluents were analyzed for Salmonella spp. over time. In the first round of testing, the digester effluents were dosed with individual organic acids and also a mixture containing all three volatile fatty acids over a range of concentrations from 750 to 6000 mg/L, and the pH of the samples was fixed at a value of 5.5. In the second round of testing, the sample sludges were spiked with a fixed amount of organic acid mixture, and the pH was varied from 4.5 to 7.5. The reduction of Salmonella spp. in digester effluents, when dosed with volatile organic acids, was found to depend on pH, temperature, the chain length of the acids, and the concentration and composition of the acids present. Increases in temperature appeared to increase the inhibitory effects of the volatile organic acids. At mesophilic temperatures, acidic pHs resulted in a greater inhibition of Salmonella spp.; whereas at higher temperatures neutral pHs were found to be more inhibitory. The results suggest that acid phase digesters that operate at elevated temperatures and low pH can achieve substantial reduction of Salmonella spp.Key words: anaerobic digestion, decay kinetics, mesophilic, Salmonella spp., volatile organic acids.
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Siegrist, H., W. Hunziker i H. Hofer. "Anaerobic digestion of slaughterhouse waste with UF-membrane separation and recycling of permeate after free ammonia stripping". Water Science and Technology 52, nr 1-2 (1.07.2005): 531–36. http://dx.doi.org/10.2166/wst.2005.0563.
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Anaerobic digestion can adapt to free ammonia to a certain extent. During the anaerobic digestion of slaughterhouse waste, however, an ammonia concentration of up to 15 g N l−1 can be reached in the sludge liquid and this will even inhibit adapted sludge. To lower this concentration, a fraction of the digester liquid must therefore be continuously separated from the digested sludge and the free ammonia stripped before the liquid is recycled to the digester. A mesophilic laboratory digester was successfully operated with an ammonium concentration of 4–5 g l−1 and a pH of 8.0–8.4. After free ammonia stripping, the excess liquid was treated in a laboratory SBR for nitrogen and phosphorus removal before being added to the receiving water. The effluent had no toxic effect on daphnia and algae.
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Marmanis, D., C. Emmanouil, A. Thysiadou, J. G. Fantidis, N. Kokkinos i V. Diamantis. "Combined electrochemical treatment coupled to anaerobic digestion effluents". Journal of Physics: Conference Series 2339, nr 1 (1.09.2022): 012025. http://dx.doi.org/10.1088/1742-6596/2339/1/012025.
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Abstract Electrochemical treatment is an effective method to improve physicochemical characteristics of effluents and to minimize the environmental footprint of anaerobic digestion facilities. In the present research an anaerobic digester effluent was subjected to post-treatment, using electro-oxidation or electrocoagulation processes for significant reduction of Chemical oxygen demand and ammonia. A combined electro-oxidation and electrocoagulation treatment was also performed. Results show satisfactory decrease of both Chemical oxygen demand and ammonium nitrogen, which however were relative to the method applied, the time duration and the current intensity. A combined use of both methods may be the best solution for the post-treatment of this high burden effluent. All the presented values have occurred from experiments in the Chemistry Department of the International Hellenic University.
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Kamarád, Luděk, Stefan Pohn, Günther Bochmann i Michael Harasek. "Determination of mixing quality in biogas plant digesters using tracer tests and computational fluid dynamics". Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 61, nr 5 (2013): 1269–78. http://dx.doi.org/10.11118/actaun201361051269.
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The total electricity demand of investigated biogas plants (BGP) makes up 7–8 % of the total electricity produced. Nearly 40 % of this energy is consumed just for mixing in digesters and the energy demand for mixing in some biogas plants can be even higher. Therefore, optimal mixing in anaerobic digesters is a basic condition for efficient plant operation and biogas production. The use of problematic substrates (e.g. grass silage or other fibrous substrates), installation of unsuitable mixing systems or inconvenient mixing intervals may lead to mixing problems. Knowledge about mixing in biogas digesters is still insufficient, so the objective of this study was to fill the information gaps in the literature by determining the minimal retention time of substrates fed into anaerobic digesters and to describe substrate distribution and washing out rates from investigated digesters. Two full-scale biogas plant digesters (2000 m3 and 1500 m3) using different mixing systems and substrates were investigated. To characterize the substrate distribution, lithium hydroxide monohydrate solutions were used for tracer tests at concentrations of 47.1 mg Li+ / kg TS and 46.6 mg Li+ / kg TS in digester. The tracer concentration in the digester effluents was measured during two hydraulic retention times and compared. Although the tracer was detected in the digester effluent at nearly the same time in both cases, the tracer tests showed very different distribution curves. The tracer concentration in effluent B grew much slower than in effluent A and no significant short circuiting streams were detected. Although the data calculated by computational fluid dynamics methods (CFD) showed a very good agreement with the full scale results, full comparison was not possible.
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Ruike, Wataru, Atsushi Higashimori, Junichi Yaguchi i Yu-you Li. "Use of real-time PCR with propidium monoazide for enumeration of viable Escherichia coli in anaerobic digestion". Water Science and Technology 74, nr 5 (30.06.2016): 1243–54. http://dx.doi.org/10.2166/wst.2016.327.
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A combination of propidium monoazide (PMA) with real-time quantitative polymerase chain reaction (PMA-qPCR) was optimized to enumerate only viable Escherichia coli in anaerobic digestion processes. Repeating the PMA treatment twice and a final concentration of 100 μM resulted in an effective exclusion of DNA from heat-treated E. coli cells. In three anaerobic digestion processes, real-time PCR, PMA-qPCR, and the most probable number method (MPN) were used to estimate the numbers of total, viable, and culturable E. coli cells, respectively. Culturable concentrations of fecal coliforms were also measured by the membrane filter method. For thermophilic digestion, the reductions in total and viable E. coli cells from the digester influent to the effluent were significantly lower than those in culturable cells and fecal coliforms by two to four orders of magnitude. For mesophilic digestion, the differences in the reductions in E. coli and fecal coliforms counts were less than two orders of magnitude. Based on the measurements of viable E. coli determined by the PMA-qPCR method, the microbial quality of digester effluents was discussed for agricultural application, and pasteurization after anaerobic digestion was suggested for the destruction of viable pathogens.
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Page, D. I., K. L. Hickey, R. Narula, A. L. Main i S. J. Grimberg. "Modeling anaerobic digestion of dairy manure using the IWA Anaerobic Digestion Model no. 1 (ADM1)". Water Science and Technology 58, nr 3 (1.08.2008): 689–95. http://dx.doi.org/10.2166/wst.2008.678.
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The Anaerobic Digestion Model No. 1 (ADM1) can be used to describe treatment of dairy manure once manure characteristics have been incorporated in the model. In this paper a parameter set is presented that can be used with ADM1 for simulation of dairy manure digester performance. Model results have been verified with bench-scale experiments and reported data from full-scale systems. Model predictions fit experimental data best for biogas composition and digester effluent COD. Simulated biogas productions were inconsistent with measurements from three different digesters. The model overpredicted acetogenesis, resulting in higher simulated than observed acetate concentrations. However, total volatile acid concentrations were simulated reasonably well. The model consistently predicted higher inorganic nitrogen than measured or reported results, indicating a need for further research in that area. The presented model and associated parameter set can be used to simulate and optimize the performance of full-scale dairy manure digesters.
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Méndez-Novelo, Roger Iván, Enrique Abraham Chan-Gutiérrez, Elba René Castillo-Borges, Elizabeth del Rosario Vázquez-Borges i Arturo Edgardo Espadas-Solís. "Digestión anaerobia de efluentes de fosas sépticas". Ingeniería, investigación y tecnología 13, nr 3 (1.07.2012): 339–49. http://dx.doi.org/10.22201/fi.25940732e.2012.13n3.032.
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Nguyen Vo Chau, Ngan, Thao Huynh Van, Thuan Nguyen Cong, Lavane Kim i Dan Van Pham. "Water lettuce (Pistia stratiotes L.) increases biogas effluent pollutant removal efficacy and proves a positive substrate for renewable energy production". PeerJ 11 (22.08.2023): e15879. http://dx.doi.org/10.7717/peerj.15879.
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Background Aquatic plants play a crucial role in nature-based wastewater treatment and provide a promising substrate for renewable energy production using anaerobic digestion (AD) technology. This study aimed to examine the contaminant removal from AD effluent by water lettuce (WL) and produce biogas from WL biomass co-digested with pig dung (PD) in a farm-scale biogas digester. Methods The first experiment used styrofoam boxes containing husbandry AD effluent. WLs were initially arranged in 50%, 25%, 12.5%, and 0% surface coverage. Each treatment was conducted in five replicates under natural conditions. In the second experiment, WL biomass was co-digested with PD into an existing anaerobic digester to examine biogas production on a farm scale. Results Over 30 days, the treatment efficiency of TSS, BOD5, COD, TKN, and TP in the effluent was 93.75–97.66%, 76.63–82.56%, 76.78–82.89%, 61.75–63.75%, and 89.00–89.57%, respectively. Higher WL coverage increased the pollutant elimination potential. The WL biomass doubled after 12 days for all treatments. In the farm-scale biogas production, the biogas yield varied between 190.6 and 292.9 L kg VSadded−1. The methane content reached over 54%. Conclusions WL removed AD effluent nutrients effectively through a phytoremediation system and generated significant biomass for renewable energy production in a farm-scale model.
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Sukias, J. P. S., i R. J. Craggs. "Digestion of wastewater pond microalgae and potential inhibition by alum and ammoniacal-N". Water Science and Technology 63, nr 5 (1.03.2011): 835–40. http://dx.doi.org/10.2166/wst.2011.101.
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Algae are produced in considerable quantities in oxidation ponds, and may negatively affect receiving waters when discharged at high concentration. Thus in some instances they require removal prior to effluent discharge, which may be enhanced using flocculants such as alum. Harvested algal biomass could be anaerobically digested to methane for use as a renewable energy source, however, alum, has been reported to inhibit anaerobic digestion. Psychrophilic (20°C) anaerobic digestion experiments showed a 13% reduction in methane production with 200 g m−3 alum in the flocculated algae, and a 40% reduction at an alum concentration of 1600 g m−3. Elevated ammoniacal-N concentrations (785 g NH4+−N m−3) also inhibited algal digestion at 20°C when using an inoculum of anaerobic bacteria from a mesophylic municipal wastewater sludge digester. However, anaerobic digestion using a bacterial inoculum from a psychrophilic piggery anaerobic pond (in which typical ammoniacal-N levels range between 200 and 2000 g NH4+−N m−3) were unaffected by elevated digester ammoniacal-N levels and methane production actually increased slightly at higher ammoniacal-N concentrations. Thus, selecting an anaerobic bacterial inoculum that is already adapted to high ammoniacal-N levels and the digestion temperature, such as that form an anaerobic pond treating piggery wastewater, may avoid ammonia inhibition of algal digestion.
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De Leén, C., i D. Jenkins. "Removal of fecal coliforms by thermophilic anaerobic digestion processes". Water Science and Technology 46, nr 10 (1.11.2002): 147–52. http://dx.doi.org/10.2166/wst.2002.0314.
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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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Vallini, G., F. Cecchi, P. Pavan, A. Pera, J. Mata-Alvarez i A. Bassettit. "Recovery and Disposal of the Organic Fraction of Municipal Solid Waste (MSW) by Means of Combined Anaerobic and Aerobic Bio-Treatments". Water Science and Technology 27, nr 2 (1.01.1993): 121–32. http://dx.doi.org/10.2166/wst.1993.0089.
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The paper deals with the semi-dry anaerobic digestion of municipal solid waste followed by composting as finishing treatment of the digested sludge. The integration of the anaerobic and aerobic treatments was studied as approach to close the water balance of the semi-dry anaerobic digestion process and to remove the phytotoxicity of the digested effluent. This study evaluated the response of the anaerobic effluent to the co-composting post-processing step, whether the anaerobic sludge came from mesophilic semi-dry digestion or thermophilic semi-dry nethanization. Evaluation of the strategy adopted was carried out in terms of performance of aerobic stabilization and its incidence on the economy of the overall treatment and the water balance of the process. Co-composting gave best results when integrated with thermophilic digestion.
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Journal, Baghdad Science. "Laser Improves Biogas Production by Anaerobic Digestion of Cow Dung". Baghdad Science Journal 15, nr 3 (13.09.2018): 324–27. http://dx.doi.org/10.21123/bsj.15.3.324-327.
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This study investigates the digestion of cow dung (CD) for biogas production at laboratory scales. The study was carried out through anaerobic fermentation using cow dung as substrate. The digester was operated at ambient temperatures of 39.5 °C for a period of 10 days. The effect of iron powder in controlling the production of hydrogen sulfide (H2S) has been tested. The optimum concentration of iron powder was 4g/L with the highest biogas production. A Q – swatch Nd:YAG laser has been used to mix and homogenize the components of one of the six digesters and accelerate digestion. At the end of digestion, all digestions effluent was subjected to 5 laser pulses with 250mJ/pules to dispose waste biomass.
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Vázquez-Padín, J. R., M. Figueroa, I. Fernández, A. Mosquera-Corral, J. L. Campos i R. Méndez. "Post-treatment of effluents from anaerobic digesters by the Anammox process". Water Science and Technology 60, nr 5 (1.05.2009): 1135–43. http://dx.doi.org/10.2166/wst.2009.421.
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The application of the Anammox process was studied under two different approaches for the post-treatment of anaerobic digester supernatants: two independent units, the combined SHARON-Anammox system, performed in a chemostate and a SBR, respectively, and, a single unit system composed by an air pulsing SBR to carry out the CANON process. The technology based on the combination of the SHARON-Anammox process was used to treat the effluent of an anaerobic digester from a fish canning industry. The presence of organic matter in the influent caused fluctuations in the efficiency of the SHARON unit and an optimal nitrite to ammonium ratio was not achieved in this system to feed the Anammox reactor. Nevertheless an overall percentage of nitrogen removal of 40–80% was obtained when the Anammox reactor operated at nitrite limited conditions. In those periods when the effluent from the SHARON unit contained a NO2−-N/NH4+-N molar ratio higher than 1.3 the Anammox process lost its stability due to nitrite accumulation. The effluent from an anaerobic digester placed at a WWTP was treated by a CANON system operated at room temperature (20–24°C). This system was developed from a nitrifying air pulsing reactor working at limiting dissolved oxygen conditions which was inoculated with Anammox biomass. A quick start-up of the system was observed and the reactor reached a nitrogen removal rate of 0.25 g N/(L d) 40 days after inoculation. The maximum nitrogen removal rate reached 0.5 g N/(L d). These results indicate the feasibility of the treatment of effluents from psychrophilic anaerobic digesters using the Anammox process.
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Elaiyaraju, P., i N. Partha. "Studies on biogas production by anaerobic process using agroindustrial wastes". Research in Agricultural Engineering 62, No. 2 (30.06.2016): 73–82. http://dx.doi.org/10.17221/65/2013-rae.
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This study investigated the effect of factors namely temperature, pH, substrate concentration on sago and tannery effluents by the anaerobic digestion process for biogas production. Response surface methodology with the Central Composite Design (CCD) experiments verified that the biogas production rates were mainly affected by operating temperature, pH, and substrate concentration. The experiments were carried out by two distinct effluents at different organic loading rate under mesophilic range of temperature 31–33°C. Co-digestion was carried out for a period of 21 days. The gas produced was measured by the liquid displacement system. Meanwhile, the highest biogas yields – 80% of CH<sub>4</sub> and 20% of CO<sub>2</sub> –produced in the combined effluent were confirmed by the Gas Chromatography (GC) analysis.
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Madondo, Nhlanganiso Ivan, Emmanuel Kweinor Tetteh, Sudesh Rathilal i Babatunde Femi Bakare. "Synergistic Effect of Magnetite and Bioelectrochemical Systems on Anaerobic Digestion". Bioengineering 8, nr 12 (30.11.2021): 198. http://dx.doi.org/10.3390/bioengineering8120198.
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Conventionally, the anaerobic digestion of industrial effluent to biogas constitutes less than 65% methane, which warrants its potential methanation to mitigate carbon dioxide and other anthropogenic gas emissions. The performance of the anaerobic digestion process can be enhanced by improving biochemical activities. The aim of this study was to examine the synergistic effect of the magnetite and bioelectrochemical systems (BES) on anaerobic digestion by comparing four digesters, namely a microbial fuel cell (MFC), microbial electrolysis cell (MEC), MEC with 1 g of magnetite nanoparticles (MECM), and a control digester with only sewage sludge (500 mL) and inoculum (300 mL). The MFC digester was equipped with zinc and copper electrodes including a 100 Ω resistor, whereas the MEC was supplied with 0.4 V on the electrodes. The MECM digester performed better as it improved microbial activity, increased the content of methane (by 43% compared to 41% of the control), and reduced contaminants (carbon oxygen demand, phosphates, colour, turbidity, total suspended solids, and total organic carbon) by more than 81.9%. Current density (jmax = 25.0 mA/m2) and electrical conductivity (275 µS/cm) were also high. The prospects of combining magnetite and bioelectrochemical systems seem very promising as they showed a great possibility for use in bioelectrochemical methane generation and wastewater treatment.
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van Haandel, Adrianus C. "Influence of the digested cod concentration on the alkalinity requirement in anaerobic digesters". Water Science and Technology 30, nr 8 (1.10.1994): 23–34. http://dx.doi.org/10.2166/wst.1994.0374.
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pH value and stability in anaerobic digesters are governed by the carbonic system. An expression is derived to determine the alkalinity requirement for maintaining a desired pH value in an anaerobic digester. The requirement is calculated from stoichiometric relationships and depends on measurable parameters of the influent (notably concentration of digestible material, influent VFA, alkalinity, acidity and organic nitrogen concentration) and operational conditions (temperature, recycle of effluent and/or biogas). The derived expression is applied to three cases of anaerobic digestion: dilute waste water (sewage), concentrated waste water (vinasse) and sludge. In each case it was calculated if the influent alkalinity was sufficient to maintain an adequate pH for digestion and when it was not, what was the alkalinity requirement to maintain the desired pH value. The calculated values of pH and alkalinity demand compared well with experimental data.
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Kraemer, Jeremy T., i David M. Bagley. "Simulation of the Impact of Higher Ammonia Recycle Loads Caused by Upgrading Anaerobic Sludge Digesters". Water Quality Research Journal 40, nr 4 (1.11.2005): 491–99. http://dx.doi.org/10.2166/wqrj.2005.053.
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Abstract Upgrading conventional single-stage mesophilic anaerobic digestion to an advanced digestion technology can increase sludge stability, reduce pathogen content, increase biogas production, and also increase ammonia concentrations recycled back to the liquid treatment train. Limited information is available to assess whether the higher ammonia recycle loads from an anaerobic sludge digestion upgrade would lead to higher discharge effluent ammonia concentrations. Biowin, a commercially available wastewater treatment plant simulation package, was used to predict the effects of anaerobic digestion upgrades on the liquid train performance, especially effluent ammonia concentrations. A factorial analysis indicated that the influent total Kjeldahl nitrogen (TKN) and influent alkalinity each had a 50-fold larger influence on the effluent NH3 concentration than either the ambient temperature, liquid train SRT or anaerobic digestion efficiency. Dynamic simulations indicated that the diurnal variation in effluent NH3 concentration was 9 times higher than the increase due to higher digester VSR. Higher recycle NH3 loads caused by upgrades to advanced digestion techniques can likely be adequately managed by scheduling dewatering to coincide with periods of low influent TKN load and ensuring sufficient alkalinity for nitrification.
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Britz, T. J., G. Spangenberg i C. A. Venter. "Acidogenic microbial species diversity in anaerobic digesters treating different substrates". Water Science and Technology 30, nr 12 (1.12.1994): 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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Ihara, Ikko, Kiyohiko Toyoda, Tsuneo Watanabe i Kazutaka Umetsu. "Nitrogen and energy balances of a combined anaerobic digestion and electrochemical oxidation process for dairy manure management". Australian Journal of Experimental Agriculture 48, nr 2 (2008): 208. http://dx.doi.org/10.1071/ea07254.
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Anaerobic digestion and electrochemical oxidation were investigated for their potential to recycle carbon and degrade nitrogen from dairy manure; the energy balance of this combination of treatments was also evaluated. Anaerobic digestion is a sustainable technology that allows recovery of biomass energy and treatment of animal wastes for carbon recycling. Since the anaerobic digestion process performs denitrification poorly, almost all nitrogenous substances are discharged in digested effluent as ammonia. The ammonium nitrogen in anaerobically digested effluent is degraded by electrochemical oxidation with an unsacrificial anode. The electrochemical oxidation requires inputs of electricity. We evaluated the feasibility of using electricity generated by a full-scale biogas plant, producing biogas from dairy manure, for the electrochemical oxidation of ammonium nitrogen in anaerobically digested effluent. Data on the amount of electricity generated by such a plant were compared with data on the electricity requirements of the electrochemical oxidation process to determine the energy balance of the two processes. The results indicated that electricity generated from a biogas plant was able to supply 24 to 33% of the electricity required for the electrochemical oxidation.
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Tilche, A., G. Bortone, G. Forner, M. Indulti, L. Stante i O. Tesini. "Combination of anaerobic digestion and denitrification in a hybrid upflow anaerobic filter integrated in a nutrient removal treatment plant". Water Science and Technology 30, nr 12 (1.12.1994): 405–14. http://dx.doi.org/10.2166/wst.1994.0640.
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A new nutrient removal plant configuration was designed and tested in pilot-scale for the treatment of piggery wastewater. The core of the process is represented by a Hybrid Upflow Anaerobic Filter where both anaerobic digestion and denitrification takes place. The pre-screened piggery wastewater is fed to the mesophilic anaerobic reactor. In the bottom of the sludge bed, anaerobic digestion and sulfate reduction are the prevalent processes. In the upper filter zone, a stream of nitrified clarified effluent is recycled and nitrates are denitrified utilizing the remaining available carbon and sulfides as electron donors. The anaerobic reactor should be slightly overloaded in order to provide VFAs for denitrification. The effluent of the anaerobic reactor is fed to the following P-removal stage, which is composed of a sludge pre-denitrification step, an anaerobic P-release step, an aerobic nitrification tank and a final settler. The pilot-plant treated 5 m3 d−1 of pre-screened piggery wastewater. The anaerobic digester (volume 15 m3) demonstrated it was to couple anaerobic digestion and denitrification. The overall plant removal efficiency was around 96% for COD, 92% for nitrogen and 92% for phosphorus. The anaerobic digester contributed 80% to the overall denitrification capacity.
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Augoustinos, M. T., T. J. Britz i R. P. Tracey. "Anaerobic digestion of a petrochemical effluent using an anaerobic hybrid digester". Biotechnology Letters 11, nr 5 (maj 1989): 369–74. http://dx.doi.org/10.1007/bf01024521.
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Eusébio, Ana, André Neves i Isabel Paula Marques. "Complementary Substrates-Brewery Wastewater and Piggery Effluent—Assessment and Microbial Community Profiling in a Hybrid Anaerobic Reactor". Applied Sciences 11, nr 10 (11.05.2021): 4364. http://dx.doi.org/10.3390/app11104364.
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A hybrid anaerobic reactor was operated under the complementary effluents concept to reduce the unbalanced/inhibitory capacity of the provided piggery effluent. Brewery wastewater was chosen to complement piggery effluent (60:40% v/v, respectively). The HRT reduction from 6.7 to 3.0 days allowed the testing of an organic load increase from 4.5 to 10.0 g COD/L·d, which resulted in the almost doubling of biogas production. Biogas volumes (1.2 and 2.1 L/L·d, respectively) associated with its quality (>77% CH4) revealed that the hybrid anaerobic reactor responded positively to the operational changes and that piggery effluent can be advantageously digested using the brewery wastewater as the complementary effluent. The unit bottom and the packing bed were the main functional sections recognized in the hybrid. At the beginning of anaerobic digestion, bacterial populations belonged mostly to Bacteroidales (33%) and Clostridiales (35%). The process stability and the biogas quality at 3-d HRT were related to a change in the structure composition, since Flavobacteriales (18%), Bacillales (7%), Pseudomonadales (11%) and members of the Alcaligenaceae family (5%) also integrated the microbial communities. An evident change had also occurred in archaeal populations at this phase. Methanosaeta became the dominant genus (95%), confirming that acetoclastic methanogenesis was the main way for methane production.
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Szelényi, Gábor Z., Róbert Kurdi, Nándor Nemestóthy, Katalin Bélafi-Bakó i Péter Bakonyi. "Managing the Effluents of Anaerobic Fermentations by Bioprocess Schemes Involving Membrane Bioreactors and Bio-Electrochemical Systems: A Mini-Review". Energies 15, nr 5 (23.02.2022): 1643. http://dx.doi.org/10.3390/en15051643.
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Anaerobic bioprocesses, such as anaerobic digestion and dark fermentation, provide energy carriers in the form of methane and hydrogen gases, respectively. However, their wastewater-type residues, that is, the fermentation effluents, must be treated carefully due to the incomplete and non-selective conversion of organic matter fed to the actual system. For these reasons, the effluents contain various secondary metabolites and unutilized substrate, in most cases. Only a fraction of anaerobic effluents can be directly applied for fertilization under a moderate climate. Conventional wastewater treatment technologies may be used to clean the remainder, but that approach leads to a net loss of energy and of potentially useful agricultural input materials (organic carbon and NPK fertilizer substitutes). The rationale of this paper is to provide an overview of promising new research results in anaerobic effluent management strategies as a part of technological downstream that could fit the concept of new-generation biorefinery schemes aiming towards zero-waste discharge, while keeping in mind environmental protection, as well as economical perspectives. According to the literature, the effluents of the two above processes can be treated and valorized relying either on membrane bioreactors (in case of anaerobic digestion) or bio-electrochemical apparatus (for dark fermentation). In this work, relevant findings in the literature will be reviewed and analyzed to demonstrate the possibilities, challenges, and useful technical suggestions for realizing enhanced anaerobic effluent management. Both membrane technology and bio-electrochemical systems have the potential to improve the quality of anaerobic effluents, either separately or in combination as an integrated system.
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ISMAIL, ISMAFATIN NABILAH, SHAHRUL ISMAIL i MOHAMED SHAHRIR MOHAMED ZAHARI. "MICROBIAL COMMUNITY PROFILING OF DIGESTED SLUDGE FROM PILOT PLANT BIO-DIGESTER". Universiti Malaysia Terengganu Journal of Undergraduate Research 3, nr 3 (31.07.2021): 53–60. http://dx.doi.org/10.46754/umtjur.v3i3.217.
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The production of biogas involves different microbial groups working in a synchronously and closely interactive manner. In Malaysia, biogas production from food waste is an encouraging alternative for sustainable energy production. Therefore, to better understand and optimize process, identification of the microbial community involved in anaerobic digestion (AD) is essential. The purpose of this study is to identify the microbial characteristics under different AD conditions to establish the links between microbial community structure and operational condition efficiency. The pilot plant bio-digester production performance will be determined by analysis of Chemical Oxygen Demand (COD) removal efficiency for 43 days. Next, when the performance of the digester has achieved an optimum level of removal efficiency, a sample of digested sludge will be taken for further analysis of microbial community profiling by undergo DNA extraction, amplifying DNA and Next Gene Sequencing (NGS) technology. The results show that the COD removal efficiency at an optimum level is 93%, while the percentage of methane gas composition inside the digester is 69%, indicating a very high efficiency for the digester. Thus, the lower the concentration of COD effluent, the higher the concentration of COD removal efficiency. Besides, an optimum an optimum level of COD removal efficiency indicates active microbial activities inside the bio-digester. Furthermore, the microbial community structure with operational conditions at various states of anaerobic digestion is summarizing. These findings are important as microbial characteristics of digested sludge is important to manage and optimize biogas production.
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Charles, W., N. P. Carnaje i R. Cord-Ruwisch. "Methane conversion efficiency as a simple control parameter for an anaerobic digester at high loading rates". Water Science and Technology 64, nr 2 (1.07.2011): 534–40. http://dx.doi.org/10.2166/wst.2011.082.
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The anaerobic digestion process is globally applied to the treatment of highly concentrated wastes such as industrial and rural effluents, and sewage sludge. However, it is known to be relatively unstable. When loaded with high concentrations of organic material, unwanted volatile fatty acids (VFA) are often produced rather than methane (CH4) gas which can lead to digester acidification and failure. This study investigated digester behaviour under high loading rates, testing the usefulness of stoichiometric methane conversion efficiency as a digester control parameter at high loading rates. Our results show that, in general, the CH4 production rate was proportional to the feed rate (loading rate). However, at very high loading rates, the CH4 production rate was not proportional to the increase in the feeding rate. Consequently, VFA accumulated and the H2 partial pressure increased. The proportionality of the loading rate and gas production rate is stoichiometrically expressed as the conversion efficiency. We found that conversion efficiency was a useful indicator as an early warning of digester imbalance. The digester remained stable at conversion efficiencies above 75%. Dropping below 70% signified the onset of digester failure. As loading rate and methane production data are readily available on-line in most anaerobic digestion plants, the conversion efficiency can be monitored on-line and used as an efficient control technique to maintain safe operation of anaerobic digesters at high loading rates.
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Usack, Joseph G., Wiratni Wiratni i Largus T. Angenent. "Improved Design of Anaerobic Digesters for Household Biogas Production in Indonesia: One Cow, One Digester, and One Hour of Cooking per Day". Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/318054.
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A government-sponsored initiative in Indonesia to design and implement low-cost anaerobic digestion systems resulted in 21 full-scale systems with the aim to satisfy the cooking fuel demands of rural households owning at least one cow. The full-scale design consisted of a 0.3 m diameter PVC pipe, which was operated as a conventional plug-flow system. The system generated enough methane to power a cooking stove for∼1 h. However, eventual clogging from solids accumulation inside the bioreactor proved to be a major drawback. Here, we improved the digester configuration to remedy clogging while maintaining system performance. Controlled experiments were performed using four 9-L laboratory-scale digesters operated at a temperature of27±1°C, a volatile solids loading rate of 2.0 g VS·L−1·day−1, and a 21-day hydraulic retention time. Two of the digesters were replicates of the original design (control digesters), while the other two digesters included internal mixing or effluent recycle (experimental digesters). The performance of each digester was compared based on methane yields, VS removal efficiencies, and steady-state solids concentrations during an operating period of 311 days. Statistical analyses revealed that internal mixing and effluent recycling resulted in reduced solids accumulation compared to the controls without diminishing methane yields or solids removal efficiencies.
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Girault, R., P. Rousseau, J. P. Steyer, N. Bernet i F. Béline. "Combination of batch experiments with continuous reactor data for ADM1 calibration: application to anaerobic digestion of pig slurry". Water Science and Technology 63, nr 11 (1.06.2011): 2575–82. http://dx.doi.org/10.2166/wst.2011.594.
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Modelling anaerobic digestion processes is a key aspect of studying and optimizing digesters and related waste streams. However, for the satisfactory prediction of biogas production and effluent characteristics, some parameters have to be calibrated according to the characteristics of the substrates. This article describes a calibration procedure for the IWA ‘Anaerobic Digestion Model no. 1’ applied to the modelling of a digester for treatment of pig slurry. The most sensitive parameters were selected and calibrated combining results from a continuous digester and from batch trials run with the sludge sampled from the digester and the addition of specific substrates. According to the sensitivity analysis, acetoclastic methanogenesis, acetogenesis of propionate and acidogenesis of sugars were identified as the main sensitive steps in our case. The calibration procedure led us to modify slightly acetogenesis of propionate kinetic. However, acetoclastic methanogenesis and acidogenesis of sugars kinetics were significantly reduced by decreasing km and increasing Ks. Indeed, for instance, a decrease of km_ac from 8 to 7 day−1 combined with an increase of Ks_ac from 0.15 to 1.5 kgCOD/m3 was necessary. After calibration, ADM1 provides an accurate simulation of the continuous reactor results.
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Stadterman, K. L., A. M. Sninsky, J. L. Sykora i W. Jakubowskii. "Removal and inactivation of cryptosporidium oocysts by activated sludge treatment and anaerobic digestion". Water Science and Technology 31, nr 5-6 (1.03.1995): 97–104. http://dx.doi.org/10.2166/wst.1995.0572.
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To determine the fate of Cryptosporidium parvum oocysts during wastewater treatment, a model of an activated sludge treatment plant was designed with a flow of 17 ml/min and a detention time of 6 hours. Samples of raw sewage were seeded with oocysts and primary and secondary effluents were analyzed for C. parvum using an immunofluorescent technique. To compare removal efficiencies of oocysts by various wastewater treatment processes, raw sewage, activated sludge, trickling filter and biodisc effluents were seeded with oocysts and settled for 2 hr and for the respective detention times. Sludge produced by a wastewater treatment plant and anaerobically digested at 37° C in a laboratory digester was also seeded with C. parvum oocysts. Oocyst inactivation was measured by excystation and direct counts. Removal of oocysts in primary and secondary sedimentation averaged 83.4% and 90.7% respectively. The total oocyst removal in sewage treatment averaged 98.6%. In comparison with other treatment processes, activated sludge had the maximum oocyst removal efficiency at 92%. The anaerobic digestion process inactivated 90% of the oocysts within four hours of exposure. 99.9% of the oocysts were eliminated by anaerobic digestion after 24 hours. This demonstrates that the activated sludge process and anaerobic digestion can be effective for the removal and inactivation of C. parvum oocysts.
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McCord, A. I., S. A. Stefanos, V. Tumwesige, D. Lsoto, M. Kawala, J. Mutebi, I. Nansubuga i R. A. Larson. "Anaerobic digestion in Uganda: risks and opportunities for integration of waste management and agricultural systems". Renewable Agriculture and Food Systems 35, nr 6 (11.10.2019): 678–87. http://dx.doi.org/10.1017/s1742170519000346.
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AbstractMuch of the global population lacks access to basic public sanitation, energy and fertilizers. Micro-scale anaerobic digestion presents an opportunity for low-cost decentralized waste management that creates valuable co-products of renewable energy and organic fertilizer. However, field-based assessments of system performance and clearly articulated guidelines for digestate management and field application are needed. Feedstocks and effluent from seven digesters in Kampala, Uganda were monitored for standard wastewater and fertilizer metrics including indicator organisms (Escherichia coli and fecal coliform), chemical oxygen demand (COD), biological oxygen demand (BOD5), total Kjeldahl nitrogen (TKN), total phosphorous (TP), heavy metals, pH, temperature and total solids (TS) over 2 yr. Results reveal that digester effluent does not meet standards for wastewater discharge or international safety standards for field application. Data indicate that digestate could be a suitable source of fertilizer (TKN = 1467 mg L−1, TP = 214 mg L−1) but poses issues for water quality if not managed properly (TS = 26,091 mg L−1, COD = 3471 mg L−1 and BOD5 = 246 mg L−1). While effluent from the digester contained pathogen indicator organisms (fecal coliform = 8.13 × 105 CFU/100 ml, E. coli = 3.27 × 105 CFU/100 ml), they were lower than the influent concentrations, and lower than reported concentrations in drainage canals. All digestate samples contained little to no heavy metals suggesting effective source separation. Data suggest that micro-scale biogas systems have potential to improve waste handling and meet standards associated with fertilizer application with proper post-digestion treatment.
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Folino, Adele, Demetrio Antonio Zema i Paolo S. Calabrò. "Environmental and Economic Sustainability of Swine Wastewater Treatments Using Ammonia Stripping and Anaerobic Digestion: A Short Review". Sustainability 12, nr 12 (18.06.2020): 4971. http://dx.doi.org/10.3390/su12124971.
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One of the most promising systems to treat swine wastewater is air stripping. This system simultaneously recovers nitrogen salts, to be used as fertiliser, and reduces the organic pollutant load in the effluents of swine breeding farms. Several reviews have discussed the air stripping as a treatment for many types of industrial wastewater or nitrogen-rich digestate (the liquid effluent derived from the anaerobic digestion plants) for the stripping/recovery of nutrients. However, reviews about the use of air stripping as treatment for raw or anaerobically digested swine wastewater are not available in literature. To fill this gap, this study: (i) Summarises the experiences of air stripping for recovery of ammonium salts from both raw and digested swine wastewater; and (ii) compares air stripping efficiency under different operational conditions. Moreover, combined systems including air stripping (such as struvite crystallisation, chemical precipitation, microwave radiation) have been compared. These comparisons have shown that air stripping of raw and digested swine wastewater fits well the concept of bio-refinery, because this system allows the sustainable management of the piggery effluent by extracting value-added compounds, by-products, and/or energy from wastewater. On the other hand, air stripping of raw and digested swine wastewater has not been extensively studied and more investigations should be carried out.
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Gutu, Larryngeai, Moses Basitere, Theo Harding, David Ikumi, Mahomet Njoya i Chris Gaszynski. "Multi-Integrated Systems for Treatment of Abattoir Wastewater: A Review". Water 13, nr 18 (7.09.2021): 2462. http://dx.doi.org/10.3390/w13182462.
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Biological wastewater treatment processes such as activated sludge and anaerobic digestion remain the most favorable when compared to processes such as chemical precipitation and ion exchange due to their cost-effectiveness, eco-friendliness, ease of operation, and low maintenance. Since Abattoir Wastewater (AWW) is characterized as having high organic content, anaerobic digestion is slow and inadequate for complete removal of all nutrients and organic matter when required to produce a high-quality effluent that satisfies discharge standards. Multi-integrated systems can be designed in which additional stages are added before the anaerobic digester (pre-treatment), as well as after the digester (post-treatment) for nutrient recovery and pathogen removal. This can aid the water treatment plant effluent to meet the discharge regulations imposed by the legislator and allow the possibility for reuse on-site. This review aims to provide information on the principles of anaerobic digestion, aeration pre-treatment technology using enzymes and a hybrid membrane bioreactor, describing their various roles in AWW treatment. Simultaneous nitrification and denitrification are essential to add after anaerobic digestion for nutrient recovery utilizing a single step process. Nutrient recovery has become more favorable than nutrient removal in wastewater treatment because it consumes less energy, making the process cost-effective. In addition, recovered nutrients can be used to make nutrient-based fertilizers, reducing the effects of eutrophication and land degradation. The downflow expanded granular bed reactor is also compared to other high-rate anaerobic reactors, such as the up-flow anaerobic sludge blanket (UASB) and the expanded granular sludge bed reactor (EGSB).
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Ross, W. R., J. P. Barnard, N. K. H. Strohwald, C. J. Grobler i J. Sanetra. "Practical Application of the ADUF Process to the Full-Scale Treatment of a Maize-Processing Effluent". Water Science and Technology 25, nr 10 (1.05.1992): 27–39. http://dx.doi.org/10.2166/wst.1992.0235.
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ADUFR (anaerobic digestion ultrafiltration) is a membrane-assisted process for positive separation of biomass from the treated effluent. Pilot and full-scale ADUFR studies were carried out on a maize-processing effluent (15 kgCOD/m3) at the Meyerton mill of Messrs. African Products, South Africa. The results after 15 months of full-scale operation have illustrated the merits of the process for the production of a colloid-free effluent at a mean COD removal efficiency of 97%. The permeate flux varied in the range 37 to 8 l.m−2.h−1 at 35°C, inlet pressure of 450 kPa, linear tube velocity of 1.6 m/s and digester suspended solids concentration of 21 kg/m3. Periodic chemical cleaning of the unsupported tubular polyethersulphone membranes with EDTA was only commenced after 13 months operation. A mean plant space load rate of 3 kgCOD.m−3.d−1 guaranteed reliability to withstand high COD shock loadings due to variations in the feed load. Bio-membrane separation technology of this nature holds important economic advantages for the treatment of a wide spectrum of organic industrial effluents.
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Kumar, Jha Ajay, Jian Zheng Li, Jun Guo He, Sheng Chang i A. K. Jha. "Optimization of Dry Anaerobic Fermentation of Solid Organic Wastes". Advanced Materials Research 113-116 (czerwiec 2010): 740–43. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.740.
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Dry methane fermentation is an innovative anaerobic digestion technique to treat solid bio-wastes without dilution for potential energy recovery with nutrient rich fertilizer and sustainable waste management. Although dry anaerobic fermentation offers great advantages like utilization of wastes in its produced form, high organic loading rate, no liquid effluent and comparable amount of biogas production with wet fermentation, commercial dry anaerobic digestion is scarcely used so far. In order to develop feasible dry fermentation process, it is important to review the optimization techniques and suggested possible areas where improvements could be made, including the reactor configuration, mixing, feed stocks, co-digestion, pretreatment and environmental conditions within the digester.
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Eusébio, Ana, André Neves i Isabel Paula Marques. "Structure of Microbial Communities When Complementary Effluents Are Anaerobically Digested". Applied Sciences 11, nr 3 (1.02.2021): 1293. http://dx.doi.org/10.3390/app11031293.
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Olive oil and pig productions are important industries in Portugal that generate large volumes of wastewater with high organic load and toxicity, raising environmental concerns. The principal objective of this study is to energetically valorize these organic effluents—piggery effluent and olive mill wastewater—through the anaerobic digestion to the biogas/methane production, by means of the effluent complementarity concept. Several mixtures of piggery effluent were tested, with an increasing percentage of olive mill wastewater. The best performance was obtained for samples of piggery effluent alone and in admixture with 30% of OMW, which provided the same volume of biogas (0.8 L, 70% CH4), 63/75% COD removal, and 434/489 L CH4/kg SVin, respectively. The validation of the process was assessed by molecular evaluation through Next Generation Sequencing (NGS) of the 16S rRNA gene. The structure of the microbial communities for both samples, throughout the anaerobic process, was characterized by the predominance of bacterial populations belonging to the phylum Firmicutes, mainly Clostridiales, with Bacteroidetes being the subdominant populations. Archaea populations belonging to the genus Methanosarcina became predominant throughout anaerobic digestion, confirming the formation of methane mainly from acetate, in line with the greatest removal of volatile fatty acids (VFAs) in these samples.
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Kovalev, Andrey A., Dmitriy A. Kovalev, Victor S. Grigoriev i Vladimir Panchenko. "Heat Recovery of Low-Grade Energy Sources in the System of Preparation of Biogas Plant Substrates". International Journal of Energy Optimization and Engineering 11, nr 1 (styczeń 2022): 1–17. http://dx.doi.org/10.4018/ijeoe.298693.
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Preliminary preparation of waste for anaerobic digestion at thermophilic temperature conditions is the most energy-intensive stage of the process of anaerobic bioconversion of production and consumption waste organic matter, therefore, the search for ways to reduce energy consumption at this stage remains an urgent task. The article proposes a technological solution to maintain the temperature regime of the digester operation due to the utilization of existing waste low-grade energy sources using a compression heat pump. The flow diagram of the experimental biogas plant is shown and a description of its operation is given. The dependences of the absolute and specific rates of heating of the influent and cooling of the effluent on the initial temperature of the effluent are given. The principal possibility of maintaining the temperature regime in the digester is shown by using the heat recovery of the effluent using a compression heat pump.
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Stergar, V., J. Zagorc-Končan i A. Zgajnar-Gotvanj. "Laboratory scale and pilot plant study on treatment of toxic wastewater from the petrochemical industry by UASB reactors". Water Science and Technology 48, nr 8 (1.11.2003): 97–102. http://dx.doi.org/10.2166/wst.2003.0457.
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This research concentrates on the development of an integrated approach to evaluate the possibility of treating very concentrated (COD = 15–20 g/l) and toxic wastewater (nitro-organic effluent) from the petrochemical industry in UASB reactors. A newly developed method utilising a modified Micro-Oxymax respirometer was used to (1) evaluate the inhibitory effects of varying concentrations of nitro-organic effluent on anaerobic granular sludge and (2) to make the proposal of operational parameters for the start up of the continuous process. Subsequently, the continuous tests were undertaken using laboratory scale upflow anaerobic sludge bed reactors to test gradual adaptation of anaerobic biomass to nitro-organic effluent. Practical application of the experimental results of the laboratory-scale continuous tests was evaluated by running the UASB pilot plant. Acceptable COD removal efficiencies were obtained when nitro-organic effluent was diluted with a readily biodegradable substrate up to 80 vol % of nitro-organic effluent in the inlet. The COD removal was 90% and the methane production rate was 4.5 l/d. Wastewater was detoxified and no acute toxicity of the treated wastewater to the anaerobic biomass was detected. This research indicates that anaerobic digestion of the undiluted nitro-organic effluent was not feasible. However, it is possible to blend the nitro-organic effluent with another effluent stream and co-treat these effluents.
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Loiacono, J., P. Pitt, D. Jenkins i T. Cockburn. "The Influence of Operating Experience on Wastewater Treatment Plant Design in San Francisco, California, USA". Water Science and Technology 25, nr 4-5 (1.02.1992): 257–64. http://dx.doi.org/10.2166/wst.1992.0503.
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Three main areas will be covered regarding the design and operation of a pure oxygen activated sludge plant. Air entrainment occurred in RAS and influent lines and gas entrainment occurred at the sixth stage effluent weirs in an enclosed pure oxygen aeration basin. This caused the oxygen feed to be shut off due to overpressurization and resulted in a combination of high apparent O2 usage and high vent gas purities. The use of an anaerobic selector for Nocardia control is discussed. Anaerobic digester operation has been adversely affected by Nocardia-dominated waste activated sludge. The effect of thick anaerobic digester foams on the ability to pump digested sludge is discussed.
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Ibrahim, A., B. G. Yeoh, S. C. Cheah, A. N. Ma, S. Ahmad, T. Y. Chew, R. Raj i M. J. A. Wahid. "Thermophilic Anaerobic Contact Digestion of Palm Oil Mill Effluent". Water Science and Technology 17, nr 2-3 (1.02.1985): 155–66. http://dx.doi.org/10.2166/wst.1985.0127.
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The palm oil industry is one of the major agro-based industries in Malaysia whose production accounts for more than 90% of the world export. The industry, however, also generates enormous quantities of liquid waste with high organic load causing serious pollution problems. In view of the high level of organics, anaerobic pretreatment is usually practised prior to aerobic breakdown. Most of the anaerobic digesters installed at the mills are currently operated under mesophilic conditions. However, the inherently high temperature of the effluent suggests that thermophilic digestion would bring about a much more effective system. This paper reports on results obtained from a pilot plant study on thermophilic anaerobic contact digestion of palm oil mill effluent which has been conducted and includes a microbiological study associated with the investigation.