Nitrogen Inhibition during an anaerobic co-digestion process was studied in this work.The substrate and inoculum used were obtained from a thermophilic biogas plant Sobacken,situated in Borås, Sweden. The batch experiments have been carried out in triplicate reactorswith different concentrations of ammonia ranging from 2400mg/l to 3400mg/l. The batchexperiment was working well for the all the concentrations of ammonia investigated. Theaverage methane yield was around 0.65 Nm3 CH4/kgVS for all the reactors. The laboratorywork has been further proceeded with a continuous process having two reactors working inparallel. Reactor 1 containing only substrate and the Reactor 2 contain substrate with surplusammonia added to make final concentration of 3400mg/l. The reactors were operated atorganic loading rate (OLR) of 3.3gVS/l/day and hydraulic retention time (HRT) of 20 days.Both reactors worked well for 29 days. During a period of an initial stable operation, theaverage methane production of Reactor 1 was 0.59 Nm3CH4/kgVS/day and for Reactor 2 theproduction rate was 0.56 Nm3CH4/kgVS/day. Then Reactor 1 showed a steady decrease in pHand methane production, while Reactor 2 showed stable operation for a few days longer withdecreasing pH and methane production only from day 36. The composition of substrate wasnot optimal; therefore the inhibition level of ammonium could not be determined.

Made available in DSpace on 2017-07-10T15:14:38Z (GMT). No. of bitstreams: 1 Claudinei.pdf: 2960967 bytes, checksum: 9d19185b777a99f89f11718066e20baa (MD5) Previous issue date: 2016-04-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The use of alternative energy sources is driven by the aim of minimizing environmental degradation in order to avoid that natural resources are depleted and slow the advance of global warming caused by emissions of greenhouse gases. Much has been researched about new energy sources, among which may be cited as the main: solar energy, wind energy, hydropower and biomass. The biogas from the biological treatment is distinguished by its increasing use to be a source of clean energy with a great social, financial and environmental return to humanity. To enhance this production of biogas, area researchers see performing various combinations, to evaluate or how best to combine any type of waste and succeed in increasing biogas production, consequently use in the energy sector. Thus, this work presents the objective analysis of the Total Solids removal rate, using the APHA methodology, 2012; Analysis of Higher Calorific Value using calorimeter; Analyze Biogas composition, by a Gas Chromatograph and analysis of biogas production using swine manure, silage medium grain corn, sorghum and pasture ground ruziziensis following a Factorial Planning 23, resulting in higher cumulative production to combination of swine wastewater 90% + Brachiária ruziziensis 10%, with 37.2 liters of biogas in seven weeks. Analyzing - the potential production per kilogram of matter, the highest result was the combination of ARS (80%) + Silage corn (10%) + Brachiária (10%), with 22 L.kg-1. Upon analyzing the result of production per kilogram of total solids, the result of the combination is greater production ARS (90%) + Brachiaria (10%), with approximately 561 L.Kg ST-1. / A utilização de fontes alternativas de energia é impulsionada pelo intuito de minimizar a degradação ambiental de forma a evitar que os recursos naturais se esgotem e diminuir o avanço do aquecimento global causado pelas emissões dos gases de efeito estufa. Muito se tem pesquisado a respeito de novas fontes energéticas, dentre elas podem ser citadas como principais: energia solar, energia eólica, energia hídrica e biomassa. O biogás, proveniente do tratamento biológico, se destaca pelo seu uso crescente por ser uma fonte de energia limpa com um grande retorno social, financeiro e ambiental para humanidade. Para potencializar essa produção de biogás, pesquisadores da área veem realizando diversas combinações, para avaliar qual ou quais as melhores formas de combinar algum tipo de resíduo e obter sucesso no aumento da produção de biogás, consequentemente utilização no setor energético. Desta forma, este trabalho apresenta por objetivo analise da taxa de remoção de Sólidos Totais, utilizando a metodologia de APHA, 2012; Análise de Poder Calorífico Superior, utilizando Calorímetro; Analise de Composição do Biogás, por meio de um Cromatógrafo Gasoso e analise da produção de biogás utilizando dejeto suíno, silagem de milho de meio grão, sorgo sacarino e braquiária Ruziziensis triturados, seguindo um Planejamento Fatorial 23, tendo como resultado de maior produção acumulada à combinação de Água Residuária de Suinocultura 90% + Braquiária Ruziziensis 10%, com 37,2 litros de biogás em sete semanas. Analisando se o potencial de produção por quilo de matéria, o maior resultado foi à combinação de ARS (80%) + Silagem Milho (10%) + Braquiária (10%), com 22 L.kg-1. Ao ser analisado o resultado de produção por quilo de Sólidos Totais, o resultado de maior produção é na combinação ARS (90%) + Braquiária (10%), com aproximadamente 561 L.Kg-1 ST.

This study aimed at seeking for the solution to recover the energy from agriculture waste in the Mekong Delta, Vietnam. The spent mushroom compost - a residue from the mushroom growing - was chosen for co-digestion with pig manure in anaerobic batch and semi-continuous experiments. The results showed that in case of spent mushroom compost made up 75% of the mixed substrate, the gained biogas volume was not significantly different compared to the treatment fed solely with 100% pig manure. The average produced biogas was 4.1 L×day-1 in the experimental conditions. The semi-continuous experiments remained in good operation up to the 90th day of the fermentation without any special agitating method application. The methane contents in both experiments were around 60%, which was significantly suitable for energy purposes. These results confirm that spent mushroom compost is possibly an acceptable material for energy recovery in the anaerobic fermentation process. / Nghiên cứu này nhằm tìm kiếm giải pháp thu hồi năng lượng từ chất thải nông nghiệp tại ĐBSCL, Việt Nam. Rơm sau ủ nấm - phế phẩm sau khi trồng nấm rơm - được chọn để ủ kết hợp với phân heo trong các bộ ủ yếm khí theo mẻ và bán liên tục. Kết quả cho thấy nếu phối trộn đến 75% rơm sau ủ nấm trong nguyên liệu ủ, tổng lượng khí thu được không khác biệt đáng kể so với thí nghiệm ủ 100% phân heo. Trong điều kiện thí nghiệm, lượng khí thu được trung bình là 4.1 L.ngày-1. Thí nghiệm ủ bán liên tục vẫn vận hành tốt ở ngày thứ 90 mặc dù mẻ ủ không được khuấy đảo. Hàm lượng khí mê-tan đo được chiếm khoảng 60% hoàn toàn có thể sử dụng cho các nhu cầu về năng lượng. Những kết quả thí nghiệm khẳng định có thể sử dụng rơm sau ủ nấm để thu hồi năng lượng thông qua quá trình ủ yếm khí kết hợp.

The main objective of this thesis was to study the anaerobic digestion (AD) of wastewater from a chicken processing facility and of crude glycerol from local biodiesel operations. The AD of these substrates was conducted in bench-scale reactors operated in the batch mode at 35°C. The secondary objective was to evaluate two sources of glycerol as co-substrates for AD to determine if different processing methods for the glycerol had an effect on CH₄ production. The biogas yields were higher for co-digestion than for digestion of wastewater alone, with average yields at 1 atmosphere and 0°C of 0.555 and 0.540 L (g VS added)⁻¹, respectively. Another set of results showed that the glycerol from an on-farm biodiesel operation had a CH₄ yield of 0.702 L (g VS added)⁻¹, and the glycerol from an industrial/commercial biodiesel operation had a CH₄ yield of 0.375 L (g VS added)⁻¹. Therefore, the farm glycerol likely had more carbon content than industrial glycerol. It was believed that the farm glycerol had more impurities, such as free fatty acids, biodiesel and methanol. In conclusion, anaerobic co-digestion of chicken processing wastewater and crude glycerol was successfully applied to produce biogas rich in CH₄.

Fat, oil, and grease residues, food particles, solids and some kitchen wastewaters are collected in grease traps which are separate from the municipal wastewater stream. Grease traps are emptied periodically and grease trap waste (GTW) is hauled for treatment. This dissertation focuses on anaerobic co-digestion of un-dewatered (raw) GTW with municipal wastewater treatment sludge (MWS) at wastewater treatment plants. In particular, this research focuses on the biochemical methane potential of un-dewatered GTW as well as the stability and performance of anaerobic co-digestion of MWS and un-dewatered GTW. A set of modified biochemical methane potential tests was performed to determine the methane potential of un-dewatered GTW under mesophilic conditions (35 °C). Methane potential of un-dewatered GTW in this study was 606 mL CH₄/g VS [subscript added] which is less than previously reported methane potentials of 845 - 1050 mL CH₄/g VS [subscript added] for concentrated/dewatered GTW. However, the methane potential of un-dewatered GTW (606 mL CH₄/g VS [subscript added]) was more than two times greater than the 223 mL CH₄/g VS [subscript added] reported for MWS digestion alone. A comprehensive study was performed to determine the stability and performance of anaerobic co-digestion of MWS with un-dewatered GTW as a function of increasing GTW feed ratios. The performance of two semi-continuously fed anaerobic digesters at 35 °C was evaluated as a function of increasing GTW feed ratios. Anaerobic co-digestion of MWS with un-dewatered GTW at a 46% GTW feed ratio (on a volatile solids basis) resulted in a 67% increase in methane production and a 26% increase in volatile solids reduction compared to anaerobic digestion of MWS alone. On the other hand, anaerobic co-digestion of un-dewatered GTW resulted in a higher inhibition threshold (46% on VS basis) than that of dewatered GTW. These results indicate that using un-dewatered GTW instead of dewatered GTW can reduce the inhibition risk of anaerobic co-digestion of MWS and GTW. Recovery of the anaerobic digesters following upset conditions was also evaluated and semi-continuous feed of digester effluent into upset digesters yielded of the biogas production level of the undisrupted digestion. Finally, a mathematical model was used to describe the relationship between methane potential and GTW feed ratio on a VS basis. The results of this research can be used to predict methane production and identify suitable GTW feeding ratios for successful co-digestion of un-dewatered GTW and MWS. / text

In this project, by adding selected co-substrates and by incorporating optimum pre-treatment strategies, four experimental phases were conducted to assess the enhancement of biogas production from anaerobic co-digestion using wastewater treatment plant sludge as the primary substrate. In the first phase, the feasibility of using municipal organic wastes (synthetic kitchen waste (KW) and fat, oil and grease (FOG)) as co-substrates in anaerobic co-digestion was investigated. KW and FOG positively affected biogas production from anaerobic co-digestion, with ideal estimated substrate/inoculum (S/I) ratio ranges of 0.80-1.26 and 0.25-0.75, respectively. Combined linear and non-linear regression models were employed to represent the entire digestion process and demonstrated that FOG could be suggested as the preferred co-substrate. The effects of ultrasonic and thermo-chemical pre-treatments on the biogas production of anaerobic co-digestion with KW or FOG were investigated in the second phase. Non-linear regressions fitted to the data indicated that thermo-chemical pre-treatment could increase methane production yields from both FOG and KW co-digestion. Thermo-chemical pre-treatments of pH=10, 55°C provided the best conditions to increase methane production from FOG co-digestions. In the third phase, using the results obtained previously, anaerobic co-digestions with FOG were tested in bench-scale semi-continuous flow digesters at Ravensview Water Pollution Control Plant, Kingston, ON. The effects of hydraulic retention time (HRT), organic loading rate (OLR) and digestion temperature (37°C and 55°C) on biogas production were evaluated. The best biogas production rate of 17.4±0.86 L/d and methane content 67.9±1.46% was obtained with thermophilic (55°C) co-digestion at HRT=24 days and OLR=2.43±0.15 g TVS/L•d. In the fourth phase, with the suitable co-substrate, optimum pre-treatment method and operational parameters identified from the previous phases, anaerobic co-digestions with FOG were investigated in a two-stage thermophilic semi-continuous flow co-digestion system modified to incorporate thermo-chemical pre-treatment of pH=10 at 55°C. Overall, the modified two-stage co-digestion system yielded a 25.14±2.14 L/d (with 70.2±1.4% CH4) biogas production, which was higher than that obtained in the two-stage system without pre-treatment. The positive results could provide valuable information and original contribution to justify full-scale investigation in a continuing research program and to the field of research on anaerobic co-digestion of municipal organic wastes. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-09-20 09:00:09.719

The application of anaerobic digestion (AD) as a sustainable waste management technology is growing worldwide, due to high energy prices as well as increasingly strict environmental regulations. The growth of the AD industry necessitates exploring new substrates for their utilisation in AD processes. The present work investigates the AD of two recalcitrant biomass: lignocelluloses and keratin-rich residues. The complex nature of these waste streams limits their biological degradation; therefore, suitable pre-processing is required prior to the AD process.In the first part of the study, the effects of organic solvent pre-treatments on bioconversion of lignocelluloses (straw and forest residues) to biogas were evaluated. Pre-treatment with N-methylmorpholine-N-oxide (NMMO) resulted in minor changes in the composition of the substrates, while their digestibility significantly increased. Furthermore, due to the high cost of the NNMO, the effect of pre-treatment with the recycled solvent was also explored. Since it was found that the presence of small traces of NMMO in the system after the treatment has inhibitory effects on AD, pre-treatments of forest residues using other organic solvents, i.e. acetic acid, ethanol, and methanol, were investigated too. Although pre-treatments with acetic acid and ethanol led to the highest methane yields, the techno-economical evaluation of the process showed that pre-treatment with methanol was the most viable economically, primarily due to the lower cost of methanol, compared to that of the other solvents.In the second part of the work, wool textile wastes were subjected to biogas production. Wool is mainly composed of keratin, an extremely strong and resistible structural protein. Thermal, enzymatic and combined treatments were, therefore, performed to enhance the methane yield. The soluble protein content of the pre-treated samples showed that combined thermal and enzymatic treatments had significantly positive effects on wool degradation, resulting in the highest methane yields, i.e. 10–20-fold higher methane production, compared to that obtained from the untreated samples.In the last part of this thesis work, dry digestion of wheat straw and wool textile waste, as well as their co-digestion were studied. The total solid (TS) contents applied in the digesters were between 6–30% during the investigations. The volumetric methane productivity was significantly enhanced when the TS was increased from 6 to 13–21%. This can be a beneficial factor when considering the economic feasibility of large-scale dry AD processes.

In this thesis, the anaerobic co-digestion of thickened waste activated sludge (TWAS) and, fat, oil and grease (FOG) was investigated as a method for TWAS:FOG treatment, stabilization, reduction and conversion to bio-methane gas as a valuable source of renewable energy. In the first phase, thermophilic and hyper-thermophilic anaerobic co-digestion of TWAS and FOG were investigated and compared. 20 – 80%FOG (based on total volatile solids) were tested using two sets of biochemical methane potential assays (BMP). Hyper-thermophilic co-digestion of TWAS with up to 60%FOG was shown to significantly increase the methane production and VS reduction as compared to the thermophilic co-digestion of the same TWAS:FOG mixture and as compared to the control (TWAS thermophilic mono-digestion). Both linear and non-linear regression models were used to represent the co-digestion results. In the second phase, the feasibility of the thermophilic and hyper-thermophilic co-digestion of TWAS and FOG were more investigated using lab scale semi-continuous reactors. The dual stage hyper-thermophilic reactor was introduced for the first time in this work for co-digesting TWAS and FOG. The dual stage co-digestion reactor was shown to significantly outperform the single-stage thermophilic mono-digestion reactor (the control) and the single-stage thermophilic co-digestion reactor at all three hydraulic retention times (HRTs) considered in the study namely, 15, 12 and 9 days. The dual-stage hyper-thermophilic co-digester digested up to 70%FOG at 15 days HRT without any stressing signs and produced a methane yield that was 148.2% higher compared to the control methane yield at the same HRT. It also produced a class A effluent at all three tested HRTs and positive net energy for 15 and 12 days HRT. The effects of microwave (MW) pretreatment, and combined alkaline-MW pretreatment on the co-digestion of TWAS:FOG mixtures with 20, 40 and 60% FOG were investigated in the third phase of this study. MW pretreatment at a high temperature of 175ᵒC was shown to be the most effective MW pretreatment option in solubilizing TWAS:FOG mixtures and in boosting the methane yield. It resulted in maximum solubilization for the 20%FOG samples and maximum methane yield for samples with 60%FOG. The combined alkaline-MW (NaOH-MW) pretreatment at a pH 10 showed to be an ineffective option for TWAS:FOG pretreatment before the anaerobic co-digestion process. In the fourth phase, the effects of the three selected pretreatments on the solubilization of TWAS and 20%FOG mixture on the molecular scale were investigated. The pretreatments used included: (i) MW pretreatment at 175ᵒC (since this was the best MW pretreatment condition according to the results of phase 3), (ii) hyper-thermophilic stage @ 70ᵒC and 2days HRT (effectively used in phases 1 and 2), and (iii) conventional heat at 70ᵒC. The analysis involved separation of the solubilized substrates after pretreatment using ultrafiltration (UF) at four different sizes (1, 10, 100 and 300 kDa). The results showed that each pretreatment method uniquely changed the particle size distribution. These changes showed to affect the biodegradability of substrates with different class size. Finally, two brief studies were performed using BMP tests to investigate the feasibility of FOG addition as a biogas booster in TWAS anaerobic digestion. First, the effect of FOG addition on TWAS and organic fraction of municipal solid waste (OFMSW) co-digestion was tested using hyper-thermophilic BMP tests. The addition of 30% FOG (based on total volatile solids) was shown very effective in improving the methane yield. The 30% FOG addition to TWAS:OFMSW mixture resulted in 59.9 and 84.4% higher methane yield compared to the methane yields of TWAS:OFMSW and TWAS samples, respectively. Second, the feasibility of using the soluble part of FOG (L-FOG) as a co-digestion substrate to increase the biogas production from the thermophilic digestion of TWAS was investigated. The results showed that co-digestion of TWAS and 20 to 80% (based on total VS) of L-FOG using a substrate to inoculum ratio (S/I) of 1 improved the biogas yield by 13.5 to 83.0%, respectively. No inhibition was reported at high L-FOG %.

abstract: Seeking to address sustainability issues associated with food waste (FW), and fat, oil, and grease (FOG) waste disposal, the City of Mesa commissioned the Biodesign Swette Center for Environmental Biotechnology (BSCEB) at Arizona State University (ASU) to study to the impact of implementing FW/FOG co-digestion at the wastewater treatment plant (WWTP). A key issue for the study was the “souring” of the anaerobic digesters (ADs), which means that the microorganism responsible for organic degradation were deactivated, causing failure of the AD. Several bench-scale reactors soured after the introduction of the FW/FOG feed streams. By comparing measurements from stable with measurements from the souring reactors, I identified two different circumstances responsible for souring events. One set of reactors soured rapidly after the introduction of FW/FOG due to the digester’s hydraulic retention times (HRT) becoming too short for stable operation. A second set of reactors soured after a long period of stability due to steady accumulation of fatty acids (FAs) that depleted bicarbonate alkalinity. FA accumulation was caused by the incomplete hydrolysis/fermentation of feedstock protein, leading to insufficient release of ammonium (NH4+). In contrast, carbohydrates were more rapidly hydrolyzed and fermented to FAs. The most important contribution of my research is that I identified several leading indicators of souring. In all cases of souring, the accumulation of soluble chemical oxygen demand (SCOD) was an early and easily quantified indicator. A shift in effluent FA concentrations from shorter to longer species also portended souring. A reduction in the yield of methane (CH4) per mass of volatile suspended solids removed (VSSR) also identified souring conditions, but its variability prevented the methane yield from providing advanced warning to allow intervention. For the rapidly soured reactors, reduced bicarbonate alkalinity was the most useful warning sign, and an increasing ratio of SCOD to bicarbonate alkalinity was the clearest sign of souring. Because I buffered the slow-souring reactors with calcium carbonate (CaCO3), I could not rely on bicarbonate alkalinity as an indicator, which put a premium on SCOD as the early warning. I implemented two buffering regimes and demonstrated that early and consistent buffering could lead to reactor recovery. / Dissertation/Thesis / Masters Thesis East Asian Languages and Civilizations 2020

In order to decrease the pollution of the marine environment from dumping fish waste and by-catch, alternative use for co-digestion with sludge in anaerobic condition was studied. The purpose of this project is to optimize the methane potential from adjustment of the proportion among mixed substrates. Ten groups of different proportions among fish waste, by-catch and sludge were conducted with AMPTS II instrument under mesophilic condition (37 ± 0.5 ºC), by means of the principle of BMP test. The ratio of inoculums and mixed substrate was set as 3:2. The optimal MP obtained after an experiment with 13 days digestion was 0.533 Nm3 CH4/kg VS from the composition of sludge, by-catch and fish waste as 33 %, 45 % and 22 %. It was improved by 6 % and 25.6 %, to compare with the previous studies by Almkvist (2012) and Tomczak-Wandzel (personal communication, February 2012) respectively.