Simultaneous synergistic efects of addition of agro‑based adsorbent on anaerobic co‑digestion of food waste and sewage sludge (original) (raw)
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Journal of Material Cycles and Waste Management, 2019
The aim of this study was to evaluate the performance of anaerobic co-digestion of food waste (FW) and sewage sludge (SS) at high organic load with the aid of an inorganic adsorbent supplementary. From BMP tests of seven mesophilic reactors, it was found that the stability of the system was hindered at higher organic load due to low alkalinity capacity of sludge (1600 mg/L) and excessive accumulation of inhibitory substances such as free ammonia and VFA. Thus, the low-cost adsorbent was applied to enhance the digestion process stability at high organic load (12.8 g VS/L). The results showed that addition of 1 g of sorghum-based activated carbon (SAC) (4 g TS/L) stabilized the system, reduced ammonia and T-VFA concentration from 267 to 39 mg/L, and 1300 to under 600 mg/L, respectively. Consequently, the methane yield increased from 201 to 272 mL/g VS (35%), solid retention time (SRT) reduced by 34%, and T-COD removal achieved by 79.38%. However, with a further increase of SAC the biogas generation decreased due to excessive adsorption of VFAs.
Bioresources and Bioprocessing, 2020
Multiple wastes’ co-digestion is one of the alternatives for improved anaerobic digestion (AD) process of industrial and municipal wastes. The present work investigated the influence of fruit–vegetable solid waste (FVW) addition as a co-substrate on the performance of AD of abattoir wastewater (AWW). The co-digestion was done at a lab-scale-based experiment under mesophilic condition using a two-phase anaerobic sequencing batch reactor without agitation. It was tested at different mixing ratios (100%AWW; 75%AWW:25%FVW; 50%AWW:50%FVW; 25%AWW:75%FVW; 100%FVW) with the intention of looking for the best mixing ratio with the best performance. It was fed on a semi-continuous basis and operated for 18 days (d) total retention time (HRT): 3 days for the acidogenesis reactor and 15 days for methanogenesis reactor. The addition of FVW enhanced biogas yield and VS removal by 70.26% and 57.11%, respectively, at optimum mixing ratio. Moreover, to some extent improvement of AD process stability ...
Synergistic effect from anaerobic co-digestion of sewage sludge and organic wastes
International Biodeterioration & Biodegradation, 2017
Anaerobic mono-digestion and co-digestion of primary sludge and two organic wastes (namely food waste or paper pulp reject) were evaluated by biomethane potential assessment and kinetics modelling to elucidate the synergistic effect. The specific methane yields were 159, 652 and 157 mL/g VS added during mono-digestion of primary sludge, food waste and paper pulp reject, respectively. Co-digestion of primary sludge with either food waste or paper pulp reject resulted in much higher specific methane yields of 799 and 368 mL/g VS, respectively. pH and intermediate inhibitions (e.g. volatile fatty acids and ammonium-N) were not observed. The synergistic effect was also confirmed by examining the VS and COD removals. COD balance also identified and validated the enhanced specific methane yields from both primary sludge and organic waste (i.e. additional 32 and 19% of COD was converted to biogas during codigestion of primary sludge with food waste or paper pulp reject, respectively). The apparent first order rate constant derived from kinetics modelling increased from 0.18 to 0.63 d À1 during mono-digestion of paper pulp reject and co-digestion of primary sludge with paper pulp reject, which can be attributed to the initial high soluble biodegradable fraction in primary sludge.
Waste Management, 2017
Due to low degradability of dry solids, most of the digesters at wastewater treatment plants (WWTP) operate at low loading rates resulting in poor biogas yields. In this study, co-digestion of sewage sludge (SS) with olive mill wastewater (OMW), cheese whey (CW) and crude glycerol (CG) was studied in an attempt to improve biogas production of existing digesters at WWTPs. The effect of agro-industrial byproducts in biogas production was investigated using a 220 L pilot-scale (180 L working volume) digester under mesophilic conditions (35°C) with a total feeding volume of 7.5 L daily and a 24-day hydraulic retention time. The initial feed was sewage sludge and the bioreactor was operated using this feed for 40 days. Each agro-industrial by-product was then added to the feed so that the reactor was fed continuously with 95% sewage sludge and 5% (v/v) of each examined agro-industrial by-product. The experiments showed that a 5% (v/v) addition of OMW, CG or CW to sewage sludge significantly increased biogas production by nearly 220%, 350% and 86% as values of 34.8 ± 3.2 L/d, 185.7 ± 15.3 L/d and 45.9 ± 3.6 L/d respectively, compared to that with sewage sludge alone (375 ml daily, 5% v/v in the feed). The average removal of dissolved chemical oxygen demand (d-COD) ranged between 72 and 99% for organic loading rates between 0.9 and 1.5 kg VS m À3 d À1. Reduction in the volatile solids ranged between 25 and 40%. This work suggests that methane can be produced very efficiently by adding a small concentration (5%) of agro-industrial by-products and especially CG in the inlet of digesters treating sewage sludge.
Environment, Development and Sustainability, 2020
An investigation on the efficiency and compatibility of anaerobic co-digestion of three substrates: food wastes (FW), chicken manure (CM) and digested sludge (DS) was carried out. Mixtures of two and three co-substrates in batch experiments were conducted in 0.5-L bioreactors during 8 days under mesophilic conditions. Parameters analysis such as pH, volatile fatty acids, free ammonia (NH 3), total solids (TS) and total volatile solids (TVS) was used to explain the behavior of each substrate and their mixtures. For the anaerobic digestion of two co-substrates (CM/DS with 30/70 ratio), total biogas production was equal to 2.5 L and was greater than the volume obtained for the same ratio of FW with DS. The three co-substrates (FW/CM/DS) digestion with (20/10/70) ratio showed best performances for total volatile solids (TVS) reduction and process stability. On the pilot bioreactor, a ratio of (20/5/75) was used for (FW/CM/DS) anaerobic digestion. After 50 days retention time, the biogas production reached 413.85 L/g TVS add with TS and TVS reduction of 79 and 87% respectively.
Trace elements play an indispensable role in stabilizing the performance of anaerobic co-digestion (Co-AD) of food waste (FW) and sewage sludge (SS) at greater organic load (OL). The results of high organic-loaded reactors showed that the stability of the system failed due to the buildup of volatile fatty acid (VFA) and ammonia. At the OL of 6.5 g/L, the stability of the system failed due to the buildup of propionic acid. The optimum dosage of Fe (5000 mg/L), Ni (200 mg/L), Zn (320 mg/L), and Mo (2.2 mg/L) was experimentally determined and added to reduce the inhibition condition. Consequently, the propionic acid concentration, which was above 1500 mg/L reduced to under 500 mg/L during Co-AD. Hence, higher biogas production, and biodegradability of 236 ± 23 mL/g VS, and 41.75%, respectively, were obtained. Increasing OL (9.5 g/L), the stability of the system was hindered due to only the buildup of ammonia (up to 188 ± 6 NH 3-N mg/L). Therefore, the trace elements of Cu (250 mg/L) and Co (3 mg/ L) were experimentally determined and added into the Co-AD to diminish ammonia accumulation and process instability. The experimental results showed that at OL of 14 g/L, biogas production, low ammonia concentration and biodegradability of 332 ± 21 mL/g VS, and 70 NH3-N mg/L, and 57.89%, respectively, were achieved. However, the performance and stability of the system failed at the higher OL due to the more increased ammonia and VFA concentration, and the greater dosages of trace elements did not enhance the process stability.
Anaerobic co-digestion of sewage sludge and food waste
Waste management & research : the journal of the International Solid Wastes and Public Cleansing Association, ISWA, 2016
Anaerobic co-digestion of organic matter improves digester operating characteristics and its performance. In the present work, food waste was collected from the institute cafeteria. Two types of sludge (before centrifuge and after centrifuge) were collected from the fluidised bed reactor of the institute treating sewage wastewater. Food waste and sludge were studied for their physico-chemical characteristics, such as pH, chemical oxygen demand, total solids, volatile solids, ammoniacal nitrogen, and total nitrogen. A biomethane potential assay was carried out to find out the optimum mixing ratio of food waste and sludge for anaerobic co-digestion. Results indicated that food waste mixed with sludge in the ratio of 1:2 produced the maximum biogas of 823 ml gVS(-1)(21 days) with an average methane content of 60%. Batch studies were conducted in 5 L lab-glass reactors at a mesophilic temperature. The effect of different substrate loading rates on biogas production was investigated. The...
2014
The overall goal of this research was to investigate the anaerobic co-digestion of municipal sewage sludge with selected organic wastes in three main areas: (1) to determine the maximum feasible loading of co-substrate, (2) to calibrate the ADM1 model for co-digestion system at steady state, and (3) to evaluate the linkage between microbial community dynamics and reactor performance and stability during steady state and overloading co-digestion. In this study, restaurant grease waste (GTW) as a commercial waste and biodiesel glycerin waste (BGW) as an industrial waste were co-digested with municipal wastewater sludge (MWS) in separate trials. In the first part of this research, the maximum feasible loading of each of the organic wastes with MWS with respect to the reactor performance and stability were investigated in the separate pilot-scale experiments. In each run, two 1300L completely mixed reactors were operated under mesophilic temperature (37°C) and a solids retention time (SRT) of 20 days. Throughout the pilot experiment, one reactor served as control and received only MWS and the other was assigned as the test digester and fed with the mixture of MWS and the co-substrate (GTW or BGW) in various organic loadings. GTW co-digestion with MWS was found to be feasible up to a maximum loading of 23% VS or 58% COD relative to the total 1.6 kg VS/m 3 •d or 4.0 kg COD/m 3 •d loadings, respectively. At this loading, test digester biogas production was 67% greater than that of the control. The test digester biogas production declined markedly when the percentage of VS from GTW in its feed was increased to 30% of its total VS loading. Causes of the reduced biogas production were investigated and attributed to process inhibition due to long chain fatty acid accumulation. The maximum safe limit of BGW co-digested with MWS was found at 23% and 35% of the total 1.04 kg VS/ (m 3 •d) and 2.38 kg COD/ (m 3 •d) loadings, respectively. At this loading, the biogas and methane production rates in the test digester were 1.65 and 1.83 times greater than of those in the control digester which received only MWS, respectively. Process instability was PREFACE This thesis is an original work by Vahid Razaviarani under supervision of Dr. Ian D. Buchanan. The anaerobic digester pilot plant referred to in Chapters 3 and 6, owned by the King County Wastewater Treatment Division, was housed in a trailer and located at the Gold Bar WWTP. The test facility contained a grinder tank, a feed tank, pumps, two 1300 L digesters, effluent tanks and other required utilities were provided in the trailer during the pilot scale study. The data analyses during the entire research and sample analyses are my original work, as well as the literature review in Chapter 1. Chapter 3 of this thesis has been published as an original research article of V. Razaviarani, I. Buchanan, S. Malik, H. Katalambula entitled "Pilot-scale anaerobic co-digestion of municipal wastewater sludge with restaurant grease trap waste", Journal of Environmental Management, 123, 26-33. I was responsible for the lab measurements, data collection and analyses for the manuscript composition. Chapter 6 of this thesis has been published as an original research article of V. Razaviarani, I. Buchanan, S. Malik, H. Katalambula entitled "Pilot-scale anaerobic co-digestion of municipal wastewater sludge with biodiesel glycerin waste", Bioresource Technology, 133, 206-212. I was responsible for the lab measurements, data collection and analyses for the manuscript composition. The bench-scale setup referred to in Chapters 4, 5 and 7 were designed by myself, with the assistance of Christine Heyregers. I was responsible for the reactor operation, data collection and analysis, and experimental measurements throughout the bench-scale study. v DEDICATION This dissertation is dedicated to my beloved family for their love, endless support and encouragement. My mother who taught me that even the largest task can be accomplished if it is done one step at a time, and my father who taught me that the best kind of knowledge to have is that which is learned for its own sake. I also dedicate this thesis to my only brother, Farid, who has never left my side and is very special. vi ACKNOWLEDGEMENTS I would like to sincerely express my appreciation to my supervisor, Dr. Ian D. Buchanan for his continual support and guidance through my PhD study. His
Bioresource Technology Reports, 2021
In this study, the anaerobic co-digestion of food waste (FW) and sewage sludge (SS) was investigated for the production of hydrogen and volatile fatty acids (VFAs). The results showed that the anaerobic codigestion of these materials enhanced the hydrogen content by 62.4% (v/v), 29.89% higher than that obtained by FW digestion alone, and the total VFA production reached at 281.84 mg/g volatile solid (VS), a 8.38% increase. This enhancement was primarily resulted from improvements in the multisubstrate characteristics, which were obtained by supplying a higher soluble chemical oxygen demand (23.78-32.14 g/L) and suitable a pH (6.12-6.51), decreasing total ammonia nitrogen by 18.67% and ensuring a proper carbon/nitrogen ratio (15.01-23.01). Furthermore, maximal hydrogen (62.39 mL/g VS) and total VFA production potential (294.63 mg/g VS) were estimated using response surface methodology optimization, which yielded FW percentages of 85.17% and 79.87%, respectively. Based on a pyrosequencing analysis, the dominant bacteria associated with VFA and hydrogen production were promoted under optimized condition, including members of genera Veillonella and Clostridium and the orders Bacteroidales and Lactobacillales.