Journal articles: 'Anaerobic hydrolysis'

1

Johansen, J. E., and R. Bakke. "Enhancing hydrolysis with microaeration." Water Science and Technology 53, no. 8 (April 1, 2006): 43–50. http://dx.doi.org/10.2166/wst.2006.234.

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Effects of microaeration on hydrolysis of primary sludge are investigated in 500 ml batch reactors at 377 °C. Two experiments, one with a microaerobic inoculum and one with a combination of a microaerobic and an anaerobic inoculum, are carried out to also investigate the role of the inoculum. Assuming an acidogenic, methanogenic and aerobic biomass yield of 0.1, 0.05 and 0.45 mgC/mgC, respectively, a 50–60% hydrolysis increase, during the 4 day experiment, is observed with a ratio between aerobic and anaerobic metabolism in the range 0.5–0.7. The extra hydrolysed products are oxidized to carbon dioxide and incorporated into new biomass. The oxygen utilization to carbon dioxide production ratio was ∼1:1 on a mol basis. Effects of the oxygen supplied on the hydrolysis of carbohydrates, proteins and lipids are analyzed based on measurements and balances of dissolved carbon, nitrogen and COD. The total observed hydrolysis increase can be accounted for by increased hydrolysis of carbohydrates and proteins. Lipids are only hydrolysed when anaerobic inoculum is added, but no effect of oxygen availability is detected.

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Cassini, S. T., M. C. E. Andrade, T. A. Abreu, R. Keller, and R. F. Gonçalves. "Alkaline and acid hydrolytic processes in aerobic and anaerobic sludges: effect on total EPS and fractions." Water Science and Technology 53, no. 8 (April 1, 2006): 51–58. http://dx.doi.org/10.2166/wst.2006.235.

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Sludge samples from an upflow anaerobic sludge blanket (UASB) reactor and four submerged aerated biofilters (BFs) of a wastewater treatment plant (1,000 inhab.) were processed at bench scale by alkaline and acid hydrolysis with the objective to evaluate the organic matter solubilization, volatile solids (VS) destruction and the effect of hydrolytic processes on the extracellular polymeric substances (EPS) fraction of the sludge samples. The results showed that alkaline hydrolysis of sludge samples treatment with 1.0% total solids (TS) using NaOH 20 meq L−1 was more efficient on organic matter solubilization and VS destruction than acid hydrolysis. The EPS sludge content was also affected by the alkaline treatment of anaerobic sludge samples. The EPS concentrations (mg EPS/gVSS) on the anaerobic sludge after the alkaline treatment were significantly lowered according to sample height in the UASB reactor. Data indicated that the EPS sludge fraction is the main component affected by the alkaline hydrolytic process of anaerobic sludge samples.

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Goel, Rajeev, Takashi Mino, Hiroyasu Satoh, and Tomonori Matsuo. "Comparison of hydrolytic enzyme systems in pure culture and activated sludge under different electron acceptor conditions." Water Science and Technology 37, no. 4-5 (February 1, 1998): 335–43. http://dx.doi.org/10.2166/wst.1998.0659.

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Enzymatic hydrolysis under different electron acceptor conditions in nutrient removal activated sludge treatment processes is a weak link in the Activated Sludge Model no. 2 (Henze et al., 1995). An experimental study was undertaken to gain insight into the hydrolysis process with specific focus on hydrolysis kinetics and rates under different electron acceptor conditions. Two pure cultures, Bacillus amyloliquefaciens (Gram positive) and Pseudomonas saccharophila (Gram negative) were chosen for the study. In addition, activated sludge grown in an anaerobic-aerobic system was tested for enzymatic activity using starch as the model substrate. The hydrolytic enzymes were found to be released into the bulk in pure cultures whereas the enzyme activity was found to be mainly associated with the cell surfaces in activated sludge. Further, it was observed that the development of the hydrolytic enzyme system in Bacillus amyloliquefaciens and P. saccharophila is strongly suppressed under anoxic and anaerobic conditions. However, the effect of anaerobic and aerobic incubation on hydrolytic enzyme activity in activated sludge was found to be small. Starch hydrolysis kinetic data from batch experiments with activated sludge followed substrate saturation kinetics that were linear with biomass concentration. Finally, the similar hydrolytic enzyme activities observed under anaerobic and aerobic phases of a sequencing batch reactor are explained by considering the aspects of enzyme location and enzyme system development under aerobic and anaerobic phases. It is proposed that the floc bound enzymes are recycled in a single sludge system so that an equilibrium exists between enzyme loss and synthesis at steady state.

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Rajagopal, Rajinikanth, and Fabrice Béline. "Anaerobic hydrolysis and acidification of organic substrates: Determination of anaerobic hydrolytic potential." Bioresource Technology 102, no. 10 (May 2011): 5653–58. http://dx.doi.org/10.1016/j.biortech.2011.02.068.

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Bochmann, G., T. Herfellner, F. Susanto, F. Kreuter, and G. Pesta. "Application of enzymes in anaerobic digestion." Water Science and Technology 56, no. 10 (November 1, 2007): 29–35. http://dx.doi.org/10.2166/wst.2007.727.

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Owing to the very low economic value of brewer's spent grains, its utilisation for biogas production is very promising. The hydrolysis of ligno-cellulose is the rate limiting step in anaerobic digestion. Enzymatic pre-treatment promotes the hydrolysis of ligno-cellulose, breaking it down to lower molecular weight substances which are ready to be utilised by the bacteria. A cheap raw multi-enzyme produced by a solid state fermentation (SSF) process is a good substitute for expensive conventional enzyme. The SSF enzyme application to spent grain has been investigated by carrying out enzymatic solubility tests, hydrolytic experiments and two-step anaerobic fermentation of spent grain. Gas chromatograph analysis was conducted to quantify fatty acids concentrations, while CH4, CO2, O2, H2 and H2S were measured to determine biogas quality by means of a gas analyser. DS, oDS, pH were also measured to analyse the anaerobic digestion. The result shows that enzyme application promotes the hydrolysis of ligno-cellulose, indicated by higher enzymatic solubility and fatty acid concentration in a hydrolytic bioreactor. Moreover, biogas production is also increased. The quality of the gases produced is also enhanced. Since the anaerobic digestion can be operated in a stable performance, it can also be concluded that SSF enzyme is compatible with anaerobic digestion.

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Lü, F., P. J. He, L. P. Hao, and L. M. Shao. "Impact of recycled effluent on the hydrolysis during anaerobic digestion of vegetable and flower waste." Water Science and Technology 58, no. 8 (October 1, 2008): 1637–43. http://dx.doi.org/10.2166/wst.2008.511.

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Two trials were established to investigate the effect of recycled effluent on hydrolysis during anaerobic co-digestion of vegetable and flower waste. Trial I evaluated the effect by regulating the flow rate of recycled effluent, while Trial II regulated the ratio of hydrolytic effluent to methanogenic effluent, which were recycled to hydrolysis reactor. Results showed that the recirculation of methanogenic effluent could enhance the buffer capability and operation stability of hydrolysis reactor. Higher recycled flow rate was favourable for microbial anabolism and further promoted hydrolysis. After 9 days of hydrolysis, the cumulative SCOD in the hydrolytic effluent reached 334, 407, 413, 581 mg/g at recycled flow rates of 0.1, 0.5, 1.0, 2.0 m3/(m3·d), respectively. It was feasible to recycling a mixture of hydrolytic and methanogenic effluent to the hydrolysis reactor. This research showed that partially introducing hydrolytic effluent into the recycled liquid could enhance hydrolysis, while excessive recirculation of hydrolytic effluent will inhibit the hydrolysis. The flow ratio 1:3 of hydrolytic to methanogenic effluent was found to provide the highest hydrolysis efficiency and degradation rate of lignocelluloses-type biomass, among four ratios of 0:1, 1:3, 1:1 and 3:1. Under this regime, after 9 days of hydrolysis, the cumulative TOC and TN in the hydrolytic effluent reached 162 mg/g and 15 mg/g, the removal efficiency of TS, VS, C and cellulose in the solid phase were 60.66%, 62.88%, 58.35% and 49.12%, respectively. The flow ratio affected fermentation pathways, i.e. lower ratio favoured propionic acid fermentation and the generation of lactic acid while higher ratio promoted butyric acid fermentation.

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Ferreiro, N., and M. Soto. "Anaerobic hydrolysis of primary sludge: influence of sludge concentration and temperature." Water Science and Technology 47, no. 12 (June 1, 2003): 239–46. http://dx.doi.org/10.2166/wst.2003.0652.

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Anaerobic hydrolysis of primary sludge from urban wastewater treatment was first studied as part of anaerobic sludge stabilisation and later as a process for readily biodegradable matter (volatile fatty acids) production in order to improve biological nutrient removal. Furthermore, hydrolysis was found to be the rate limiting step in both single- or two-step anaerobic treatment of domestic wastewater. However, the influence on the process of several factors such as sludge concentration and temperature is still barely understood, as are kinetic aspects. The aim of this work was to study the influence of sludge concentration and temperature on the hydrolytic and acidogenic conversion of primary sludge and to determine the hydrolysis kinetic coefficients at different temperatures. Specific VFA production varied from 0.17 to 0.34 gVFACOD/gVSS of raw primary sludge, depending mainly on the assay sludge concentration and, to a lesser extent, on the process temperature. The first-order hydrolysis constants were 0.038, 0.095 and 0.169 d−1 for 10, 20 and 35°C, respectively.

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Selling, Robert, Torbjörn Håkansson, and Lovisa Björnsson. "Two-stage anaerobic digestion enables heavy metal removal." Water Science and Technology 57, no. 4 (March 1, 2008): 553–58. http://dx.doi.org/10.2166/wst.2008.054.

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To fully exploit the environmental benefits of the biogas process, the digestate should be recycled as biofertiliser to agriculture. This practice can however be jeopardized by the presence of unwanted compounds such as heavy metals in the digestate. By using two-stage digestion, where the first stage includes hydrolysis/acidification and liquefaction of the substrate, heavy metals can be transferred to the leachate. From the leachate, metals can then be removed by adsorption. In this study, up to 70% of the Ni, 40% of the Zn and 25% of the Cd present in maize was removed when the leachate from hydrolysis was circulated over a macroporous polyacrylamide column for 6 days. For Cu and Pb, the mobilization in the hydrolytic stage was lower which resulted in a low removal. A more efficient two-stage process with improved substrate hydrolysis would give lower pH and/or longer periods with low pH in the hydrolytic stage. This is likely to increase metal mobilisation, and would open up for an excellent opportunity of heavy metal removal.

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9

Menzel, Theresa, Peter Neubauer, and Stefan Junne. "Role of Microbial Hydrolysis in Anaerobic Digestion." Energies 13, no. 21 (October 23, 2020): 5555. http://dx.doi.org/10.3390/en13215555.

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There is a growing need of substrate flexibility for biobased production of energy and value-added products that allows the application of variable biodegradable residues within a circular economy. It can be used to balance fluctuating energy provision of other renewable sources. Hydrolysis presents one of the biggest limitations during anaerobic digestion. Methods to improve it will result in broader process applicability and improved integration into regional material cycles. Recently, one focus of anaerobic digestion research has been directed to systems with a separate hydrolysis–acidogenesis stage as it might be promised to improve process performance. Conditions can be adjusted to each class of microorganisms individually without harming methanogenic microorganisms. Extensive research of separate biomass pretreatment via biological, chemical, physical or mixed methods has been conducted. Nevertheless, several methods lack economic efficiency, have a high environmental impact or focus on specific substrates. Pretreatment via a separate hydrolysis stage as cell-driven biotransformation in a suspension might be an alternative that enables high yields, flexible feeding and production, and a better process control. In this review, we summarize existing technologies for microbial hydrolytic biotransformation in a separate reactor stage and the impacts of substrate, operational parameters, combined methods and process design as well as remaining challenges.

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Higuchi, Y., A. Ohashi, H. Imachi, and H. Harada. "Hydrolytic activity of alpha-amylase in anaerobic digested sludge." Water Science and Technology 52, no. 1-2 (July 1, 2005): 259–66. http://dx.doi.org/10.2166/wst.2005.0526.

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Hydrolysis is usually considered to be a rate-limiting step in anaerobic digestion. For improving anaerobic solid waste treatments, it is essential to elucidate the mechanism of hydrolysis. In this study, alpha-amylase, one of the hydrolytic enzymes, was investigated for the elucidation of more precise mechanism of hydrolysis. Alpha-amylase activity of solid starch-degrading bacteria (SDB) was estimated through batch experiments with several different substrates and with distinction between cell-bound and cell-free alpha-amylase. Monitoring of newly isolated strains of SDB was done by fluorescence in situ hybridization. Results indicated that cell-bound alpha-amylase is chiefly responsible for the hydrolysis in the digested sludge, providing very useful information that the contact between microbial cells and solids is significantly important. The activity of alpha-amylase of the digested sludge remained quite low when not required, but increased as they recognized appropriate substrates. Several-fold higher activity was obtained for starch or maltose as compared to glucose only.

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11

Phothilangka, P., M. A. Schoen, M. Huber, P. Luchetta, T. Winkler, and B. Wett. "Prediction of thermal hydrolysis pretreatment on anaerobic digestion of waste activated sludge." Water Science and Technology 58, no. 7 (October 1, 2008): 1467–73. http://dx.doi.org/10.2166/wst.2008.726.

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Thermal hydrolysis is known for an efficient sludge disintegration capability to enhance biogas potential—but to which extent? Obviously, residual VSS concentration in digested sludge gives not sufficient information to predict additional biogas potential. In this paper, different types of waste activated sludge (WAS) were pre-hydrolysed by a full-scale Thermo-Pressure-Hydrolysis Process (Thermo-Druck-Hydrolyse, TDH) and break-down mechanisms on specific organic compounds were investigated. The IWA Anaerobic Digestion Model No.1 (ADM1) has been used for a systematic analysis of monitoring data gained from experimental work. The TDH process combined with anaerobic digestion can be well described by a modified ADM1 model that includes an XP-fraction (inactivated aerobic biomass and their decay products). More rapid and more complete degradation of TDH-treated sludge is represented by calibrated disintegration rate and disintegration factors, while biokinetic parameters of acetogenesis and methanogenesis show no sensitivity. TDH process impacts mainly biomass and decay products while inerts Xi already contained in the raw wastewater are hardly converted. Final concentration of soluble inerts in digestion effluent has been increased from 2% to 9% of influent COD due to thermal hydrolysis. An increase in biogas generation (ca. +80%) and in ammonia release (ca. +75%) can be explained by complete degradation of cell mass.

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Jensen, T. R., T. Lastra Milone, G. Petersen, and H. R. Andersen. "Accelerated anaerobic hydrolysis rates under a combination of intermittent aeration and anaerobic conditions." Water Science and Technology 75, no. 8 (February 10, 2017): 1944–51. http://dx.doi.org/10.2166/wst.2017.085.

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Anaerobic hydrolysis in activated return sludge was investigated in laboratory scale experiments to find if intermittent aeration would accelerate anaerobic hydrolysis rates compared to anaerobic hydrolysis rates under strict anaerobic conditions. The intermittent reactors were set up in a 240 h experiment with intermittent aeration (3 h:3 h) in a period of 24 h followed by a subsequent anaerobic period of 24 h in a cycle of 48 h which was repeated five times during the experiment. The anaerobic reactors were kept under strict anaerobic conditions in the same period (240 h). Two methods for calculating hydrolysis rates based on soluble chemical oxygen demand were compared. Two-way analysis of variance with the Bonferroni post-test was performed in order to register any significant difference between reactors with intermittent aeration and strictly anaerobic conditions respectively. The experiment demonstrated a statistically significant difference in favor of the reactors with intermittent aeration showing a tendency towards accelerated anaerobic hydrolysis rates due to application of intermittent aeration. The conclusion of the work is thus that intermittent aeration applied in the activated return sludge process can improve the treatment capacity further in full scale applications.

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Johansson, Per, Hans Carlsson, and Karin Jönsson. "Modelling of the anaerobic reactor in a biological phosphate removal process." Water Science and Technology 34, no. 1-2 (July 1, 1996): 49–55. http://dx.doi.org/10.2166/wst.1996.0355.

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A kinetic model called SIPHOR has been developed for the biological phosphate removal process. The model is based on IAWQ Activated Sludge Model No. 1, and is divided into three sub-models, one anaerobic, one anoxic and one aerobic model. This paper describes the anaerobic model and results from a calibration and verification of the model on batch experiments performed with sludges from a full-scale plant in Helsingborg and a pilot-scale plant in Malmö. Both plants were run as UCT-processes. Anaerobic batch simulations have been used to identify the following constants, P-release rate (kp), fermentation rate (kferm), anaerobic hydrolysis rate (khx), P-release/VFA-storage (fpp) and the half-saturation coefficients, Kva and Kpop. The stoichiometric constant fpp has been found to be directly related to influent waste water. If acetate is added as carbon source, fpp has a value of 0.43, for primary hydrolysed waste water the value is 0.35 and for normal primary waste water, 0.30 in Helsingborg and 0.35 in Malmö. The rate of anaerobic hydrolysis has been found to be near zero in the anaerobic reactor.

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Kadam, Rahul, Kamonwan Khanthong, Heewon Jang, Jonghwa Lee, and Jungyu Park. "Occurrence, Fate, and Implications of Heavy Metals during Anaerobic Digestion: A Review." Energies 15, no. 22 (November 17, 2022): 8618. http://dx.doi.org/10.3390/en15228618.

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Over the years, anaerobic digestion (AD) has evolved as a competent technology to retrieve energy potential from various organic substrates, including wastewater. However, the energy metabolisms of anaerobic microorganisms, biochemical reactions, and biogas production are affected by various parameters, including heavy metals. It is important to understand the interaction of heavy metals with anaerobes and their potential influence on the process to enhance energy potential. This review methodically outlines the occurrence and role of heavy metals in the AD process. Additionally, the repercussions of the most common heavy metals (i.e., Cu, Zn, Cd, Fe, and Ni) on each stage of AD (i.e., hydrolysis, acidogenesis, and methanogenesis) have been discussed. We found that traces of heavy metals can endorse anaerobic digestion, but inhibition increases with increasing concentration. Methanogenic archaea are more susceptible to heavy metal inhibition than hydrolytic and acidogenic archaea. An improved understanding and relevant intuition will help to promote biogas production along with heavy metal management.

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Sanders, W. T. M., M. Geerink, G. Zeeman, and G. Lettinga. "Anaerobic hydrolysis kinetics of particulate substrates." Water Science and Technology 41, no. 3 (February 1, 2000): 17–24. http://dx.doi.org/10.2166/wst.2000.0051.

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A mathematical description of the surface related hydrolysis kinetics for spherical particles in a batch digestion is presented as well as a verification of this model with particulate starch as a substrate. Three substrates containing starch with different particle size distributions (PSD) were used. Two were obtained from fresh potatoes by wet sieving and for the third substrate a commercially available starch was used. The substrates were batch digested at 30°C with granular sludge as inoculum and the hydrolysis efficiency was measured and fitted with the model. The results revealed that the hydrolysis rates for the three substrates were equal, viz. 0.4±0.1 g starch/m2/hour. Moreover, for the commercial starch not only the hydrolysis efficiency but also the changes within the PSD of the starch was determined several times with the use of light microscopy and image analysis. The obtained experimental PSD showed good similarity with the theoretical PSD from model calculations. This shows that thesurface of the particulate substrate is the key factor for the hydrolysis process.

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Ravi, Bhargavi, Valentine Nkongndem Nkemka, Xiying Hao, Jay Yanke, Tim A. McAllister, Hung Lee, Chitraichamy Veluchamy, and Brandon H. Gilroyed. "Effect of Bioaugmentation with Anaerobic Fungi Isolated from Ruminants on the Hydrolysis of Corn Silage and Phragmites australis." Applied Sciences 11, no. 19 (September 30, 2021): 9123. http://dx.doi.org/10.3390/app11199123.

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Anaerobic fungi produce extracellular hydrolytic enzymes that facilitate degradation of cellulose and hemicellulose in ruminants. The purpose of this work was to study the impact of three different anaerobic fungal species (Anaeromyces mucronatus YE505, Neocallimastix frontalis 27, and Piromyces rhizinflatus YM600) on hydrolysis of two different lignocellulosic substrates, corn (Zea mays L.) silage and reed (Phragmites australis (Cav.) Trin. ex Steud.). Biomass from each plant species was incubated anaerobically for 11 days either in the presence of live fungal inoculum or with heat-inactivated (control) inoculum. Headspace gas composition, dry matter loss, soluble chemical oxygen demand, concentration of volatile fatty acids, and chemical composition were measured before and after hydrolysis. While some microbial activity was observed, inoculation with anaerobic fungi did not result in any significant difference in the degradation of either type of plant biomass tested, likely due to low fungal activity or survival under the experimental conditions tested. While the premise of utilizing the unique biological activities of anaerobic fungi for biotechnology applications remains promising, further research on optimizing culturing and process conditions is necessary.

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Tsubota, Jun, Toshiaki Tsubone, and Hiroshi Tsuno. "Novel Anaerobic Digestion System Using Hyper-Thermal Anaerobic Hydrolysis Bacteria." Journal of the Japan Society of Waste Management Experts 18, no. 2 (2007): 145–51. http://dx.doi.org/10.3985/jswme.18.145.

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Jain, Sanjay, Anil K. Lala, Suresh K. Bhatia, and Arvind P. Kudchadker. "Modelling of hydrolysis controlled anaerobic digestion." Journal of Chemical Technology & Biotechnology 53, no. 4 (April 24, 2007): 337–44. http://dx.doi.org/10.1002/jctb.280530404.

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Li, Guang, He Ren, Jing Li, Xiang Kui Han, and Lian Peng Wang. "Sewage Sludge Thermal Hydrolysis Process." Advanced Materials Research 827 (October 2013): 368–73. http://dx.doi.org/10.4028/www.scientific.net/amr.827.368.

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In 110~190°C for 15~75min excess sludge thermal hydrolysis test, investigated the dissolution rate of the volatile suspended solids, Sludge SCOD, TCOD concentration change in composition of organic acids in the supernatant, and analysis the improvement of the anaerobic digestion performance. The results show that, with the increase of thermal hydrolysis temperature and extension of time, sludge supernatant on SCOD, VFA rising. At 190 °C, 75min conditions, SCOD, VFA reached the maximum 6674mg / L2630mg/ L; Sludge organic solids dissolved and the release of COD, etc. mainly in the first 45 min to complete, little change after 45min. When thermal hydrolysis temperature between 90~170°C, anaerobic digestion performance increase with temperature rise, When the temperature is higher than 170 °C, the sludge anaerobic digestion performance begins to decline.

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Rodríguez-Pimentel, Reyna I., Suyen Rodríguez-Pérez, Oscar Monroy-Hermosillo, and Florina Ramírez-Vives. "Effect of organic loading rate on the performance of two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW)." Water Science and Technology 72, no. 3 (May 12, 2015): 384–90. http://dx.doi.org/10.2166/wst.2015.223.

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Two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was carried out: hydrolysis and acidogenesis in a continuous anaerobic hydrolytic leach bed (AHLB) reactor loaded at different rates (Bv = 3.8–7 gVSSL−1d−1) and methanogenesis of leachates, diluted with municipal wastewater in an upflow anaerobic sludge blanket (UASB) reactor at organic loading rates of 6.6–13 gCODLr−1d−1. In the AHLB reactor, 51–76% and 58–71% volatile solids and chemical oxygen demand (COD) removal efficiencies were obtained. During the hydrolysis and acidogenesis phases, the effluents were at pH 4.93, the leachate had a volatile fatty acids concentration of 35 g/L and the biogas was composed only of CO2. The average methane production in the UASB in the load of 4.4 gVS L−1 d−1 in the AHLB was 3.32 LCH4Lr−1d−1 (yCH4 = 80%), with COD removal efficiency of 95% and methane yield 279 LCH4KgVS−1OFMSW degraded.

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Feng, Lei, Yuan Gao, Wei Kou, Xianming Lang, Yiwei Liu, Rundong Li, Meiling Yu, Lijie Shao, and Xiaoming Wang. "Application of the Initial Rate Method in Anaerobic Digestion of Kitchen Waste." BioMed Research International 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/3808521.

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This article proposes a methane production approach through sequenced anaerobic digestion of kitchen waste, determines the hydrolysis constants and reaction orders at both low total solid (TS) concentrations and high TS concentrations using the initial rate method, and examines the population growth model and first-order hydrolysis model. The findings indicate that the first-order hydrolysis model better reflects the kinetic process of gas production. During the experiment, all the influential factors of anaerobic fermentation retained their optimal values. The hydrolysis constants and reaction orders at low TS concentrations are then employed to demonstrate that the first-order gas production model can describe the kinetics of the gas production process. At low TS concentrations, the hydrolysis constants and reaction orders demonstrated opposite trends, with both stabilizing after 24 days at 0.99 and 1.1252, respectively. At high TS concentrations, the hydrolysis constants and the reaction orders stabilized at 0.98 (after 18 days) and 0.3507 (after 14 days), respectively. Given sufficient reaction time, the hydrolysis involved in anaerobic fermentation of kitchen waste can be regarded as a first-order reaction in terms of reaction kinetics. This study serves as a good reference for future studies regarding the kinetics of anaerobic digestion of kitchen waste.

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Zhu, Lei, Jiahou Hao, Houwei Lai, and Guibai Li. "Effects of pH Adjustment on the Release of Carbon Source of Particulate Organic Matter (POM) in Domestic Sewage." Sustainability 14, no. 13 (June 24, 2022): 7746. http://dx.doi.org/10.3390/su14137746.

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The use of anaerobic hydrolytic fermentation to develop more available carbon sources from domestic sewage influent particulate organic matter (POM) has received increasing attention. However, the slow hydrolysis rate of POM limits the application of this technology. This study aimed to improve the carbon source release efficiency of POM by pH adjustment and to reveal the hydrolysis mechanism. Results showed that adjusting the initial pH of POM to 3, 9, and 11 enhanced carbon source release in the anaerobic hydrolysis fermentation process of POM. The pretreatment under pH value of 11 contributed to the highest yield and productivity of carbon source, reaching the soluble chemical oxygen demand (SCOD) of 2782 mg/L at the 4th day. The pH 3 pretreatment was more beneficial for phosphorus resource recovery, which contributed to the highest release concentration of PO43−-P, reaching 48.2 mg/L at the 3rd day, accounting for 90% of TP. Microbial community structure analysis indicated that pH 11 preconditioning promoted the enrichment of proteolytic bacteria (Proteocatella and Proteiniclasticum) and polysaccharide hydrolytic bacteria (Trichococcus and Acinetobacter) and inhibited the growth of acetate-consuming methanogenic archaea, which contributed to the highest carbon release of POM in domestic sewage.

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Lee, Y. H., Y. C. Chung, and J. Y. Jung. "Effects of chemical and enzymatic treatments on the hydrolysis of swine wastewater." Water Science and Technology 58, no. 7 (October 1, 2008): 1529–34. http://dx.doi.org/10.2166/wst.2008.496.

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Slow degradation of swine wastewater mainly due to the particulate and recalcitrant organic matters is a main disadvantage of anaerobic digestion leading to very long solids retention time. Therefore, to accelerate hydrolysis known as the rate-limiting step of the overall digestion process, chemical treatment processes under various acidic and alkaline conditions as well as enzymatic treatment processes using cellulase and protease enzymes were tested for the hydrolysis of the swine wastewater. The effectiveness of various treatment processes was compared mainly by means of an increment of soluble organics in the treated swine wastewater. Among various treatment processes tested in this study, cellulase enzymatic treatment resulted in the most efficient hydrolysis of the swine wastewater. For the cellulase enzymatic hydrolysis, the observed hydrolytic constant value was 0.42 d−1 and 26.6% of soluble organics in the swine wastewater increased within 12 hr. Compared to untreated swine wastewater, pre-treated swine wastewater by cellulase enzymatic process showed 10.7% higher anaerobic digestibility at the end of 20 d incubation and 29% higher initial methane production rate. These results further confirmed the transformation of particulate and recalcitrant organic compounds in the swine wastewater into soluble and relatively easily biodegradable organic products by the cellulase enzymatic hydrolysis.

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Pascale, N. C., J. J. Chastinet, D. M. Bila, G. L. Sant̀Anna, S. L. Quitério, and S. M. R. Vendramel. "Enzymatic hydrolysis of floatable fatty wastes from dairy and meat food-processing industries and further anaerobic digestion." Water Science and Technology 79, no. 5 (December 11, 2018): 985–92. http://dx.doi.org/10.2166/wst.2018.508.

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Abstract The wastewater from food-processing industries is generally heavily charged with lipids and proteins. Flotation process is commonly applied to separate the hydrophobic material phase, producing flotation froth, a waste that has high levels of fats and proteins. Enzymatic hydrolysis may be used to overcome the difficulty of fat biotransformation in a subsequent anaerobic digestion. In the present work, wastes from the flotation process of two industries (dairy and poultry slaughterhouse) were hydrolyzed with a commercial lipase and without enzyme addition (control). The effect of adjusting the pH at the beginning of the hydrolytic assays was also investigated. The long chain free fatty acids (LCFAs) released were identified and quantified and 5-d digestion assays were conducted with the hydrolyzed material. The results indicated that the hydrolysis assays conducted with initial pH adjusted to 7.0 and the utilization of a commercial enzyme promoted a higher increase in amounts of LCFAs, particularly of unsaturated acids. In most anaerobic digestion assays, the specific methane production showed a decreasing trend with the increase of unsaturated fatty acids in the medium. In general, the utilization of a commercial enzyme (lipase) in the hydrolysis process did not contribute to enhancing methane production in 5-d anaerobic digestion assays.

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Pavlostathis, S. G., and E. Giraldo-Gomez. "Kinetics of Anaerobic Treatment." Water Science and Technology 24, no. 8 (October 1, 1991): 35–59. http://dx.doi.org/10.2166/wst.1991.0217.

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A review of the kinetics of anaerobic treatment and the reported values of such kinetic parameters as the maximum specific substrate utilization rate (k), the half-saturation constant (Ks), the microbial growth yield (Y), and the microorganism decay rate constant (b) are presented. The available kinetic information is presented for each subprocess: (a) hydrolysis of complex, paniculate organic materials; (b) fermentation of amino acids and sugars; (c) anaerobic oxidation of long-chain fatty acids and alcohols; (d) anaerobic oxidation of intermediary products (such as short-chain fatty acids); (e) homoacetogenesis; and (f) methanogenesis. The intrinsic rates of each step as well as mass transfer limitations and their effect on the intrinsic kinetics are discussed and areas requiring further research are also identified. Substantial variation exists in the reported values of the kinetic coefficients. This variation is due in part to the variability in mode of operation, environmental and operational conditions in the various studies as well as to the lack of a widely accepted standard procedure for measuring and expressing the biokinetic coefficients. The hydrolysis step is usually assumed to follow first-order kinetics. Whenever the kinetics of the hydrolysis step were studied, they were generally found to be the limiting-step in the overall conversion of complex substrates to methane. With the exception of the hydrolysis step, all other subprocesses of anaerobic treatment have been successfully modeled by following Monod kinetics. The Contois and Chen & Hashimoto model has also been used quite extensively to account for the effect of influent substrate concentration on effluent quality. Based on a brief overview of the observed phenomena related to the kinetics of mass transfer in methanogenesis, it is concluded that with but few exceptions, the evidence for the significance of mass transfer effects in the different reactor configurations is circumstantial and, in some cases, contradictory. Our understanding of the kinetics of paniculate substrate removal in biofilms is still incomplete for engineering applications, and more research is necessary.

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Oosterhuis, Mathijs, Davy Ringoot, Alexander Hendriks, and Paul Roeleveld. "Thermal hydrolysis of waste activated sludge at Hengelo Wastewater Treatment Plant, The Netherlands." Water Science and Technology 70, no. 1 (March 20, 2014): 1–7. http://dx.doi.org/10.2166/wst.2014.107.

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The thermal hydrolysis process (THP) is a sludge treatment technique which affects anaerobic biodegradability, viscosity and dewaterability of waste activated sludge (WAS). In 2011 a THP-pilot plant was operated, connected to laboratory-scale digesters, at the water board Regge en Dinkel and in cooperation with Cambi A.S. and MWH Global. Thermal hydrolysis of WAS resulted in a 62% greater volatile solids (VS) reduction compared to non-hydrolysed sludge. Furthermore, the pilot digesters could be operated at a 2.3 times higher solids loading rate compared to conventional sludge digesters. By application of thermal sludge hydrolysis, the overall efficiency of the sludge treatment process can be improved.

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Novita, Elida, Sri Wahyuningsih, Subdatul Widad, and Hendra Andiananta Pradana. "Reduksi Bahan Organik Kulit Kopi dan Eceng Gondok Terhidrolisis Menggunakan Proses Anaerbik." Jurnal Keteknikan Pertanian 9, no. 1 (May 18, 2021): 23–30. http://dx.doi.org/10.19028/jtep.09.1.23-30.

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Coffee pulp and water hyacinth are a biomass source that can be used to feeding material for biogas production as energy an anaerobic digester. But coffee pulp and water hyacinth contain lignin. The Alkaline or base hydrolysis is a method of the solving chemical structure of lignin compounds using a strong acid and base. The focus of research investigated the base hydrolysis with NaOH in coffee pulp and water hyacinth an anaerobic process for organic material reduction. The research design in laboratory conduct of organic materials reduction on coffee pulp and water hyacinth used Completely Random Design (CRD). Anaerobic treatments were without hydrolysis (H1), only the coffee pulp with hydrolysis (H2), only water hyacinth with hydrolysis (H3) and all with hydrolysis (H4). The highest NaOH concentration for lignin reduction on the base hydrolysis was 60 ppm. The analysis of variants with significantly (p<0.05) showed all treated differently. Anerobic treatment of the coffee pulp and water hyacinth (H4) had the highest value organic material reduction. The efficiency of organic material reduction i.e. C/N, BOD and COD was in sequence namely 64.22 ± 0.02; 75.23 ± 0.02 dan 52.55 ± 0.04.

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Petri, Jessica, Yoshio Nakatani, Martin G. Montgomery, Scott A. Ferguson, David Aragão, Andrew G. W. Leslie, Adam Heikal, John E. Walker, and Gregory M. Cook. "Structure of F1-ATPase from the obligate anaerobeFusobacterium nucleatum." Open Biology 9, no. 6 (June 2019): 190066. http://dx.doi.org/10.1098/rsob.190066.

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The crystal structure of the F1-catalytic domain of the adenosine triphosphate (ATP) synthase has been determined from the pathogenic anaerobic bacteriumFusobacterium nucleatum. The enzyme can hydrolyse ATP but is partially inhibited. The structure is similar to those of the F1-ATPases fromCaldalkalibacillus thermarum, which is more strongly inhibited in ATP hydrolysis, and inMycobacterium smegmatis, which has a very low ATP hydrolytic activity. The βE-subunits in all three enzymes are in the conventional ‘open’ state, and in the case ofC. thermarumandM. smegmatis, they are occupied by an ADP and phosphate (or sulfate), but inF. nucleatum, the occupancy by ADP appears to be partial. It is likely that the hydrolytic activity of theF. nucleatumenzyme is regulated by the concentration of ADP, as in mitochondria.

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Ahn, Y. H., J. Y. Bae, S. M. Park, and K. S. Min. "Anaerobic digestion elutriated phased treatment of piggery waste." Water Science and Technology 49, no. 5-6 (March 1, 2004): 181–89. http://dx.doi.org/10.2166/wst.2004.0752.

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The performance of a novel high-rate anaerobic process, the anaerobic digestion elutriated phased treatment (ADEPT) process, for treating a slurry-type piggery waste (55 g COD/L and 37 g TS/L) was investigated. The ADEPT process consists of an acid elutriation slurry reactor for hydrolysis and acidification, followed by an upflow anaerobic sludge bed reactor for methanification. This process provides stable and high system performance with short HRT (7.4 d) and better effluent quality (2 g SCOD/L and 0.68 g VSS/L) due to the alkaline pH condition for hydrolysis/acidification phase, high refractory solids removal and ammonia toxicity reduction. The optimum pH and HRT for hydrolysis/acidogenesis of the piggery waste were 9 and 5 days at both 35°C and 55°C conditions. The hydrolysis and acidification rate in the mesophilic reactor were 0.05 d-1 and 0.11 d-1 , meaning that hydrolysis was a limiting step. SCOD production by the hydrolysis was about 0.26 g SCOD/g VSfed (3.6 g SCOD/g VS reduction). Methane production and content in the system were 0.3 L CH4/g VSfed (0.67 L CH4/g VS destroyed) and 80%, respectively, corresponding to 0.23 L CH4/g COD removal (@STP).

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Kim, H. W., S. K. Han, and H. S. Shin. "Anaerobic co-digestion of sewage sludge and food waste using temperature-phased anaerobic digestion process." Water Science and Technology 50, no. 9 (November 1, 2004): 107–14. http://dx.doi.org/10.2166/wst.2004.0547.

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This study was performed to overcome the low efficiency of anaerobic digestion of sewage sludge and food waste by combining temperature-phased digestion, sequencing batch operation, and co-digestion technology. It was demonstrated that the temperature-phased anaerobic sequencing batch reactor (TPASBR) system for the co-digestion of sewage sludge and food waste resulted in enhanced volatile solids (VS) reduction and methane production rate. At the organic loading rate (OLR) of 2.7 g VS/l/d, the TPASBR system showed the higher VS reduction (61.3%), CH4 yield (0.28 l/g VSadded) and CH4 production rate (0.41 l CH4/l/d) than those (0.29 l CH4/l/d) of the mesophilic two-stage ASBR (MTSASBR). In the specific methanogenic activity (SMA) tests on thermophilic biomass of the TPASBR system, the average SMA of acetate (93 ml CH4/gVSS/d) was much higher than those of propionate (46 ml CH4/g VSS/d) and butyrate (76 ml CH4/g VSS/d). Also, higher specific hydrolytic activity (SHA, 217 mg COD/g VSS/d) of the biomass supported fast hydrolysis under thermophilic conditions. The track study revealed that the most active period of the 24 h cycle was between 6 and 12 h. The enhanced performance of the TPASBR system could be attributed to longer solids retention time, fast hydrolysis, higher CH4 conversion rate, and balanced nutrient condition of co-substrate. It was verified that this combination could be a promising and practical alternative for the simultaneous recycling of two types of organic fraction of municipal solid waste (OFMSW) with high stability.

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Toja Ortega, Sara, Mario Pronk, and Merle K. de Kreuk. "Anaerobic hydrolysis of complex substrates in full-scale aerobic granular sludge: enzymatic activity determined in different sludge fractions." Applied Microbiology and Biotechnology 105, no. 14-15 (July 24, 2021): 6073–86. http://dx.doi.org/10.1007/s00253-021-11443-3.

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Abstract Complex substrates, like proteins, carbohydrates, and lipids, are major components of domestic wastewater, and yet their degradation in biofilm-based wastewater treatment technologies, such as aerobic granular sludge (AGS), is not well understood. Hydrolysis is considered the rate-limiting step in the bioconversion of complex substrates, and as such, it will impact the utilization of a large wastewater COD (chemical oxygen demand) fraction by the biofilms or granules. To study the hydrolysis of complex substrates within these types of biomass, this paper investigates the anaerobic activity of major hydrolytic enzymes in the different sludge fractions of a full-scale AGS reactor. Chromogenic substrates were used under fully mixed anaerobic conditions to determine lipase, protease, α-glucosidase, and β-glucosidase activities in large granules (>1 mm in diameter), small granules (0.2–1 mm), flocculent sludge (0.045–0.2 mm), and bulk liquid. Furthermore, composition and hydrolytic activity of influent wastewater samples were determined. Our results showed an overcapacity of the sludge to hydrolyze wastewater soluble and colloidal polymeric substrates. The highest specific hydrolytic activity was associated with the flocculent sludge fraction (1.5–7.5 times that of large and smaller granules), in agreement with its large available surface area. However, the biomass in the full-scale reactor consisted of 84% large granules, making the large granules account for 55–68% of the total hydrolytic activity potential in the reactor. These observations shine a new light on the contribution of large granules to the conversion of polymeric COD and suggest that large granules can hydrolyze a significant amount of this influent fraction. The anaerobic removal of polymeric soluble and colloidal substrates could clarify the stable granule formation that is observed in full-scale installations, even when those are fed with complex wastewaters. Key points • Large and small granules contain >70% of the hydrolysis potential in an AGS reactor. • Flocculent sludge has high hydrolytic activity but constitutes <10% VS in AGS. • AGS has an overcapacity to hydrolyze complex substrates in domestic wastewater. Graphical abstract

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Cysneiros, D., C. J. Banks, and S. Heaven. "Anaerobic digestion of maize in coupled leach-bed and anaerobic filter reactors." Water Science and Technology 58, no. 7 (October 1, 2008): 1505–11. http://dx.doi.org/10.2166/wst.2008.518.

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The methane potential of a leach bed reactor (LBR) coupled to an anaerobic filter (AF) was assessed using energy maize (Zea mays) as substrate. Four LBRs were used operated as pairs, with and without leachate recirculation, over two feed cycles with retention times of 14 and 28 days. Performance was estimated from the total solids destruction in the LBR, and the volatile fatty acid (VFA) and soluble chemical oxygen demand (SCOD) in the leachate. Overall conversion of fresh substrate added to the combined system was good although the organic loading rate (OLR) was limited. The coupled LBR demonstrated improved hydrolysis performance promoted by good buffering, and the AF showed rapid conversion of leachate SCOD into methane with possible further hydrolysis and acidification. Theoretical estimation of the methane potential showed that between 20–40% of the methane was formed in the LBR and was not captured in this trial.

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Arntz, H. J., E. Stoppok, and K. Buchholz. "Anaerobic hydrolysis of beet pulp ? Discontinuous experiments." Biotechnology Letters 7, no. 2 (February 1985): 113–18. http://dx.doi.org/10.1007/bf01026681.

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Coombs, J. "Anaerobic digestion and carbohydrate hydrolysis of waste." Biomass 9, no. 3 (January 1986): 236. http://dx.doi.org/10.1016/0144-4565(86)90093-4.

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35

Li, Guang, Xiao Xia Jiao, Jing Li, Xiang Kui Han, and Lian Peng Wang. "Combination of High Pressure and Thermal Hydrolysis Pretreatment Effect on Sludge." Advanced Materials Research 838-841 (November 2013): 18–22. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.18.

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In 110-190°C for 15-75 min of excess sludge thermal hydrolysis experiment, inspected the volatile suspended solid dissolution rate, the concentration of sludge SCOD, TCOD, components of organic acids in the supernatant fluid changes,such as sewage thermal hydrolysis characteristics, analysis the effect to improve the performance of sludge anaerobic digestion. The results show that with the increase of thermal hydrolysis temperature and time, SCOD and VFA in the sludge supernatant on rising. Under the condition of 190°C,75min, SCOD and VFA reached a maximum of 6674 mg/L,2630 mg/L; Release of sludge organic dissolved solids,COD and other major completed in the first 45 min,after 45 min changed little; Thermal hydrolysis temperature was between 90~170°C,sludge anaerobic digestion performance increases with temperature,when the temperature was higher than 170°C,sludge anaerobic digestion performance began to decline.

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36

Christ, O., P. A. Wilderer, R. Angerhöfer, and M. Faulstich. "Mathematical modeling of the hydrolysis of anaerobic processes." Water Science and Technology 41, no. 3 (February 1, 2000): 61–65. http://dx.doi.org/10.2166/wst.2000.0056.

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In the recently published dynamic simulation model for mesophilic digestion of sewage sludge the hydrolysis constant refers to the total dry solid content without regarding their composition. To apply these models to the digestion of municipal solid waste, the hydrolysis constants of the various fractions must be considered. The major constituents of organic waste were identified as carbohydrates, proteins and lipids. For these three constituents the hydrolysis constants for thermophilic digestion were determined. The implementation of these constants into the existing dynamic models allowed a reasonable characterization of the digestion of municipal organic waste.

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Divya, D., L. R. Gopinath, S. Sreeremya, and S. Indran. "Enhancement of Substrate Decomposition through Potential Hydrolytic Bacteria for Cumulative Biogas Production." International Journal of Applied Sciences and Biotechnology 6, no. 4 (December 28, 2018): 386–96. http://dx.doi.org/10.3126/ijasbt.v6i4.22131.

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Scenarios focus on the practical behavior of anaerobic decomposition systems to enhance biogas production, in addition to assure economic progression and ecological sustainability. The present study has framed to identify the potential hydrolytic bacteria from five different sources since principally the efficacy of hydrolytic bacteria determines the rate of hydrolysis of anaerobic decomposition and thereby biogas production. Among the 40 dominant bacteria isolated from diverse bases, 10 isolates were selected as efficient through preliminary screening. Consequently, the premier enzyme activity obtained from the isolate G5 obtained from goat rumen fluid for cellulase (44.16±1.00 U/ml), protease (260.63±1.35 U/ml) and lipase (33.20 ± 0.81 U/ml). Morphological, biochemical and molecular characterization revealed that G5 is Bacillus sp. DDG5 (KM093856.1). A range of pH (7.0-7.5) and temperature (40oC) was sufficient for the highest activity of hydrolytic enzymes experienced. Biogas production using cow dung showed an improved efficiency of 9.54 % in Bacillus sp. DDG5 treated tank (70.16 ± 1.54 %) in contrast to control (58.13 ± 1.02%) at 30th day. However, this study established that Bacillus sp. DDG5 obtained from goat rumen fluid is the promising hydrolytic bacteria, since it can be applied for proficient hydrolysis of various organic materials to enhance methane production in outlook. Int. J. Appl. Sci. Biotechnol. Vol 6(4): 386-396

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Zeeman, G., and W. Sanders. "Potential of anaerobic digestion of complex waste(water)." Water Science and Technology 44, no. 8 (October 1, 2001): 115–22. http://dx.doi.org/10.2166/wst.2001.0479.

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Although they differ greatly in origin complex waste(water)s mainly consist of proteins, lipids, carbohydrates and sometimes lignin in addition. Hydrolysis is the first and generally rate-limiting step in the process of anaerobic digestion of particulate organic substrates. Hydrolysis of particulate polymers can be described by Surface Based Kinetics, but for use in practice the empirical first order relation is advised. Unlike the hydrolysis of protein and carbohydrate, lipid hydrolysis is hardly occurring in the absence of methanogenesis. The latter is probably a physical rather than a biological process and affects the choice for either a one- or a two-step (phase) anaerobic reactor. In the chain of collection and transport, complex wastes often become complex wastewaters simply because of dilution. Dilution not only changes the reactor technology to be applied but also complicates the post-treatment and possibilities for resource recovery. Combining concentrated with diluted waste streams will almost always end up in much more complicated treatment technologies.

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Kübler, Hans, and Cosima Schertler. "Three-phase anaerobic digestion of organic wastes." Water Science and Technology 30, no. 12 (December 1, 1994): 367–74. http://dx.doi.org/10.2166/wst.1994.0636.

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A new process has been developed for efficient anaerobic digestion of the organic fraction of municipal solid waste. The BTA-process comprises pretreatment of incoming waste followed by a three-phase anaerobic biology consisting of acidification, solids hydrolysis and methanization. One main fraction of organic wastes is cellulose causing a diauxie effect during anaerobic digestion. Acidification of the pretreated waste occurs spontaneously, and is not limited by the level of anaerobic microorganisms in the waste. Solid retention time and pH in the hydrolysis reactor have an important influence on volatile solids degradation. Favourable conditions are pH 6.7 and solid retention times of 50 to 60 hours. Cellulose to lignin ratios in the products indicate an extensive degradation of cellulose.

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Váchalová, Radka, Ladislav Kolář, Jan Frelich, Jan Váchal, Kateřina Volfová, Milan Kobes, Václav Kudrna, Petr Homolka, Petr Marada, and Miroslav Dumbrovský. "Anaerobic degradability and acid hydrolysis of organic manure as an illustration of dietary organic matter utilization in cows in relation to lactation period." Acta Veterinaria Brno 83, no. 4 (2014): 363–69. http://dx.doi.org/10.2754/avb201483040363.

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The objective of the present paper was to verify whether the method of studying the anaerobic degradability of organic matter of excrements could reveal the utilization of dietary organic matter in the digestive tract of ruminants in relation to the lactation period, and whether it could be replaced by a cheaper and easier method of acid hydrolysis of excrements. Changes in anaerobic degradability and hydrolysis yields of excrements were investigated in an experimental herd of 30 cows divided into two groups differing in their lactation period by 30 days. The results document that anaerobic degradability is a suitable indicator of anaerobic digestion conditions in the digestive tract of animals and of the fitness of their organism. However, the results of excrement hydrolysis according to the Rovira and Vallejo (2002) method were hardly reproducible and so they could not be used, when only the very labile organic fraction is evaluated. The evaluation of the sum of very labile fractions and semi-labile fraction provides easily available values, but these are only orientative values that cannot replace the costly and labour-consuming determination of anaerobic degradability of excrements.

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Chauzy, J., S. Graja, F. Gerardin, D. Crétenot, L. Patria, and P. Fernandes. "Minimisation of excess sludge production in a WWTP by coupling thermal hydrolysis and rapid anaerobic digestion." Water Science and Technology 52, no. 10-11 (November 1, 2005): 255–63. http://dx.doi.org/10.2166/wst.2005.0701.

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In many cases, reducing sludge production could be the solution for wastewater treatment plants (WWTP) that here difficulty evacuating the residuals of wastewater treatment. The aim of this study was to test the possibility of minimising the excess sludge production by coupling a thermal hydrolysis stage and an anaerobic digestion with a very short HRT. The tests were carried out on a 2,500 p.e. pilot plant installed on a recycling loop between the clarifier and the actived sludge basin. The line equipped with the full scale pilot plant produced 38% TSS less than the control line during a 10 week period. Moreover, the rapid anaerobic digestion removed, on average, more than 50% of the total COD load with a hydraulic retention time (HRT) of 3 days. Lastly, the dryness of the remaining excess sludge, sanitised by the thermal hydrolysis, was more than 35% with an industrial centrifuge. This combination of thermal hydrolysis and rapid anaerobic digestion equally permits a significant gain of compactness compared to traditional anaerobic digesters.

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42

Hirmiz, Yousif, Youngseck Hong, and Younggy Kim. "A new model with serial hydrolysis reactions for the anaerobic digestion of waste activated sludge under thermophilic conditions." Environmental Science: Water Research & Technology 5, no. 12 (2019): 2182–92. http://dx.doi.org/10.1039/c9ew00619b.

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Hydrolysis is one of the rate-limiting reactions in the anaerobic digestion (AD) of wastewater sludge; thus, reliable kinetic models for hydrolysis reactions are essential in numerical simulations of AD.

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43

Hassan, Siti Roshayu, Yung-Tse Hung, Irvan Dahlan, and Hamidi Abdul Aziz. "Kinetic Study of the Anaerobic Digestion of Recycled Paper Mill Effluent (RPME) by Using a Novel Modified Anaerobic Hybrid Baffled (MAHB) Reactor." Water 14, no. 3 (January 27, 2022): 390. http://dx.doi.org/10.3390/w14030390.

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The process kinetics of an anaerobic digestion process for treating recycled paper mill effluent (RPME) was investigated. A laboratory-scale modified anaerobic hybrid baffled reactor (MAHB) was operated at hydraulic retention times of 1, 3, 5, and 7 days, and the results were analyzed for the kinetic models. A kinetic study was conducted by examining the phase kinetics of the anaerobic digestion process, which were divided into three main stages: hydrolysis kinetics, acetogenesis kinetics, and methane production kinetics. The study demonstrated that hydrolysis was the rate-limiting step. The applied Monod and Contois kinetic models showed satisfactory prediction with μmax values of 1.476 and 0.6796 L day−1, respectively.

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Piao, Dong-Mei, Young-Chae Song, and Dong-Hoon Kim. "Bioelectrochemical Enhancement of Biogenic Methane Conversion of Coal." Energies 11, no. 10 (September 27, 2018): 2577. http://dx.doi.org/10.3390/en11102577.

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This study demonstrated the enhancement of biogenic coal conversion to methane in a bioelectrochemical anaerobic reactor with polarized electrodes. The electrode with 1.0 V polarization increased the methane yield of coal to 52.5 mL/g lignite, which is the highest value reported to the best of our knowledge. The electrode with 2.0 V polarization shortened the adaptation time for methane production from coal, although the methane yield was slightly less than that of the 1.0 V electrode. After the methane production from coal in the bioelectrochemical reactor, the hydrolysis product, soluble organic residue, was still above 3600 mg chemical oxygen demand (COD)/L. The hydrolysis product has a substrate inhibition effect and inhibited further conversion of coal to methane. The dilution of the hydrolysis product mitigates the substrate inhibition to methane production, and a 5.7-fold dilution inhibited the methane conversion rate by 50%. An additional methane yield of 55.3 mL/g lignite was obtained when the hydrolysis product was diluted 10-fold in the anaerobic toxicity test. The biogenic conversion of coal to methane was significantly improved by the polarization of the electrode in the bioelectrochemical anaerobic reactor, and the dilution of the hydrolysis product further improved the methane yield.

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Flotats, X., J. Palatsi, B. K. Ahring, and I. Angelidaki. "Identifiability study of the proteins degradation model, based on ADM1, using simultaneous batch experiments." Water Science and Technology 54, no. 4 (August 1, 2006): 31–39. http://dx.doi.org/10.2166/wst.2006.523.

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The objective of the present study is to analyse kinetic and stoichiometric parameter values of gelatine anaerobic degradation at thermophilic range, based on an experiment designed to elucidate if volatile fatty acids (VFA) are inhibitors of the hydrolysis process. Results showed that VFA are not inhibiting the hydrolysis process. The ADM1 model adequately expressed the consecutive steps of hydrolysis and acidogenesis, with estimated kinetic values corresponding to a fast acidogenesis and slower hydrolysis. The hydrolysis was found to be the rate limiting step of anaerobic degradation. Estimation of yield coefficients based on the relative initial slopes of VFA profiles obtained in a simple batch experiment produced satisfactory results. From the identification study, it was concluded that it is possible to determine univocally the related kinetic parameter values for protein degradation if the evolution of amino acids is measured in simultaneous batch experiments, with different initial protein and amino acids concentrations.

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Dumlu, Lütfiye, Asli Seyhan Ciggin, Stefan Ručman, and N. Altınay Perendeci. "Pretreatment, Anaerobic Codigestion, or Both? Which Is More Suitable for the Enhancement of Methane Production from Agricultural Waste?" Molecules 26, no. 14 (July 9, 2021): 4175. http://dx.doi.org/10.3390/molecules26144175.

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Pretreatment and codigestion are proven to be effective strategies for the enhancement of the anaerobic digestion of lignocellulosic residues. The purpose of this study is to evaluate the effects of pretreatment and codigestion on methane production and the hydrolysis rate in the anaerobic digestion of agricultural wastes (AWs). Thermal and different thermochemical pretreatments were applied on AWs. Sewage sludge (SS) was selected as a cosubstrate. Biochemical methane potential tests were performed by mixing SS with raw and pretreated AWs at different mixing ratios. Hydrolysis rates were estimated by the best fit obtained with the first-order kinetic model. As a result of the experimental and kinetic studies, the best strategy was determined to be thermochemical pretreatment with sodium hydroxide (NaOH). This strategy resulted in a maximum enhancement in the anaerobic digestion of AWs, a 56% increase in methane production, an 81.90% increase in the hydrolysis rate and a 79.63% decrease in the technical digestion time compared to raw AWs. On the other hand, anaerobic codigestion (AcoD) with SS was determined to be ineffective when it came to the enhancement of methane production and the hydrolysis rate. The most suitable mixing ratio was determined to be 80:20 (Aws/SS) for the AcoD of the studied AWs with SS in order to obtain the highest possible methane production without any antagonistic effect.

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Korczak, M. K., S. Koziarski, and B. Komorowska. "Anaerobic Treatment of Pulp Mill Effluents." Water Science and Technology 24, no. 7 (October 1, 1991): 203–6. http://dx.doi.org/10.2166/wst.1991.0201.

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A laboratory-scale study on the anaerobic treatment of selected pulp mill streams was carried out in a collaboration between the Research Institute for Environmental Protection and Designing Office of Water and Waste Disposal. Anaerobic treatment of effluents from acid hydrolysis of wood from sulfate cellulose production, and effluents from the sulfite cellulose fibers washing was investigated. The results indicated 80% COD removal and the average methane generation was found to be 340 Ncm3/gCOD removed in case of highly polluted (COD = 63 kgO2/m3) acid hydrolysis effluents. The waste from cellulose washing contained, beside sugars, alsorefractory compounds, such as high-molecular-mass lignin derivatives, resins and tannins. According to that, only 20-30% COD removal was obtained and the methane generation was 270-360 Ncm3/g COD removed.

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48

Amiri, Leyla, Mohammad Ali Abdoli, and Naser Mehrdadi. "Effect of Thermal Hydrolysis on Anaerobic Digester Performance." Journal of Green Engineering 4, no. 3 (2015): 235–44. http://dx.doi.org/10.13052/jge1904-4720.434.

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Donoso-Bravo, A., C. Retamal, M. Carballa, G. Ruiz-Filippi, and R. Chamy. "Influence of temperature on the hydrolysis, acidogenesis and methanogenesis in mesophilic anaerobic digestion: parameter identification and modeling application." Water Science and Technology 60, no. 1 (July 1, 2009): 9–17. http://dx.doi.org/10.2166/wst.2009.316.

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The effect of temperature on the kinetic parameters involved in the main reactions of the anaerobic digestion process was studied. Batch tests with starch, glucose and acetic acid as substrates for hydrolysis, acidogenesis and methanogenesis, respectively, were performed in a temperature range between 15 and 45°C. First order kinetics was assumed to determine the hydrolysis rate constant, while Monod and Haldane kinetics were considered for acidogenesis and methanogenesis, respectively. The results obtained showed that the anaerobic process is strongly influenced by temperature, with acidogenesis exerting the highest effect. The Cardinal Temperature Model 1 with an inflection point (CTM1) fitted properly the experimental data in the whole temperature range, except for the maximum degradation rate of acidogenesis. A simple case-study assessing the effect of temperature on an anaerobic CSTR performance indicated that with relatively simple substrates, like starch, the limiting reaction would change depending on temperature. However, when more complex substrates are used (e.g. sewage sludge), the hydrolysis might become more quickly into the limiting step.

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Mu, De Wei, and Ning Zuo. "Characteristics of Organic Matters Translation and Removal on Sludge Reduction HA-A/A-MCO Process." Applied Mechanics and Materials 253-255 (December 2012): 888–91. http://dx.doi.org/10.4028/www.scientific.net/amm.253-255.888.

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In order to explore methods of improving phosphorous and nitrogen removal in sludge reduction technologies, an advanced process combining sludge reduction and phosphorous and nitrogen removal was developed, for short, HA-A/A-MCO Process (Hydrolysis-Acidogenosis -Anaerobic/Anoxic-Multistep Continuous Oxic tank). Under the condition of this process achieving favorable effect of phosphorous and nitrogen removal and sludge reduction, test results of the process treating campus wastewater showed that when influent COD was 316-407mg/L, effluent COD was lower than 18mg/L, and COD removal rate exceeded 96%. When return ratio of anaerobic P-release sludge entering into hydrolysis-acidification tank was about 2% of influent flow, most anaerobic P-release sludge was translated into organic matter and it mainly contained VFA(about 275mg/L), which was 4.74 times as much as that(58mg/L) in original sewage. Supernatant which was rich in VFA from hydrolysis-acidification tank entered into subsequent A2/O cells, which could provide affluent carbon source for phosphorous and nitrogen removal.

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Journal articles on the topic 'Anaerobic hydrolysis'

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