Anaerobic Digestion Of Solid Waste Research Articles

Co-digestion of solid-liquid waste from citrus agroindustrial: Effect of hydraulic retention time and organic loading rate on H2 production in a long-term continuous operation leach bed reactor

The Leach Bed Reactor (LBR) application is a promising alternative for the anaerobic digestion of solid waste and wastewater. In this study, the LBR was continuously operated for 160 days in four different phases, for co-fermentation of solid and liquid waste from the citrus agroindustry, at 37 °C, evaluating the effect of hydraulic retention time (HRT) and organic loading rate (OLR). The maximum volumetric hydrogen production (VHPR) was observed at an HRT of 12h (958.3 mLH2.L-1.d-1); however, the highest hydrogen yield (HY) was identified at an HRT of 24h (104.9 mLH2.g-1CHO). Based on the metabolic characteristics of microorganisms identified in higher relative abundance, by 16S rRNA sequencing, such as Lactobacillus, Caproicoproducens, Bifidobacterium, Olsenella, and Solobacterium, an occurrence of chain elongation pathways in the production of butyric and caproic acids was inferred, with hydrogen production resulting from the lactic acid oxidation. The maximum electricity production potential of 16.3 kWh.m-3 liquor was estimated.

Technological Prospection and Flowchart for Production of Biogas Enriched with Hydrogen: A Proposal for Renewable Energy Sources

Over time, environmental issues have taken on significant proportions worldwide, making using renewable energy sources increasingly trivial, notorious, and indispensable. Projects focused on sustainability enable the expansion and diversification of current energy matrices, such as the potential use of biogas as an alternative source. Therefore, the project aimed to develop a flowchart proposal through technological prospection, given the production of biogas enriched with hydrogen through anaerobic digestion of solid waste. Thus, a technological prospecting of patents and quantitative analysis of scientific articles was carried out to show an overview of the production of biogas associated with hydrogen from 2012 to 2022, based on the studies that analyzed the viability and efficiency of the use of hydrogen for biogas production.

Potentiality of municipal sludge for biological gas production at Soba Station South of Khartoum (Sudan)

Potentiality of municipal sludge for biological gas production at Soba Station South of Khartoum (Sudan)

Biogas from Tannery Solid Waste Anaerobic Digestion Is Driven by the Association of the Bacterial Order Bacteroidales and Archaeal Family Methanosaetaceae.

The search for renewable energies has been one of the biggest challenges of the last decades. Sludge and solid wastes of many sources have been used to produce biogas of high calorific value. Thus, this work aimed to evaluate the biogas production of solid waste originating from a tannery that uses chromium salts as a tanning agent and to characterize the physicochemical parameters and microbial composition of the biogas-producing biomass. Wastes were collected and the parameters were evaluated at the initial and final time points of the anaerobic incubation process. At the end of 150days, there was a production of 26.1mLg-1 VSS of biogas with 52% of methane. The highest amount of biomethane observed was related to the archaeal family Methanosaetaceae and bacterial order Bacteroidales. Knowledge about changes in the microbial composition can provide tools for manipulation, isolation, and inoculation of the microorganisms inside the bioreactors to maximize methane production.

Modelling hydrolysis: Simultaneous versus sequential biodegradation of the hydrolysable fractions

Hydrolysis is considered the limiting step during solid waste anaerobic digestion (including co-digestion of sludge and biosolids). Mechanisms of hydrolysis are mechanistically not well understood with detrimental impact on model predictive capability. The common approach to multiple substrates is to consider simultaneous degradation of the substrates. This may not have the capacity to separate the different kinetics. Sequential degradation of substrates is theoretically supported by microbial capacity and the composite nature of substrates (bioaccessibility concept). However, this has not been experimentally assessed. Sequential chemical fractionation has been successfully used to define inputs for an anaerobic digestion model. In this paper, sequential extractions of organic substrates were evaluated in order to compare both models. By removing each fraction (from the most accessible to the least accessible fraction) from three different substrates, anaerobic incubation tests showed that for physically structured substrates, such as activated sludge and wheat straw, sequential approach could better describe experimental results, while this was less important for homogeneous materials such as pulped fruit. Following this, anaerobic incubation tests were performed on five substrates. Cumulative methane production was modelled by the simultaneous and sequential approaches. Results showed that the sequential model could fit the experimental data for all the substrates whereas simultaneous model did not work for some substrates.

Production and characterization of β-glucosidase from Aspergillus niger fermentation: Application for organic fraction of municipal solid waste hydrolysis and methane enhancement.

The anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) is currently an attractive treatment process with energy production in the form of biogas. Hydrolysis is the rate-limiting step for the anaerobic digestion of solid wastes. Thus, in the present study fungal enzymatic pretreatment of OFMSW was applied to enhance biogas production. Two enzyme cocktails rich on β-glucosidase were produced from submerged fermentation of Aspergillus niger on basal medium using OFMSW as carbon source and urea (Urea cocktail) and Ulva rigida as nitrogen source (Ulva cocktail). Ulva cocktail displayed an important effect on OFMSW solubilization. Therefore, an increase of reducing sugar concentration about 60% was obtained which was in correlation with chemical oxygen demand (COD) increase. The performance of enzymatic pretreatment on anaerobic digestion of OFMSW was studied by conducting biochemical methane potential tests. Results showed that the enzymatic pretreatment improved methane yield of OFMSW even at high solid concentration. High methane yield about 500 ml/g total volatile solid was obtained, which corresponds up to 68% enhancement over the control.

PRODUCTION OF BIOGAS FROM SOLID ORGANIC WASTES THROUGH ANAEROBIC DIGESTION

Anaerobic digestion treatments have often been used for biological stabilization of solid wastes. These treatment processes generate biogas which can be used as a renewable energy sources. Recently, anaerobic digestion of solid wastes has attracted more interest because of current environmental problems, most especially those concerned with global warming. Thus, laboratory-scale research on this area has increased significantly. In this study, the production of biogas from solid wastes according to its origin via various anaerobic technologies was presented. Food, agriculture, garbage and chicken manure were investigated for producing biogas production under mesophlilc conditions. Animal manure was added as a starter to facilitate the anaerobic digestion process. The obtained results show that, the biogas produced ranged between 23.32.to50.11.L/L. The highest biogas yield was observed with chicken manure waste to50.11.L/L compared to other wastes.

Promoting circular economy in the surroundings of an organic fraction of municipal solid waste anaerobic digestion treatment plant: Biogas production impact and economic factors

The Anaerobic Digestion and Composting Plant of the Vallès Oriental Waste Treatment Centre processes source-selected organic fraction of municipal solid wastes generated in its surrounding area. To promote Circular Economy between Municipal Solid Waste and industrial waste management systems, the Treatment Centre is looking for complementary wastes to be valorised through co-digestion with its main substrate. The study includes waste characterization and a complete treatment cost analysis, that jointly with the biogas potential and the mass balance of the Plant allows to calculate the price of each waste to be treated in the Plant. Up to 13 industrial wastes have been characterised for its biogas potential and its treatment cost calculated. Treatment prices ranged between 83 and 51 € t−1.

Penta- and 2,4,6-tri-chlorophenol biodegradation during municipal solid waste anaerobic digestion

In this study isotopic tracing using 13C labelled pentachlorophenol (PCP) and 2,4,6-trichlorophenol (2,4,6-TCP) is proposed as a tool to distinguish the loss of PCP and 2,4,6-TCP due to biodegradation from other physical processes. This isotopic approach was applied to accurately assess in situ PCP and 2,4,6-TCP degradation under methanogenic conditions in several microcosms made up of household waste. These microcosms were incubated in anaerobic conditions at 35°C (mesophilic) and 55°C (thermophilic) without agitation. The volume of biogas produced (CH4 and CO2), was followed for a period of 130 days. At this stage of stable methanogenesis, 13C6-PCP and 13C6-2,4,6-TCP were introduced anaerobically in microcosms and its monitoring at mesophilic and thermophilic conditions was performed in parallel by gas chromatography mass spectrometry (GC–MS) and gas chromatography isotope-ratio mass spectrometry (GC–IRMS). This study proved the almost total dechlorination of bioavailable PCP and 2,4,6-TCP into 4-CP at 35°C. Nevertheless, high rate adsorption in particular materials of the two compounds was observed. Furthermore, Carbon-13 Nuclear Magnetic Resonance (13C-NMR) Spectroscopy analysis of 13C labelled 2,4,6-TCP mesophilic incubations showed the partial mineralization of 4-CP at 35°C to acetate and then to HCO3−. Consequently, NMR results confirm the biogas isotopic results indicating the mineralization of 13C labelled 2,4,6-TCP into 13C (CH4 and CO2). Concerning 13C labelled PCP mesophilic incubations, the isotopic composition of the biogas still natural until the day 262. In contrast, no dechlorination was observed at 55°C. Thus PCP and 2,4,6-TCP were persistent in thermophilic conditions.

Mathematical Modeling and Simulation of Anaerobic Digestion of Solid Waste

Waste management and energy crisis are the greatest issues that the world is facing today. This problem can be overcome by anaerobic digestion of solid waste, where the waste is converted to biogas: a mixture of mainly carbon dioxide and methane gas. Because of the growing need of anaerobic digestion of solid waste, increased efforts in reducing biogas plant design cost and optimizing process operation is crucial. One way of doing this can be through mathematical modeling of the anaerobic process. The purpose of this paper is to use the Anaerobic Digestion Model no.1 (ADM1), which gives complete information about the physico-chemical reactions in the anaerobic process, to investigate how different parameters in the model affect biogas production. A model was implemented in MATLAB and can be used to find out how the factors such as pH and Volatile Fatty Acid (VFA) affect the daily biogas production.

Environmental impact of rejected materials generated in organic fraction of municipal solid waste anaerobic digestion plants: Comparison of wet and dry process layout

Anaerobic digestion of source separated organic fraction of municipal solid waste is an increasing waste valorization alternative instead of incineration or landfilling of untreated biodegradable wastes. Nevertheless, a significant portion of biodegradable wastes entering the plant is lost in pre-treatments and post-treatments of anaerobic digestion facilities together with other improper materials such as plastics, paper, textile materials and metals. The rejected materials lost in these stages have two main implications: (i) less organic material enters to digesters and, as a consequence, there is a loss of biogas production and (ii) the rejected materials end up in landfills or incinerators contributing to environmental impacts such as global warming or eutrophication.The main goals of this study are (i) to estimate potential losses of biogas in the rejected solid materials generated during the pre- and post-treatments of two full-scale anaerobic digestion facilities and (ii) to evaluate the environmental burdens associated to the final disposal (landfill or incineration) of these rejected materials by means of Life Cycle Assessment.This study shows that there is a lost of potential biogas production, ranging from 8% to 15%, due to the loss of organic matter during pre-treatment stages in anaerobic digestion facilities. From an environmental point of view, the Life Cycle Assessment shows that the incineration scenario is the most favorable alternative for eight out of nine impact categories compared with the landfill scenario. The studied impact categories are Climate Change, Fossil depletion, Freshwater eutrophication, Marine eutrophication, Ozone depletion, Particulate matter formation, Photochemical oxidant formation, Terrestrial acidification and Water depletion.

Contribution of acetic acid to the hydrolysis of lignocellulosic biomass under abiotic conditions

Acetic acid was used in abiotic experiments to adjust the solution pH and investigate its influence on the chemical hydrolysis of the Organic Fraction of Municipal Solid Waste (OFMSW). Soluble chemical oxygen demand (SCOD) was used to measure the hydrolysis under oxidative conditions (positive oxidation–reduction potential values), and pH 4 allowed for 20% (±2%) of the COD added to be solubilized, whereas only 12% (±1%) was solubilized at pH7. Under reducing conditions (negative oxidation–reduction potential values) and pH 4, 32.3% (±3%) of the OFMSW was solubilized which shows that acidogenesis at pH 4 during the anaerobic digestion of solid waste can result in chemical hydrolysis. In comparison, bacterial hydrolysis resulted in 54% (±6%) solubilization.

Anaerobic digestion of solid waste in RAS: effect of reactor type on the biochemical acidogenic potential (BAP) and assessment of the biochemical methane potential (BMP) by a batch assay

Anaerobic digestion is a way to utilize the potential energy contained in solid waste produced in recirculating aquaculture systems (RASs), either by providing acidogenic products for driving heterotrophic denitrification on site or by directly producing combustive methane. In this study the biochemical acidogenic potential of solid waste from juvenile rainbow trout was evaluated by measuring the yield of volatile fatty acids (VFA) during anaerobic digestion by batch or fed-batch reactor operation at hydrolysis time (HT)/hydraulic retention time (HRT) of 1, 5, or 10 days (and for batch additional 14 and 20 days) in continuously stirred tank reactors. Generally, the VFA yield increased with time and no effect of the reactor type used was found within the time frame of the experiment. At 10 days HT or 10 days HRT the VFA yield reached 222.3±30.5 and 203.4±11.2mgVFAg−1TVS0 (total volatile solids at day 0) in batch and fed-batch reactor, respectively. For the fed-batch reactor, increasing HRT from 5 to 10 days gained no significant additional VFA yield. Prolonging the batch reactor experiment to 20 days increased VFA production further (273.9±1.6mgVFAg−1TVS0, n=2). After 10 days HT/HRT, 16.8–23.5% of total Kjeldahl N was found as TAN and 44.3–53.0% of total P was found as ortho-phosphate. A significant difference between reactor types was detected for the phosphorous dissolution at 5 days HT/HRT as a relatively steep increase (of a factor 2–3) in ortho-P content occurred in fed-batch reactors but similar steep increase was only notable after 10 days HT for batch reactors. No differences between reactor types at the other HT/HRT were recorded for P as well as (for all HT/HRT for) N. Based on this study a HRT of approximately 5 days would be recommended for the design of an acidogenic continuously stirred reactor tank in a RAS single-sludge denitrification set-up. The biochemical methane potential of the sludge was estimated to 318±29gCH4g−1TVS0 by a batch assay and represented a higher utility of the solid waste when comparing the methane yield with the VFA yield (in COD units). This points toward a technological challenge of ultimately increase the acidogenic output to match the methane yield as both products are formed from the same source.

Biogas Harvesting from Organic Fraction of Municipal Solid Waste as a Renewable Energy Resource in Malaysia: A Review

The accumulation of organic fraction in municipal solid waste (OFMSW) is now becoming scarce globally due to population and economic boosts, especially in Malaysia. Municipal solid waste (MSW) landfills remain the predominant end-state for waste disposal in most developing countries. Unsustainable MSW management accelerates environmental degradation through landfill gaseous (LFG) emissions of mainly methane (CH4) and carbon dioxide (CO2), which promote global warming that finally is affecting human health. Recently, harnessing CH4 from anaerobic digestion of solid waste has attracted more interest and promised betterment in MSW management. With its current amount of more than 50%, organic material in landfills is estimated to emit 310,225 CH4/year with carbon credit of US$ 85.93, which can potentially generate 2.20×10 9 kWh of electricity valued at US$ 220 million. This present work is a review manuscript that discusses the state-of-the-art anaerobic digestion of OFMSW as treatment in term of waste diversion from a landfill. The study also estimates the renewable energy potentials from OFMSW waste diversion. Finally, this paper discusses the benefits of harnessing biogas from the perspectives of environmental benefits, energy recovery, and economics.

Evaluation of the 5 and 8 pH point titration methods for monitoring anaerobic digesters treating solid waste

Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness.

Anaerobic digestion of municipal solid waste composed of food waste, wastepaper, and plastic in a single-stage system: Performance and microbial community structure characterization

The performance of municipal organic solid waste anaerobic digestion was investigated using a single-stage bioreactor, and the microbial community structures were characterized during the digestion. The results showed that the biogas and methane production rates were 592.4 and 370.1L/kg with volatile solid added at the ratio of 2:1:1 for food waste, wastepaper, and plastic based on dry weight. The methane volume concentration fluctuated between 44.3% and 75.4% at steady stage. Acetic acid, propionic acid, and butyric acid were the major volatile fatty acids produced during the digestion process. The anaerobic process was not inhibited by the accumulation of ammonia and free ammonia. The bacterial community was found to consist of at least 21 bands of bacteria and 12 bands of archaea at the steady state. All of the results indicated that the mixture of food waste, wastepaper, and plastic could be efficiently co-digested using the anaerobic digestion system.

Measurement of diffusion coefficients in dry anaerobic digestion media

Dry anaerobic digestion of solid wastes is now commonly used at the industrial scale. Dry solid content in waste material is usually higher than 15%. w/w in these processes most industrial technologies in dry modes are not mixed, or sometimes intermittently mixed. In these situations convective transfer is negligible and diffusive transfer predominates and controls the mobility of soluble substrates within the digestion media. However, no data specifically related to diffusive phenomena in dry anaerobic digestion media (digestate) can be found in the literature. In the present study, an innovative experimental method was developed to determine diffusion coefficients experimentally. This method was based on the use of a specifically designed diffusion cell where iodide was used as a soluble tracer. The influence of total solid (TS) content on diffusion coefficients in digestate material was then investigated. Experimental results showed a strong influence of TS content. It was found that the effective diffusion coefficient (Deff) decreased drastically when TS content increased, with numerical values 50 to 185 times smaller at 8% TS and 25% TS, respectively than the reference value in water. This observation was probably due to the huge increase of viscosity within this range of dry solid content.

Sonolysis and ozonation as pretreatment for anaerobic digestion of solid organic waste

This study aims to compare the efficiency of sonolysis and ozonation in improving anaerobic biodegradability of source sorted organic fraction of municipal solid waste, for the enhancing of biogas production and energy recovery as well. The methane yield of solid organic material anaerobic digestion is significantly affected by substrate availability, which can be favoured by pretreatments. In this investigation, both sonolysis and ozonation effects on substrate solubilisation and anaerobic biodegradability were evaluated under different treatment conditions. Results show that both pretreatments can significantly improve the solubilisation of organic solid waste. However, during ozonation experiments, no correlation was observed between increased solubilisation and biogas production: the application of higher ozone doses led to the formation of by-products less biodegradable than untreated substrate. This evidence makes the ultrasound process more efficient than ozonation and addresses further studies for sonolysis optimisation as pretreatment for solid waste anaerobic digestion.

Evaluation of biodegradability of phenol and bisphenol A during mesophilic and thermophilic municipal solid waste anaerobic digestion using 13C-labeled contaminants

In this paper, the isotopic tracing using 13C-labeled phenol and bisphenol A was used to study their biodegradation during anaerobic digestion of municipal solid waste. Microcosms were incubated anaerobically at 35°C (mesophilic conditions) and 55°C (thermophilic conditions) without steering. A continuous follow-up of the production of biogas (CH4 and CO2), was carried out during 130d until the establishment of stable methanogenesis. Then 13C12-BPA, and 13C6-phenol were injected in microcosms and the follow-up of their degradation was performed simultaneously by gas chromatography isotope-ratio mass spectrometry (GC–IRMS) and gas chromatography mass spectrometry (GC–MS). Moreover, Carbon-13 Nuclear Magnetic Resonance (13C-NMR) Spectroscopy is used in the identification of metabolites. This study proves that the mineralization of phenol to CO2 and CH4 occurs during anaerobic digestion both in mesophilic and thermophilic conditions with similar kinetics. In mesophilic condition phenol degradation occurs through the benzoic acid pathway. In thermophilic condition it was not possible to identify the complete metabolic pathway as only acetate was identified as metabolite. Our results suggest that mineralization of phenol under thermophilic condition is instantaneous explaining why metabolites are not observed as they do not accumulate. No biodegradation of BPA was observed.

Production of biogas from solid organic wastes through anaerobic digestion: a review

Anaerobic digestion treatments have often been used for biological stabilization of solid wastes. These treatment processes generate biogas which can be used as a renewable energy sources. Recently, anaerobic digestion of solid wastes has attracted more interest because of current environmental problems, most especially those concerned with global warming. Thus, laboratory-scale research on this area has increased significantly. In this review paper, the summary of the most recent research activities covering production of biogas from solid wastes according to its origin via various anaerobic technologies was presented.