Anaerobic Digestion Of Organic Fraction Research Articles

Wet anaerobic digestion of organic fraction of municipal solid waste: experience with long-term pilot plant operation and industrial scale-up

This paper presents the analysis of a pilot anaerobic digestion plant that operates with organic fraction of municipal solid waste (OFMSW) from a wholesale market and can treat up to 500 kg d−1. The process was monitored for a period of 524 days during which the residue was characterized and the biogas production and methane content were recorded. The organic load rate (OLR) of volatile solids (VS) was 0.89 kg m−3 d−1 and the Hydraulic Retention Time (HRT) was 25 d during the process. The yield was 82 Nm3 tons OFMSW−1 biogas, equivalent to 586 Nm3 tons CH4 VS−1. The results obtained in the pilot plant were used to carry out a technical–economic evaluation of a plant that treats 50 tons of OFMSW from wholesale markets. A production of 3769 Nm3 d−1 of biogas and 2080 Nm3 d−1 of methane is estimated, generating 35.1 MWh d−1 when converted to electricity.

Electronic regulation to achieve efficient anaerobic digestion of organic fraction of municipal solid waste (OFMSW): strategies, challenges and potential solutions

Anaerobic digestion (AD) of organic fraction of municipal solid waste (OFMSW) is prone to system breakdown under high organic loading rates (OLRs) condition, which subsequently reduces the efficiency of digestion process and results in substantial economic losses. In this perspective paper, the substances metabolisms, electrons flow, as well as microbial interaction mechanisms within AD process are comprehensively discussed, and the underlying bottleneck that causes inefficient methane production is identified, which is “electrons surplus”. Systems encountering severe electron surplus are at risk of process failure, making it crucial to proactively prevent this phenomenon through appropriate approaches. On this basis, the present perspective proposes three potential electronic regulation strategies to prevent electrons surplus, namely, electron shunt, accelerating electron transfer and regulating methanogenic metabolism pathway, and presents specific methodologies for each strategy. Furthermore, the potential solutions to challenges that may occur during the electronic regulation process are also presented in this paper. This perspective aims to provide innovative approaches to achieve the efficient and stable operation of OFMSW anaerobic digestion, especially under high OLRs condition.

Mass Transfer Enhancement in High-Solids Anaerobic Digestion of Organic Fraction of Municipal Solid Wastes: A Review.

The increasing global population and urbanization have led to a pressing need for effective solutions to manage the organic fraction of municipal solid waste (OFMSW). High-solids anaerobic digestion (HS-AD) has garnered attention as a sustainable technology that offers reduced water demand and energy consumption, and an increased biogas production rate. However, challenges such as rheology complexities and slow mass transfer hinder its widespread application. To address these limitations, this review emphasizes the importance of process optimization and the mass transfer enhancement of HS-AD, and summarizes various strategies for enhancing mass transfer in the field of HS-AD for the OFMSW, including substrate pretreatments, mixing strategies, and the addition of biochar. Additionally, the incorporation of innovative reactor designs, substrate pretreatment, the use of advanced modeling and simulation techniques, and the novel conductive materials need to be investigated in future studies to promote a better coupling between mass transfer and methane production. This review provides support and guidance to promote HS-AD technology as a more viable solution for sustainable waste management and resource recovery.

Evaluation and optimization of hydrothermal carbonization condition for hydrochar and methane yield from anaerobic digestion of organic fraction of municipal solid waste (OFMSW)

Effectively converting and utilizing the organic fraction of municipal solid waste is a critical strategy to combat environmental pollution and optimize resource utilization. Responsible handling of waste by-products in an environmentally sustainable manner is essential. The utilization of hydrothermal carbonization and anaerobic digestion are rising as progressive, environmentally sustainable technologies for handling the organic component of municipal solid waste, with the added benefit of energy recuperation. Given distinct experimental objectives, comprehensively investigating the optimal conditions for both hydrothermal carbonization and anaerobic digestion experiments with hydrochar feed poses significant challenges. As a result, this study centers its attention on the hydrochars generated through the hydrothermal carbonization process and their impact on the anaerobic digestion of the organic fraction of municipal solid waste. In the first, the relationship between proximate analysis, ultimate analysis, fuel properties, fiber composition, and methane yield of hydrochars at different conditions (150 ≤ temperature ≤ 230 °C, 20 ≤ retention time ≤ 60 min, and 0.15 ≤ biomass loading ≤ 0.35 g/ml) was evaluated. The content of carbon and hydrogen was increased while the content of oxygen decreased. The hydrothermal carbonization process resulted in an increase in the carbon and hydrogen content, accompanied by a decrease in oxygen content. Moreover, alterations in temperature and retention time during the hydrothermal pretreatment led to variations in the contents of cellulose, hemicellulose, and lignin in the hydrochars. Upon subjecting the hydrochars to anaerobic digestion, the methane yield exhibited a wide range, varying from −51.3 to 61.69% in comparison to the control sample. These outcomes emphasize the significant influence of hydrothermal carbonization conditions on the subsequent anaerobic digestion process, yielding a diverse spectrum of methane production levels. Subsequently, the Response Surface Method, a statistical methodology, was employed to investigate the influence of three parameters. Through this approach, optimal conditions were determined to achieve the maximum hydrochar yield (HC150-20-0.35) at 68.6%, the maximum methane yield (HC168.52-39.47-0.19) at 251.38 ml/g VS, and the simultaneous maximization of hydrochar yield and methane yield (HC159.9-28.75-0.23) at 63.1% and 237.68 ml/g VS, respectively. Finally, the structural and morphological properties of the optimized hydrochars were subjected to thorough analysis.

Anaerobic digestion of organic fraction of municipal solid waste using a novel two-stage solid-liquid system

Organic fraction of municipal solid waste (OFMSW) has high volatile solid and moisture content, which is mainly treated via anaerobic digestion (AD). Since the composition of OFMSW is complicated and inconstant, it is difficult to maintain the AD process stable and effective. In this study, a novel two-stage AD system, including a tank-type acidogenic phase and a fixed-bed methanogenic phase, was implemented for OFMSW treatment to demonstrate the feasibility of the two-stage configuration. Results showed that 84% of potential CH4 yield was achieved and the methane content reached 77.83% on average in methanogenic phase. The acetoclastic methanogens, Methanosaeta and Methanosarcina, which can participate in direct interspecies electron transfer, were the dominant genera in solid digestate and the biofilm. The hydrogenotrophic methanogens, Methanospirillum and Methanoculleus, accounted for high proportions in liquid digestate. Our study provides a novel approach to treat OFMSW with less water consumption, high stability and efficiency.

Effect of inoculum origin and substrate-inoculum ratio to enhance the anaerobic digestion of organic fraction municipal solid waste (OFMSW)

This study evaluated the key role of inoculum in mesophilic anaerobic digestion (AD) of Organic Fraction of Municipal Solid Waste. The effect of two different inocula, the mesophilic digestate of wastewater activated sludge (WAS) and the mesophilic digestate of cow-agriculture sludge (CAS), at three different substrate: inoculum ratios (1:2, 1:1 and 2:1) at three different incubation times (0, 5 and 10 d) were studied in batch feeding reactor for a total of 18 AD configurations. The AD configurations were study through specific biogas and methane productions, first order disintegration kinetics, Gompertz modified study and energy sustainable index. A multi criteria decision aid outranked the 18 AD configurations tested. The study proved that the AD performed with inoculum CAS incubated for 10 d at 2:1 substrate inoculum ratio reached the highest biogas yield and methene content equal to 997.81 NL/kgVS and 70.00% v/v.

Co-digestion of municipal solid waste with lignocellulosic waste in mesophilic Environment

The present study deals with the dual problem of municipal solid waste and lignocellulosic waste in which authors tried to use these two waste materials as clean and renewable energy source. In the present study, anaerobic digestion of organic fraction of municipal solid waste and lignocellulosic waste in varying combinations was carried out. Five-set of experiments (S1, S2, S3, S4, and S5) under mesophilic conditions were conducted in batch reactors. From all the combinations, reactor S3 (organic fraction of municipal solid waste: lignocellulosic waste, 1:1 ratio) was observed to be the best combination producing 70.09 ml concentration of methane out of 78.76 ml of biogas as compared to all other combinations. The increase in methane production rate was observed by 53.67% due to the addition of lignocellulosic waste. The decline in methane production at the end of the 50th day was observed due to a fall in pH, which created acidic conditions, thus inhibiting the conversion process. It was found that the mesophilic condition acted as a governing factor in the process of digestion.

Use of Inoculum, Water and Percolate as Strategy to Avoid Inhibition on Dry-Batch Anaerobic Digestion of Organic Fraction of Municipal Solid Waste

The impact of inoculum to substrate ratio (I:S) and the addition of water and percolate on stopping inhibition in dry batch anaerobic digestion of organic fraction municipal solid waste (OFMSW) was investigated. In particular, ratios of I:S from 1:2 to 1:16 and total solid contents from 40 to 25% with water and percolate addition were analysed. Tested I:S did not avoid acidification of the anaerobic digesters (ADs), and the highest biogas and methane production (16.2 and 1.7 L/kg VSadded, respectively) was achieved with the 1:4 ratio. Water addition was also insufficient to avoid acidification, and while biogas increased as TS decreased, 40.9 L/kg VSadded for 25% TS, methane yield remained low at 1.2 L/kg VSadded due to the inhibition of methanogenic archaea. Percolate addition proved a suitable strategy to increase pH buffering, with an increased methane production of 199.4 L/kg VSadded at similar TS ranges (27%). Impact on kinetics of methane formation was assessed by kinetic modelling with logistic model identified as the better fit for most of the ADs. Shorter lag phases were observed as TS were reduced, regardless of the acidification, as mass transfer limitations were reduced at the beginning of the batch, but an increase was observed when percolate was used instead of water. Increases of the maximum methane rate (Rmax) was also achieved with TS reduction, but only when acidification was avoided. This study has highlighted the need to profile percolate composition during batch digestion in order to balance recirculation of nutrients, microbial communities and toxic compounds.Graphic

High-solids anaerobic digestion of organic fraction of municipal solid waste: Effects of feedstock to inoculum ratio and percolate recirculation time

The effects of feedstock to inoculum (F:I) ratio and percolate recirculation time (PRT) were studied for the high-solids anaerobic digestion (HSAD) of the organic fraction of municipal solid waste (OFMSW). Six mesophilic HSAD systems were operated at different F:I ratios (1 to 3 kg VS/kg VS; PRT = 2.5 h/d) and PRTs (1.5 to 3.5 h/d; F:I = 2 kg VS/kg VS). The F:I ratio of 1 provided up to 86% of the theoretical methane potential of OFMSW. In contrast, F:I ratio of 3 provided only 34% methane recovery due to volatile fatty acids (VFAs) accumulation and pH drop. Despite F:I ratio of 2 could provide 70% methane recovery, it could enable almost 45% higher organics processing capacity (VS basis) and lower solids washout during percolate recirculation, as compared to the F:I ratio of 1. However, different examined PRTs showed marginal impacts on methane yields with comparable changes in profiles of percolate characteristics.

Powdered activated carbon amendment in percolate tank enhances high-solids anaerobic digestion of organic fraction of municipal solid waste

Despite many studies recently investigated the addition of conductive materials for enhancing biomethane recovery in anaerobic digestion, there have been limited efforts to adopt this strategy in high-solids anaerobic digestion (HSAD) with percolate recirculation. In this study, two identical lab-scale mesophilic (36 °C) HSAD systems were operated with the organic fraction of municipal solid waste (OFMSW) under similar operating conditions, including food to microorganism ratio and daily percolate recirculation rate. The percolate tank of the test HSAD system was amended with 15 g/L of powdered activated carbon (PAC). After 30 days of operation, the cumulative biomethane yield for the test reactor was 17 % higher than the control reactor (109 vs. 93 L CH4/kg VS). Furthermore, PAC addition showed additional benefits by lowering free ammonia nitrogen (FAN) and volatile fatty acids (VFAs) concentrations that can inhibit anaerobic digestion. Nonetheless, the preliminary economic analysis suggested that the HSAD amended with PAC is practically challenging and will only be economically feasible if PAC can be recycled and reused for the long-term operation or several cycles.

Municipal solid waste management and economic feasibility for electricity generation from landfill gas and anaerobic reactors in a Brazilian state

This study aims to estimate the potential of the municipal solid waste management consortiums in Minas Gerais for electricity generation from Landfill Gas (LFG) and from anaerobic reactors for organic fractions of this waste. Economic viability studies were conducted for both types of enterprises. Projections for landfill biogas generation were made using the United States Environmental Protection Agency (USEPA) LandGem® 3.02 software program. Estimates for anaerobic digestion of organic fraction of municipal solid waste were performed based on theoretical generation from this substrate’s chemical oxygen demand. The power, electricity, and investment values for both projects were calculated, and the respective Net Present Value (NPV), Internal Rate of Return (IRR), and payback time were also obtained for the various consortiums. The results show that there is economic viability potential for electric energy generation for landfill biogas at the CIAS CENTRO OESTE, CIDES, CISAB Zona da Mata, CONVALE, and CORESAB Boa Vista municipal solid waste consortiums. Electric Energy obtained for the state of Minas Gerais would be about 3,900,000 MWh/year, and the total installed power capacity would be approximately 4500 kW for a Thermal Power Plant (TPP) using LFG for all consortiums. These values were nearly 15,400 MWh/year and 3200 kW for biogas energy derived from the Organic Fraction of Municipal Solid Waste (OFMSW) anaerobic digestion.

Evaluation of the performance of integrated bioreactors for anaerobic digestion of organic wastes to biogas

The evaluation of the performance of an integrated bioreactor was carried out using organic municipal waste as the substrate. The test rig of the coupled bioreactor was designed and fabricated for experimented studies of anaerobic digestion of organic fraction of municipal waste. The first module up-flow bioreactor (UASB), has volume of 76 liter, the second module which was designed as twin in bioreactor with central dispensing unit has a total void volume of 76 liters. The test rig has a control panel which can be switch off and on from the experiment the maximum biogas yield was obtained in OLR3 module 11 with 1577 ml/stp followed by OLR1 module 1 with 1572 ml/stp. The least was noticed from the twin reactor OLR2 module 11 with 895 ml/stp. The accumulative biogas yield and R-values obtained show close agreement between observed and theoretical postulate.

Implementing polyhydroxyalkanoates production to anaerobic digestion of organic fraction of municipal solid waste to diversify products and increase total energy recovery

A simple biorefinery aimed at producing both biomethane (CH4) and polyhydroxyalkanoates (PHAs), was proposed to valorize the organic fraction of municipal solid waste (OFMSW). Anaerobic digestion (AD) was tested at different organic loading rates (OLR-I-II-III) (i.e. 3, 4 and 6 g L−1 d−1, respectively), producing biomethane and volatile fatty acids (VFAs)-rich digestate, the VFAs were then used to produce PHAs. Specific biogas and CH4 production remained similar when adopting different OLRs (biogas of 522–600 NL kg−1 VS and CH4 of 64–67% v/v). VFAs concentrated with OLR increases and their patterns were modified. PHA production was in the range of 117–199 g kg−1 OFMSWTS with the lowest production being associated to different polymer composition.The net energy recovery of this simple biorefinery accounted for 64% of OFMSW energy content, and the PHAs produced represented over 30% of the total energy.

An integer superstructure model to find a sustainable biorefinery platform for valorizing household waste to bioenergy, microbial protein, and biochemicals

In this study, a superstructure-based decision making model is presented to determine the most sustainable biorefining pathway of organic fraction of municipal solid waste, i.e., anaerobic digestion, fermentation for bio-succinic acid and lactic acid recovery, and single cell protein production, as well as the best downstream process for the produced biogas. Based on the possible bioprocess routes created from implied technologies, thirteen scenarios were developed to perform mass and energy balances as well as environmental life cycle assessments. Subsequently, a general superstructure-based multi-criteria decision making model was designed representing possible technologies at each stage of biomass processing and their interconnections. The optimal biorefining route for achieving a sustainability solution was selected based on energetic, economic, and environmental aspects; three objective functions for maximizing energy saving and profitability, and minimizing greenhouse gas emissions. The results achieved in this study demonstrated that the scenario including anaerobic digestion of organic fraction of municipal solid waste coupled with a biological biogas upgrading unit for bio-methanation of biogas into fuel-grade bioCH4 was the most sustainable biorefining route. This scenario led to a greenhouse gas saving of 243.4 kg CO2 eq/t biopulp and a primary energy saving of 4664.77 MJ/t biopulp, creating a profit of 145.41 €/t biopulp. On the contrary, biosuccinic acid production with cogeneration of heat & power and bioCH4 with further use as home cooking fuel found to be the least preference for biowaste valorization. The sensitivity analysis showed that fluctuations in production costs and revenue would not change the rank of scenarios however the profitability of scenarios would change to some extent. The framework presented herein is a promising approach to find the most sustainable biorefining rout out of several technically-possible solutions. Such framework would be even more applicable if other important aspects such as spatio-temporal parameters, policy regulations, market-driven factors, etc. to be included in the decision making process.

Transitions of microbial communities in the solid and liquid phases during high-solids anaerobic digestion of organic fraction of municipal solid waste

This study presents a microbiological diagnosis of a mesophilic high-solids anaerobic digestion (HSAD) system with percolate recirculation. The results demonstrated a significant decrease in microbial diversity in both the solid digestate and the liquid percolate. Also, the digestate from the top and middle sections of the digester had similar diversity, whereas the digestate from the bottom of the tank had a slightly lower diversity. These results suggest that despite percolate recirculation, substrate gradients might have developed across the system. Archaeal communities showed shifts towards known hydrogenotrophic and ammonia-tolerant methanogens (genera Methanocelleus, Methanolinea, Methanosarcina, vadin CA11, etc.), which was a consequence of decreased volatile fatty acids and increased ammonia-nitrogen levels over time. Compared to initial solid and liquid inoculum, the relative abundances of some bacteria (phyla Proteobacteria and Firmicutes) and archaea of the genus Methanosarcina changed between two phases in the opposite direction, indicating a shift of microbes between two phases.

Enhancement of biogas production from organic fraction of municipal solid waste using acid pretreatment

Anaerobic digestion of organic fraction of municipal solid waste (OFMSW) is a potential and economic technique for harnessing bioenergy from Indian municipal solid waste. Pretreatment before anaerobic digestion has been known to improve biodegradability of substrate and enhance biogas production. In this study, the effectiveness of acid pretreatment in enhancing the hydrolysis of complex organic matter and ensuing biogas generation from OFMSW was studied using one strong and one weak acid. Acid pretreatment (pH 6–pH 1) of OFMSW was carried out using hydrochloric acid (HCl) and acetic acid (CH3COOH) for 24 h before batch anaerobic digestion assays with cow dung as inoculum. Increase in biogas yield ranged between 13.2 and 28.9% as compared to untreated OFMSW after pretreatment with HCl, whereas the same varied between 8.2 and 16% in case of CH3COOH pretreatment. The highest biogas yield (389.4 ml/gVS) with methane content of 68.3% was obtained after pretreatment with HCl at pH 3, whereas for CH3COOH, the highest yield (350.2 ml/gVS) with 67.4% methane was observed after pretreatment at pH 1. OFMSW characteristics after each pretreatment step and their variation during the course of anaerobic digestion were also studied. An economic evaluation of all pretreatment scenarios was performed; out of which, pretreatment of OFMSW with HCl at pH 4–pH 6 yielded positive results in terms of net revenue gains.

Calibration of the Anaerobic Digestion Model No. 1 for anaerobic digestion of organic fraction of municipal solid waste under mesophilic condition

Parameters calibration of the Anaerobic Digestion Model No.1 for various substrates at different operating conditions is an essential key to widely increase the practical application of this model. In this study, the Anaerobic Digestion Model No.1 incorporated in the Matlab/Simulink platform was calibrated to simulate a mesophilic lab-scale reactor fed with the organic fraction of municipal solid waste operated at five different organic loading rates with a constant solid retention time of 25 days. The Shannon entropy was applied as a sensitivity index to identify important parameters as five indicators: biogas flow, methane flow, pH, effluent COD and ammonia. The sensitivity analysis revealed that the parameters of biogas flow indicator, with entropy higher than 0.2 dB, could cover all other indicators’ parameters. The 13 important kinetic parameters including maximum specific uptake rate of sugar, propionate, acetate and C4+ (valeric and butyric acids) were estimated using the genetic algorithms. The calibrated parameters were validated with the last 50 days of operation, in which the overloading situation occurred. While the non-calibrated model failed to predict the biogas flow at the overloading situation, the calibrated ADM1 reasonably simulated the decreasing trend of the produced biogas flow. Therefore, the Shannon entropy performed well in recognition of sensitive parameters of the complicated nonlinear ADM1. Nevertheless, there are differences between the simulated and experimental results of pH and effluent COD, which resulted in the decline of accuracy for other products of biogas and methane flow. The cumulative biogas production and average composition of biogas flow were predicted well with rAE of 0.04 and 0.18, respectively.

Datasets on chemical composition and anaerobic digestion of organic fraction of municipal solid waste (OFMSW), digested sewage sludge (inoculum) and ashes from incineration or gasification.

This article contains data on the chemical composition and anaerobic digestion of different residue streams including OFMSW, digested sewage sludge, low-carbon (LC) ashes from incineration subdivided into LC coarse and LC fly ash as well as high-carbon (HC) ashes from gasification subdivided into HC reactor and HC fly ash. All materials were collected in accordance to standard procedures in southern Germany. The data presented in this article include (1) dry matter (2) organic dry matter (3) elemental analysis (4) trace elements and (5) cumulative biogas and CH4 yields. Researchers and waste management companies on lab-/pilot-/industrial-scale can rely on the presented data for classification and comparison of biogenic waste streams. For further discussion, please refer to the scientific article entitled “Optimizing anaerobic digestion of organic fraction of municipal solid waste (OFMSW) by using biomass ashes as additives” [1].

Comparative life cycle environmental impacts of two scenarios for managing an organic fraction of municipal solid waste in Rasht-Iran

Population growth and increasing rapidly expanding urbanization in developing countries have led to an increase in municipal solid waste. Accordingly, the municipal solid waste management is a challenging and revolute issue which requires more informed decision making by authorities and experts from a variety of perspectives. Various methods have been suggested for the treatment of municipal solid waste to solve the problems and challenges. However, environmental sustainability should be considered by decision-makers in different ways. The life cycle assessment as a tool can help authorities and experts in the selection of stability methods of municipal solid waste management. Therefore, the objective of this study is to evaluate and compare two scenarios, namely, composting and anaerobic digestion, for managing the organic fraction of municipal solid waste of Rasht city, Iran from an environmental sustainability perspective. Life cycle assessment was used to evaluate the environmental impact of composting and anaerobic digestion of organic fraction of municipal solid waste. In this study, the functional unit is defined as 100 t municipal solid waste and the system boundaries include all proceedings for municipal solid waste transportation from the city to the end of the production process in each scenario. The results showed that the treatment of organic wastes by the anaerobic digestion scenario compared with the composting scenario leads to a reduction of 66.67% in damage to human health, 47.84% in damage to ecosystem quality, and 89.64% in the climate change. Also, the result represents that the treatment of organic wastes by the anaerobic digestion scenario leads to a redaction 21 times in damage to resources compared with when organic wastes are treated by composting scenario. More specifically, the presented results in this study showed anaerobic digestion scenario owing to the treatment of organic wastes and convert them into value-added material/energy has favorable environmental impacts.

High-Solids Anaerobic Digestion Followed by Ultrasonication of Digestate and Wet-Type Anaerobic Digestion for Enhancing Methane Yield from OFMSW

High-solids anaerobic digestion of organic fraction of municipal solid waste often shows inefficient biomethane recovery due to mass transfer limitations. Consequently, this study presents a two-stage anaerobic digestion process combining high-solids anaerobic digestion followed by ultrasonication of digestate and wet-type anaerobic digestion for effective biomethane recovery from the organic fraction of municipal solid waste. The high-solids anaerobic digestion yielded methane production of 210 L CH4/kg volatile solids (VS). The digestate from the high-solids anaerobic digestion process was ultrasonicated at three different specific energy inputs (1000, 2500, and 5000 kJ/kg total solids (TS)). The increases in the soluble chemical oxygen demand (SCOD) concentrations (8%–32%) and volatile solids (VS) removal efficiencies (3.5%–10%) at different specific energy inputs were linearly correlated (R2 = 0.9356). Thus, ultrasonication led to the solubilization of particulate organics and released soluble organic matters. All ultrasonicated digestate samples showed significantly higher biomethane yields than that observed for the untreated digestate samples. The highest methane yield of 132 L CH4/kg VS was observed for a specific energy input of 5000 kJ/kg TS, which was 1.94 times higher than the control (68 L CH4/kg VS). Although specific energy inputs of 1000 kJ/kg TS and 2500 kJ/kg TS showed comparable methane yields (113–114 L CH4/kg VS), they were ~1.67 times higher than the control. Overall, our results suggest that an integrated system of high-solids and wet-type anaerobic digestion with pre-ultrasonication of digestate has the potential to provide a technically viable solution to enhance biomethane recovery from the organic fraction of municipal solid waste.