Anaerobic Digestion Of Organic Fraction Research Articles

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.

Optimizing anaerobic digestion of organic fraction of municipal solid waste (OFMSW) by using biomass ashes as additives

The purpose of this study is to test alternative additives for trace element (TE) supplementation and process stabilization during anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) and sewage sludge. Process instabilities due to acidification are a typical problem in waste fermentation. Provision with minerals and TE is crucial for microorganisms in AD to work effectively, allowing higher organic loading rates within the digester without risking acid accumulation. In batch-fermentation tests, different mixture configurations of OFMSW, digested sewage sludge and biomass ashes were evaluated. Based on an extensive characterization of the TE contained in wood ashes, suitable combinations of digested sewage sludge and OFMSW as a baseline substrate together with ash additives were derived. While high dosages of ash reduced biogas production, 1:1 mix of ash and OFMSW facilitated higher CH4 yields (6%). The supplementation of ashes increased the pH-value within AD and CO2 precipitation through metal oxides in situ elevated the CH4 concentration in biogas up to 98%. Therefore, ashes may increase the efficiency of AD and serve as a basis for a new gas purification method, minimizing technical effort. Additional investigations are needed to examine long-term effects as well as financial and legal aspects such as possible ways of digestate usage. As a further area of research, the transferability of batch-test results into practical applications is identified.

Effects of woody biochar on dry thermophilic anaerobic digestion of organic fraction of municipal solid waste

This study presents the results of semi-pilot scale anaerobic digestion tests conducted under dry thermophilic conditions with the addition of biochar (6% on fresh mass basis of inoculum), derived from an industrial gasification plant, for determining biogas and biomethane production from organic fraction of municipal solid waste. By using two types of inocula (from a full-scale dry anaerobic digestion plant and from lab-scale biomethanation tests), the obtained experimental results did not show significant increase in methane yield related to the presence of biochar (330.40 NL CH4 kgVS−1 using plant inoculum; 335.41 NL CH4 kgVS−1 using plant inoculum with biochar, 311.78 NL CH4 kgVS−1 using lab-inoculum and 366.43 NL CH4 kgVS−1 using lab-inoculum with biochar), but led to significant changes in the microbial community composition. These results are likely related with the specific biochar physical-chemical features and low adsorption potential.Resulting digestate quality was also investigated: biochar-enriched digestates were characterized by increased biological stability (809 ± 264 mg O2 kgVS−1 h−1 vs. 554 ± 76 mg O2 kgVS−1 h−1 for biochar-free and biochar-enriched digestates, respectively), lower heavy metals concentrations (with the exception of Cd), but higher polycyclic aromatic hydrocarbons content, with a reported maximum concentration of 8.9 mgPAH kgTS−1 for biochar-enriched digestate derived from AD test with lab-inoculum, which could trigger non-compliance with regulation limits for agricultural reuse of digestates. However, phytotoxicity assessments showed a decreased toxicity of biochar-containing digestates when compared to biochar-free digestates.

Mesophilic and Thermophilic Anaerobic Digestion of Organic Fraction Separated during Mechanical Heat Treatment of Municipal Waste

The objective of this study was to investigate the effect of process temperature on semi-continuous anaerobic digestion of the organic fraction separated during autoclaving of municipal waste. Tests were carried out in reactors with full mixing. Biogas production was higher in thermophilic conditions than in mesophilic conditions (0.92 L/g volatile solids at 55 °C vs. 0.42 L/g volatile solids at 37 °C, respectively). The resulting methane yields were 0.25-0.32 L CH4/g VS and 0.56–0.70 L CH4/g VS in mesophilic and thermophilic conditions, respectively. In both variants, the methane share was over 70% v/v. This work also discusses the potential impact of Maillard compounds on the efficiency of the fermentation process, which were probably produced during the process of autoclaving of municipal waste. These results indicate that, after autoclaving, the organic fraction of municipal waste can be an effective substrate for anaerobic digestion in thermophilic conditions.

Pathogen Reduction Potential in Anaerobic Digestion of Organic Fraction of Municipal Solid Waste and Food Waste.

Anaerobic digestion (AD) is a commonly used method of processing waste. Regardless of the type of the used digestate (fertilizer, feedstock in case of solid-state fermentation, raw-material in case of thermal treatment) effective pathogen risk elimination, even in the case of high pathogen concentration is essential. An investigation of the survival time and inactivation rate of the Salmonella Senftenberg W775, Enterococcus spp., and Ascaris suum eggs during thermophilic anaerobic digestion performed on laboratory scale and confirmation of hygienization in full-scale operation were performed in this study. Except for sanitization efficiency, the AD process performance and stability were also verified based on determination of pH value, dry matter content, acidity, alkalinity, and content of fatty acids. The elimination of pathogen was met within 6.06 h, 5.5 h, and about 10 h for the Salmonella Senftenberg W775, Enterococcus spp., and Ascaris suum, respectively in the laboratory trials. The obtained results were confirmed in full-scale tests, using 1500 m3 Kompogas® reactors, operating in MBT Plant located in Poland. Sanitization of the digestate was achieved. Furthermore, the process was stable. The pH value, suspended solids, and ammonium content remained stable at 8.5, 35%, and 3.8 g/kg, respectively. The acetic acid content was noted between almost 0.8 and over 1.1 g/kg, while the concentration of propionic acid was noted at maximum level of about 100 mg/kg. The AD conditions could positively affect the pathogen elimination. Based on these results it can be found that anaerobic digestion under thermophilic conditions results in high sanitation efficiency.

Energy from municipal solid wastes: Galati city case study

The municipal solid wastes (MSW) can be turned into resources through recycling and energy recovery. To obtain the maximum amount of energy, the appropriate technology must be applied to waste treatment. The composition and characteristics of municipal solid wastes are determinant for technologies choice for MSW in a city/region. Municipal authorities from the Galati city proposed a recovery rate of recyclable materials of 60% from MSW and treatment of the post-recycling MSW as follow: biodegradable fraction by anaerobic digestion and the combustible fraction by incineration or gasification. In this study traditional and innovative waste to energy technologies have been analysed and the potential of electrical energy of waste has been estimated. Results show that plasma gasification system of raw MSW coupled with gas turbine engine has almost the same electrical energy production (32.92 GWh/year) as conventional gasification of combustible material from MSW (17.21GWh/year) coupled with anaerobic digestion of organic fraction of MSW (11.65 GWh/year). By recovering and using the landfill gas from the Tirighina landfill, 6.68 GWh of electricity can be produced annually.

Enzymatic pre-hydrolysis of organic fraction of municipal solid waste to enhance anaerobic digestion

Enzymatic pretreatment was proposed to enhance the anaerobic digestion of Organic Fraction of Municipal Solid Waste (OFMSW). Enzyme cocktails were produced at laboratory scale from Aspergillus niger fermentation on wheat bran (WB) and OFMSW. The effect of enzyme load, reaction time and agitation speed on OFMSW hydrolysis was determined. Results showed that enzymatic hydrolysis of OFMSW improved organic matter solubilisation. Indeed, pretreatment of OFMSW using WB and OFMSW cocktails resulted respectively in 37.1 and 34.6% change of the soluble chemical oxygen demand and 50 and 40.6% change of the reducing sugars.Anaerobic digestion tests showed that enzyme-treated OFMSW yielded higher biomethane production than raw OFMSW. After hydrolysis by WB and OFMSW cocktails, methane potential of OFMSW increased from 189.2 mL gVS−1 to around 607 and 672 mL gVS−1, respectively. The result confirmed that the use of enzyme cocktails derived from raw waste bioconversion could be a valuable approach to improve biomethane potential of organic wastes.

Acclimatization contributes to stable anaerobic digestion of organic fraction of municipal solid waste under extreme ammonia levels: Focusing on microbial community dynamics

The organic fraction of municipal solid waste (OFMSW) is an abundant and sustainable substrate for the anaerobic digestion (AD) process, yet ammonia released during OFMSW hydrolysis could result in suboptimal biogas production. Acclimatized ammonia tolerant microorganisms offer an efficient way to alleviate ammonia inhibition during AD. This study aimed to achieve an efficient AD of OFMSW under extreme ammonia levels and elucidate the dynamics of the acclimatized microbial community. Thus, two mesophilic continuous stirred tank reactors (CSTR), fed only with OFMSW, were successfully acclimatized up to 8.5 g NH4+-N/L, and their methane yields fluctuated <10%, compared to the methane yields without ammonia addition. Microbiological analyses showed that Methanosaeta concilii and Methanosarcina soligelidi were the dominant methanogens at low and high ammonia levels, respectively. Whilst, a unique metabolic pathway shift, from aceticlastic to hydrogenotrophic methanogenesis, of M. soligelidi was identified during the acclimatization process.

Pilot Plant Data Assessment in Anaerobic Digestion of Organic Fraction of Municipal Waste Solids

In this paper, a preliminary study of anaerobic digestion of organic fraction of municipal solid wastes (OFMSW) in presented with the aim to compare the performances of both wet- and dry-type reactors. The treatment of OFMSW via anaerobic digestion (AD) producing biogas is a process that is receiving a growing interest because two different needs can be coupled: the request of sustainable municipal waste treatments and increasing demand renewable energy. This paper aims to offer experimental results comparing batch test and continuous experimental reactors under different conditions of humidity and solid content. Results show that both the investigated configurations may be used for converting OFMSW into a high quality biogas and that the increase of dry matter in the continuous process still allows to achieve significant biogas production rates. A slight reduction of the methane content was observed (less than 5% relative) that can be also related to the change in the level of volatile fatty acids. These results are very promising in supporting the possibility of operating an industrial scale plant with a dry-process without affecting the system performance.

Organic Fraction of Municipal Solid Waste: Overview of Treatment Methodologies to Enhance Anaerobic Biodegradability

Organic fraction of municipal solid waste and its proper disposal is becoming a serious challenge around the world. Environmental pollution, public health risk, and scarcity of dumping land are the aftereffects of its improper disposal. Embodied energy recovery associated with the organic waste along with waste minimization may be achieved using anaerobic digestion. The chemical composition of the substrate plays a crucial role among the factors responsible for digestion performance and cumulative methane production. Treatment of substrate to enhance the digestion performance is gaining momentum in the recent years. This review provides an overview of different treatment methodologies including mechanical, thermal, chemical, biological, ultrasonic, and microwave approaches to enhance methane yield of anaerobic digestion of organic fraction of municipal solid waste (OFMSW). Environmental impact analysis of treatment techniques, along with comparison of treatment methodologies and techno-economic assessment, have also been discussed to provide a proper insight into the various processing methods.

Effect of phenolic compounds on hydrogen production from municipal solid waste

The present study evaluates the effect of phenolic inhibitors viz. m-cresol, pentachlorophenol, bisphenol-A, and catechol on hydrogen production from anaerobic digestion of organic fraction of the municipal solid waste. Various concentration range of phenolic compounds (0.5, 2.5, 5.0, 10 and 25 mg/L) was applied. The results revealed that the inhibition coefficient of pentachlorophenol was highest among all the inhibitors resulting in lowest hydrogen production and yield. In control, the cumulative hydrogen production was 227.9 ± 10.5 mL which declined to a minimum of 93.4 ± 10.1 mL, 36.4 ± 10.1 mL, 58.9 ± 10.4 mL and 85.8 ± 10.3 mL for experimental batches supplemented with m-cresol, pentachlorophenol, bisphenol-A and catechol respectively. The corresponding decline in the hydrogen yield was 28.0%, 43.8%, 37.1% and 31.8% respectively. Further analysis revealed that inhibitors were completely removed up to a concentration not exceeding 0.25 mg/L. However, at higher concentrations, inhibitors removal efficiency was declined. COD removal efficiency was also negatively affected by inhibitors.

Life-cycle assessment of solid-waste management in city of Zagreb, Croatia

In terms of improvement of the existing municipal solid-waste management system in city of Zagreb (Croatia) in a line with legal requirements and its shift towards circular economy, two scenarios were investigated. Life-cycle assessment (LCA) methodology was used to compare the existing municipal solid-waste management system mainly relay on landfilling of waste with expanded system combining mechanical separation of recyclable fractions of mixed municipal waste (MMW), anaerobic digestion of organic fraction, and thermal treatment of residual waste. The waste management-dedicated LCA software EASETECH was used for the assessment of the scenarios in accordance with the EDIP 1997 LCA method. Improved solid-waste management scenario showed superior results in terms of increased recycling rate of valuable materials and overall environmental performance. Because of introduction of convenient mechanical, biological, and thermal treatment technologies, it enables fulfilment of legal obligation concerning waste recycling targets and landfilling of waste.

Anaerobic digestion of organic fraction from hydrothermal liquefied algae wastewater byproduct

The wastewater stream from hydrothermal liquefaction (HTL) process used in biofuel production, contains a large amounts of organic compounds where several can be regarded as environmentally hazardous and requires significant treatment before disposal. In this study, semi-continuous anaerobic digestion is used to degrade the organic fraction of wastewater streams from HTL of the algae Tetraselmis (AgTet) and Chlorella (AgChlr). Results indicated high methane yields at 20–30% (v/v) HTL wastewater together with clarified manure, producing 327.2mL/gVSin (or volatile solids in feed) for AgTet and 263.4mL/gVSin for AgChlr. There was a significant reduction in methane production at concentrations higher than 40% (v/v) HTL wastewater in the feed, possibly due to the accumulation of chloride salts or inhibitory compounds such as pyridines, piperidines and pyrrolidines. This was further confirmed by comparing COD, salt and the ammonia concentrations of the effluents after anaerobic digestion at different concentrations of wastewater in manure.

Fe3O4 nanoparticles facilitated anaerobic digestion of organic fraction of municipal solid waste for enhancement of methane production

ABSTRACTSince the emergence of zero waste concept, efficient waste recycling system and recovery of energy from the waste materials become challenging tasks globally. Municipal solid waste (MSW) is considered as one of a potential sources of energy. In the present study, bio-compactable iron oxide (Fe3O4) nanoparticles (NPs) were synthesized by hydrothermal method. These NPs were characterized by using atomic force microscopy (AFM), energy dispersive x-ray (EDX), and scanning electron microscopy (SEM) for size determination and surface morphology. The organic fraction of MSW (OFMSW) such as food waste (FW) was utilized as a substrate in this study. The anaerobic digestion of OFMSW in batch test was carried out under mesophilic temperature (37 ± 0.5°C). Four different concentrations of Fe3O4 NPs i.e 50mg/L, 75mg/L, 100mg/L, and 125mg/L were added in each batch test. It was observered that 75mg/L yielded maximum CH4 and followed by 50mg/L.

The toxicity effects of ammonia on anaerobic digestion of organic fraction of municipal solid waste

In this research the inhibitory effects of ammonia on the AD of synthetic OFMSW were examined under different total ammonia nitrogen (TAN) concentrations of 2,500, 5,000, 7,500, and 10,000mg/L and at pH levels of 7.5, 8.0 and 8.5 using a factorial experimental design and statistical analysis. Reduction in Cumulative Biogas Production (CBP) at a TAN concentration of 2,500mg/L was close to 10% for all 3 pH levels. For a TAN concentration of 10,000mg/L the percent reduction in CBP was over 80% for all 3 pH levels showing significant inhibition due to ammonia with neglible influence due to change in pH. However, pH played a more significant role for TAN concentrations between the above two levels, as at a TAN concentartion of 7,500mg/L, the percent reduction in CBP increased from 42.2% at a pH of 7.5 to 76.5% at a pH of 8.5. Regression analysis was used to estimate CBP and % reduction (%R) in CBP using a quadratic equation with pH and TAN as independant variables (R2=0.95 and 0.94). Methane produciton per g of COD removed was obsereved to vary from 264mL CH4/g CODd for control reactors at pH 7.5 down to 1mL CH4/g CODd for the reactor at pH of 8.5 which contained 10,000mg/L TAN. Results of gradual ammonia loading also showed that mesophilic bacteria could be adapted to a TAN concentration of up to 5,000mg/L at pH 7.5 through gradual TAN loading. At 10,000mg/L TAN CBP in reactors with gradual TAN loading was more than 1.9–3 times the CBP in reactors with abrupt TAN addition.

Effect of inoculum source on anaerobic digestion of organic fraction of municipal solid waste in Mexico

This study investigates the use of electrohydrolysis pretreatment on water hyacinth to cut short the hydrolysis step and increase biogas production at the same time. Electrohydrolysis pretreatment of water hyacinth at 20 V for 60 min exhibited improved solubilisation (42.9%). Therefore, bio-chemical methane potential (BMP) test was carried out between water hyacinth pretreated at 20 V for 60 min and untreated water hyacinth. By the end of 30 days, cumulative methane production of 2455 ± 17 mL CH4/g VS for electrohydrolysis pretreated substrate and 1936 ± 27 mL CH4/g VS for the untreated substrate was achieved. Compositional analysis and characterization study revealed the efficiency of electrohydrolysis pretreatment in melting the lignin and lowering the cellulose crystallinity of water hyacinth.

Effect of control of pH in anaerobic digestion of organic fraction of municipal solid waste

Anaerobic digestion often encounters the problem of higher population of the acid-forming bacteria relative to the slower growing methanogenic bacteria which inhibits the methanogenic process leading to problems such as low gas yield and process instability. In this study, anaerobic digestion of organic fraction of municipal solid waste has been carried out in two identical model laboratory-scale single stage anaerobic digesters simultaneously; one without the control of pH and other with the control of pH, with same substrate keeping all other conditions identical. Results indicated that the hydraulic retention time of AD reaction could be reduced by at least seven days and the overall efficiency of gas production of the digester could be increased by more than 21.95% (at 50 days time) by the control of pH in the digester.

Effect of control of pH in anaerobic digestion of organic fraction of municipal solid waste

Effect of control of pH in anaerobic digestion of organic fraction of municipal solid waste