Co-digestion Of Organic Wastes Research Articles

Anaerobic Codigestion of Tuber Waste and Fruit Waste: Synergy and Enhanced Biogas Production

Increased urbanization and consumerism have resulted in the excessive release of food waste and municipal solid waste. Such wastes contain abundant organic matter that can be transformed into energy, addressing the twin challenges of waste management and energy insecurity. In recent years, different studies have investigated ways of producing biogas through the codigestion of organic wastes. In this work, different food wastes were codigested and the biogas yield was determined. The effect of feedstock mixing ratios, temperature, and pH was studied. A mixing ratio of 1 : 1 produced the highest biogas yield (2907 ± 32 mL), nearly twice, which was obtained at a ratio of 1 : 4 (1532 ± 17 mL). The biogas yield increased with the temperature rise. The lowest yield of 2907 ± 32 mL was obtained at 20°C, while the highest yield of 4963 ± 54.6 mL was obtained at 40°C. Regarding pH, the yield was 2808 ± 31 mL at pH 6.5 and 7810 ± 86 mL at pH 7.3. This indicated a 178.1% increase in the biogas yield. The CN ratio for tuber waste and fruit waste was 18 and 28, respectively, while the corresponding pH was 6.7 and 6.9. A positive synergy index of 4.5 was obtained, which is higher than what is reported in the literature of codigested substrates. Irish potato peels and banana peels produced the highest biogas yield and are recommended for use as codigested feedstock.

Co-Processing Agricultural Residues and Wet Organic Waste Can Produce Lower-Cost Carbon-Negative Fuels and Bioplastics.

Scalable, low-cost biofuel and biochemical production can accelerate progress on the path to a more circular carbon economy and reduced dependence on crude oil. Rather than producing a single fuel product, lignocellulosic biorefineries have the potential to serve as hubs for the production of fuels, production of petrochemical replacements, and treatment of high-moisture organic waste. A detailed techno-economic analysis and life-cycle greenhouse gas assessment are developed to explore the cost and emission impacts of integrated corn stover-to-ethanol biorefineries that incorporate both codigestion of organic wastes and different strategies for utilizing biogas, including onsite energy generation, upgrading to bio-compressed natural gas (bioCNG), conversion to poly(3-hydroxybutyrate) (PHB) bioplastic, and conversion to single-cell protein (SCP). We find that codigesting manure or a combination of manure and food waste alongside process wastewater can reduce the biorefinery's total costs per metric ton of CO2 equivalent mitigated by half or more. Upgrading biogas to bioCNG is the most cost-effective climate mitigation strategy, while upgrading biogas to PHB or SCP is competitive with combusting biogas onsite.

Two-stage anaerobic membrane bioreactor for co-treatment of food waste and kitchen wastewater for biogas production and nutrients recovery

Co-digestion of organic waste and wastewater is receiving increased attention as a plausible waste management approach toward energy recovery. However, traditional anaerobic processes for co-digestion are particularly susceptible to severe organic loading rates (OLRs) under long-term treatment. To enhance technological feasibility, this work presented a two-stage Anaerobic Membrane Bioreactor (2 S-AnMBR) composed of a hydrolysis reactor (HR) followed by an anaerobic membrane bioreactor (AnMBR) for long-term co-digestion of food waste and kitchen wastewater. The OLRs were expanded from 4.5, 5.6, and 6.9 kg COD m−3 d−1 to optimize biogas yield, nitrogen recovery, and membrane fouling at ambient temperatures of 25–32 °C. Results showed that specific methane production of UASB was 249 ± 7 L CH4 kg−1 CODremoved at the OLR of 6.9 kg TCOD m−3 d−1. Total Chemical Oxygen Demand (TCOD) loss by hydrolysis was 21.6% of the input TCOD load at the hydraulic retention time (HRT) of 2 days. However, low total volatile fatty acid concentrations were found in the AnMBR, indicating that a sufficiently high hydrolysis efficiency could be accomplished with a short HRT. Furthermore, using AnMBR structure consisting of an Upflow Anaerobic Sludge Blanket Reactor (UASB) followed by a side-stream ultrafiltration membrane alleviated cake membrane fouling. The wasted digestate from the AnMBR comprised 42–47% Total Kjeldahl Nitrogen (TKN) and 57–68% total phosphorous loading, making it suitable for use in soil amendments or fertilizers. Finally, the predominance of fine particles (D10 = 0.8 μm) in the ultrafiltration membrane housing (UFMH) could lead to a faster increase in trans-membrane pressure during the filtration process.

Design of a stand‐alone 1000‐kW biogas power plant from codigestion of organic waste and microalgae grown in a tubular photo bioreactor at Bomaka‐Buea

The cover image is based on the Research Article Design of a stand-alone 1000-kW biogas power plant from codigestion of organic waste and microalgae grown in a tubular photo bioreactor at Bomaka-Buea by Fonge Emmanuel Nchindia et al., https://doi.org/10.1049/rpg2.12524.

Design of a stand‐alone 1000‐kW biogas power plant from codigestion of organic waste and microalgae grown in a tubular photo bioreactor at Bomaka‐Buea

Buea is connected to the south interconnected grid (SIG) of Cameroon. But the power supply is unreliable, not accessible to all and of very low quality. In addition, solid municipal waste generated in Buea is poorly collected by Hysacam and dumped at Musaka with no further valorization. There is an acute need to improve on the quantity, reliability and quality of the power supplied to inhabitants of Buea as well as to improve on the environmental management system of the town. In this study a project is proposed to design a stand-alone 1000-kW biogas power plant from the codigestion of organic fraction of solid municipal waste with microalgae (Chorella Sorokiniana) grown in tubular photo bioreactor (PBR) in Bomaka-Buea. As far as electrical energy production is concerned, the aforementioned anaerobic biological treatment unit will produce almost 9311.88 MWh/y. Assuming an average electricity consumption of 3 to 4 MWh/y/household the annual produced electrical energy from the anaerobic digestion (AD) unit could supply almost 3000 to 4000 households in the Municipality of Buea. So by treating the 39% of annual organic waste produced in Buea it can cover between 31.3% and 31.8% of Buea municipality's electrical energy demand. With a levellized cost of electricity at 0.265 $/kW and a net present value of 25.3million dollars if this energy is sold to the national grid then the annual profit of energy production will be around $4,188,888/y (assuming a selling price of 0.36 $/kWh) that is valid now in Cameroon.

Optimization of Biogas Production by Co-Digestion of Organic Waste (Cow Dung and Water Hyacinth)

The objective of this work is to determine the co-digestion ratio of water hyacinth and cow dung for the optimization of biogas production at Sô Ava, a lake city of Southern Benin. To achieve these ratios, we suppose that the water hyacinth has a high gas yield and cow dung ensures stability in the biodigester because it brings fresh bacteria and has a strong buffering capacity (maintenance of a stable pH). For 45 days, we have introduced a mixture of water hyacinth and cow dung in 5 mini-biodigesters of 10 liters each: digester no1 (100% of cow dung); digester no2 (100% of the water hyacinth); digester n° 3 (50% of the water hyacinth and 50% of the cow dung); digester no4 (75% of cow dung and 25% of water hyacinth); digester no5 (75% of the water hyacinth and 25% of the cow dung). The measurements of the pH, temperature and the proportion of gas (CH4, CO2, O2 and H2S) in the mini-biodigesters was done. The measurements show that the digester n° 5 produces the highest capacity of 15.24L of biogas with 70% of methane while the digester n °2 has the lowest capacity 5.47L of biogas with 58% methane. These results show that the yield of biogas produced is greater when using the mixture of the substrate with the ratio of 75% of water hyacinth and 25% of cow dung. This result encourages the energy recovery from water hyacinth, once considered as a seasonal plague which hinders navigation of local boat in the lake.

Evaluation of the production of biohydrogen during the co-digestion of organic wastes in an upflow hybrid anaerobic reactor

The effect of the hydraulic retention time (24, 12, and 6 h) during the co-digestion of organic residues was studied using a novel upflow hybrid anaerobic sludge reactor with a carbon/nitrogen ratio of 30, initial pH of 5.5, temperature of 35 °C, and a granular inoculum. The reactor performance at the tested HRTs followed the order 650 ± 50 (24 h) > 48 ± 4 (12 h) > 20 ± 2 mL BH2 g-1CDO removed (6 h). The content of the metabolites obtained using an HRT of 24 h followed the order acetic acid > isobutyric acid > butyric acid under acetogenic conditions. However, for HRTs of 12 and 6 h, the sequence was butyric acid > valeric acid > propionic acid > acetic acid. Based on molecular analyses, the biohydrogen selectivity was attributed to the presence of the genera Megasphaera, Clostridium, Lactobacillus, and Prevotella, which accounted for 26%, 2%, 12%, and 29% of the microbial biota at 24 h. Additionally, the yield of the upflow hybrid anaerobic reactor was superior to that of an upflow anaerobic reactor (24 h).

Enhancement of Sewage Sludge Digestion by Co-digestion with Food Waste and Swine Waste

The anaerobic co-digestion of sewage sludge and other organic waste is an attractive method for both waste treatment and biogas production. In this study, we examined the optimal substrate mixing ratio in co-digestion of sewage sludge, swine waste, and food waste using the response surface methodology. The single digestion of sewage sludge produced 138 mL CH4/g total solids (TS) with 35% chemical oxygen demand removal. The co-digestion with food waste and swine waste increased the methane yield to 294 mL/g TS under the optimal mixing ratio of 1:0.39:1 (sewage sludge:food waste:swine waste). The statistical analysis of the experimental data indicated a synergistic effect in the mixing of food waste and swine waste. This study showed that co-digestion of the organic wastes would be a feasible and economic approach to retrofit conventional anaerobic digesters.

Evaluation of Biogas Production from the Co-Digestion of Municipal Food Waste and Wastewater Sludge at Refugee Camps Using an Automated Methane Potential Test System

The potential benefits of the application of a circular economy—converting biomass at Za’atari Syrian refugee camps into energy—was investigated in this study. Representative organic waste and sludge samples were collected from the camp, mixed in different ratios, and analyzed in triplicate for potential biogas yield. Numerous calorific tests were also carried out. The tangential benefit of the co-digestion that was noticed was that it lowered the value of the total solid content in the mixture to the recommended values for wet digestion without the need for freshwater. To test the potential methane production, the automated methane potential test system (AMPTS) and the graduated tubes in the temperature-controlled climate room GB21 were utilized. Also, calorific values were determined for the organic waste and sludge on both a dry and a wet basis. The maximum biogas production from 100% organic waste and 100% sludge using AMPTS was 153 m3 ton−1 and 5.6 m3 ton−1, respectively. Methane yield reached its maximum at a Vs sub/Vs inoculum range of 0.25–0.3. In contrast, the methane yield decreased when the Vs sub/Vs inoculum exceeded 0.46. The optimum ratio of mixing of municipal food waste to sludge must be carefully selected to satisfy the demands of an energy production pilot plant and avoid the environmental issues associated with the sludge amount at wastewater treatment plants (WWTPs). A possible ratio to start with is 60–80% organic waste, which can produce 21–65 m3· biogas ton−1 fresh matter (FM). The co-digestion of organic waste and sludge can generate 38 Nm3/day of methane, which, in theory, can generate about 4 MW in remote refugee camps.

Bioelectricity from Anaerobic Co-Digestion of Organic Solid Wastes and Sewage Sludge Using Microbial Fuel Cells (MFCs)

Recently microbial fuel cells (MFCs) have been considered as an alternative power generation technique by utilizing organic wastes. In this study, an experiment was carried out to generate bioelectricity from co-digestion of organic waste (kitchen waste) and sewage sludge as a waste management option using microbial fuel cell (MFC) in anaerobic process. A total of five samples with different sludge-waste ratio were used with zinc (Zn) and cupper (Cu) as cell electrodes for the test. The trends of voltage generation were different for each sample in cells such as 350 mV, 263 mV, 416 mV maximum voltage were measured from sample I, II and III respectively. It was observed that the MFC with sewage sludge showed the higher values (around 960 mV) of voltages with time whereas 918 mV obtained with organic waste. Precisely comparing cases with varying the organic waste and sewage sludge ratio helps to find the best bioelectricity generation option. Using MFCs can be appeared as the solution of electricity scarcity along the world as an efficient and eco-friendly manner as well as organic solid waste and sewage sludge management.

Addressing operational side effects of co-digestion of organic waste

Addressing operational side effects of co-digestion of organic waste

Nutrient recycles and other side effects of co-digestion of organic waste

Nutrient recycles and other side effects of co-digestion of organic waste

Feasibility study of waste (d) potential: co-digestion of organic wastes, synergistic effect and kinetics of biogas production

The present study investigated the synergistic effect of co-digesting food and green waste from institute campus for enhanced biogas production in different ratios in batch tests (37 ± 1 °C, 90 rpm, 45 days). The results showed that blending improved the biogas production significantly, with highest biogas yield (660 ± 24 mL g−1 volatile solids) that was achieved at 75:25 of food and green waste ratio on volatile solids basis. The yield was 1.7- and 1.9-fold higher than the mono-digestion of food and green waste (370 ± 34; 342 ± 36 mL g−1 volatile solids), respectively. The increase in biogas production may be attributed to optimum carbon to nitrogen ratio resulting in higher yield. The addition of TiO2 nanoparticles showed virtually no effect on biogas production. Characterization was carried out to gain an insight of feedstocks. Modified Gompertz and logistics models were applied for kinetic study of biogas production where modified Gompertz model showed goodness of fit (R 2 = 0.9978) with the experimental results.

Overcoming barriers to codigestion

Codigestion of organic waste with municipal wastewater sludge is growing rapidly. It has many benefits, including diversion of organic waste from landfills, increased renewable energy from biogas production, and potential for revenue from tipping fees. However, there are still barriers to greater widespread application of codigestion. Economics, need for collaboration between utilities, impacts on wastewater application, unsupportive regulations and risks to core wastewater treatment business are obstacles that slow wider adoption of codigestion throughout the world. The research presented analyzes the economic impacts of codigestion, predicts the additional biogas production, and determines the allowable organic loading rate and fats oils and grease (FOG) addition for stable digestion operation. The economic impacts were analyzed on a life cycle cost basis and presented in terms of required tipping fees for different organic wastes, electric rates and residuals handling costs. Standard biochemical methane potential tests were conducted to estimate biogas production from various organic wastes. The specific energy loading rate (SELR) was used to express the allowable organic loading rate. Results from the economic analysis showed that codigestion using existing digesters at a municipal water reclamation facility is more economical than building new digesters. Codigestion was more economical at facilities with high electricity costs and low cost of residuals. Tipping fees for receiving organic waste would be required to offset the net cost of codigestion for wastes other than FOG. There was a net positive economic benefit of receiving FOG without a tipping fee. The upper limit of FOG for stable digestion was found to be 60 percent of the feed by chemical oxygen demand (COD). Stable digestion can be achieved with an SELR of less than 0.25 kgCOD/day/kgVS. The SELR accounts for the strength or energy content of the organic feed measured in COD. It was observed and accounted for by the SELR that anaerobic digesters loaded at higher solids concentrations (resulting in greater inventory of microorganisms in the digesters) can be fed at higher loading rates. Insights into the economics of codigestion and allowable organic loading rates for high strength organic wastes help to overcome some of the barriers to widespread application of codigestion.

Comment on “Synergistic co-digestion of solid-organic-waste and municipal-sewage-sludge: 1 plus 1 equals more than 2 in terms of biogas production and solids reduction” [Water Research 87, 416–423

Co-digestion of organic waste and sewage sludge enhances biogas production and reduces the mass of remaining solids. This phenomenon of enhanced organic matter decomposition by adding labile substrate is known from other habitats like soils and sediments where it is called priming effect. It is thus suggested to adopt the term priming effect also in environmental biotechnology, and in particular for biomethanisation of wastewater sludges by the addition of energy-rich co-substrates.

Biogas Production from Poultry Manure and Cheese Whey Wastewater under Mesophilic Conditions in Batch Reactor

Co-digestion of organic waste is a technology always more frequently applied for simultaneous treatments of several solid and liquid organic wastes. In a co-digestion process the content of nutrients, as well as the negative effects of toxic compounds, can be balanced, increasing the gas yield.Moreover, co-digestion may contribute to a more efficient use of anaerobic digestion (AD) reactors and cost-sharing by processing multiple waste streams in a single facility.The aim of this study is to investigate the biogas production from mixture of Poultry Manure (PM) and Cheese Whey Wastewater (CWW). Batch experiments were performed under mesophilic conditions (37oC) at a pH from 6,5 to 7,5. The methanogenic reactor was operated at hydraulic retention time (HRT) 35 d.The trend of volatile solids (VS) have been verified.

A review on vermicomposting of organic wastes

Generation of the huge amount of solid waste around the globe is a major ecological and technical problem. Vermicomposting may be the viable option to handle solid waste in an environmentally friendly way. This review provides a general overview of viability of vermicomposting processes as an ecofriendly approach. The integrated approach of composting and vermicomposting processes provides better results. Further, to optimize the process of vermicomposting, codigestion of organic wastes provides better opportunity for both microorganisms and earthworms to convert the organic fraction of solid waste under controlled environmental conditions. Feeding, stocking density, pH, C/N ratio, temperature, and moisture, by inference, seem to be the critical factors that influence the vermicomposting process. Furthermore, the end product of vermicomposting, the nutrient‐rich compost, could be used for biogas production. Hence, the management of solid waste and energy production can be achieved at the same time with no further costs. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1050–1062, 2015

Co-Digestion of Organic Waste Products with Wastewater Solids: Final Report with Economic Model

This project furthers the understanding of co-digestion of organic waste with wastewater solids, quantifies the benefits of co-digestion, and provides answers to key questions to help overcome barriers associated with greater implementation of co-digestion programs at municipal WRRFs. The practice of adding waste organic feedstock directly to anaerobic digesters is becoming an attractive way for utilities to generate revenue from tipping fees while boosting biogas production. However, the practice is only used by about 20% of WRRFs with AD due to the uncertainty on how to proceed without causing digester upset. Through lab, pilot-scale, and a study of a full-scale facility, this research addresses some of these operational issues. Includes an Excel-based Economic Model that utilities can use to determine an appropriate tipping fee for handling this waste in the digesters – often the source of additional revenue which makes these energy recovery project viable. This title belongs to WERF Research Report Series . ISBN: 9781780405384 (eBook)

Anaerobic Co-Digestion of Biodegradable Municipal Solid Waste with Human Excreta for Biogas Production: A Review

Biogas, which is principally composed of methane and carbon dioxide, can be obtained by anaerobic fermentation of biomass like: manure, sewage sludge, municipal solid waste. Biogas production represents a very promising way to overcome the problem of waste treatment. Furthermore, the solid residuals of fermentation might be reused as fertilizers. This review clearly indicates that co-digestion of organic waste is one of the most effective biological processes to treat a wide variety of solid organic waste products and sludge as well as biogas production. The prime advantages of this technology include (i) organic wastes with a low nutrient content can be degraded by co-digesting with different substrates in the anaerobic bioreactors, and (ii) the process simultaneously leads to low cost production of biogas, which could be vital for meeting future energy-needs.

Biogas production from anaerobic co-digestion of agroindustrial wastewaters under mesophilic conditions in a two-stage process

Abstract Co-digestion of organic wastes is a technology that is increasingly being applied for simultaneous treatment of several solid and liquid organic wastes, in which the content of nutrients can thereby be balanced, and the negative effect of toxic compounds on the digestion process may be decreased giving an increased gas yield from the biomass. Moreover, co-digestion may contribute to a more efficient use of anaerobic digestion (AD) reactors and cost-sharing by processing multiple waste streams in a single facility. In this study, efficient biodegradation of a mixture containing olive mill wastewater (OMW), liquid cow manure (LCM) and cheese whey (CW) using a two-stage anaerobic process was examined. Two continuously stirred tank reactors (CSTRs) were used under mesophilic conditions (35°C) in order to enhance acidogenesis and methanogenesis. The overall process was designed with a hydraulic retention time (HRT) of 19 days. The acidogenic reactor was initially fed with an influent mixture composed of 55% OMW, 40% CW and 5% LCM. After the 87th day of operation, the mixture was changed to 90% of CW and 10% of LCM based on the actual availability of wastes produced by the respective agroindustries. The average removal of dissolved chemical oxygen demand (COD) was 75.5% and 85.2% for the two examined scenarios at OLR of 5.5 ± 0.36 and 4.5 ± 0.30 g total COD/Lreactor/d, while the methane production rate at the steady state reached 1.35 ± 0.11 and 1.33 ± 0.15 L CH 4 /Lreactor/day respectively.