Anaerobic co-digestion of food waste for energy production - a review

Anaerobic digestion is a recognised methodology for stabilising any kind of wastewater as well as degradation of organic matter. A useful end-product of anaerobic digestion process is bio-gas. Bio-gas is fuel gas, which is a mixture consisting of methane having concentration of about 65% and carbon dioxide having concentration of about 35%. In order to increase the yield of anaerobic digestion one of the options is carrying co-digestion with several substrates. When co-substrate is used along with anaerobic decomposition process it results in positive synergism between digestions medium improves yield of biogas. Solid waste management currently focuses only on disposal options instead of harnessing or recovering energy. Therefore, by moving energy-rich food waste from landfill sites to anaerobic treatment, it can help the society to manage solid waste in a sustainable manner and also generate renewable energy. Anaerobic co-digestion as a treatment option for solid waste is discussed here. Attention is laid towards anaerobic digestion using various substrates like municipal solid waste, domestic sludge, industrial sludge, animal waste, crop residues, weeds, etc.

Enhancement of biogas production in anaerobic co-digestion of food waste and waste activated sludge by biological co-pretreatment

Determinants of municipal solid and hazardous waste management in the occupied Palestinian territory: a cross-sectional study

Solid-state anaerobic co-digestion of food waste and cardboard in a pilot-scale auto-fed continuous stirred tank reactor system

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

Biogas generation from food waste through anaerobic digestion technology with emphasis on enhancing circular economy in Sub-Saharan Africa – A review

Anaerobic co-digestion of food waste and agricultural residues: An overview of feedstock properties and the impact of biochar addition

Anaerobic digestion (AD) is one of the significant strategy for the management of solid organic waste. It is a biological process that degrade the organic matter in the absence of oxygen with ultimate products being CO2 and CH4. Solid waste has to be treated, mechanically or chemically or biologically prior to fed into the anaerobic digesters for an efficient treatment. Solid wastes with lignocellulosic and hemi cellulosic materials are difficult to degrade and need proper pre-treatment. The anaerobic digester should follow optimum parameters such as; temperature 37 °C for mesophilic and 55 °C for thermophilic digestion, pH 6.5–8.0, hydraulic retention time (HRT) of about 35–40 days for mesophilic and 15 days for thermophilic digestion, feed C/N ratio 30/1 for a successful degradation of waste material and biogas production. A balanced active bacterial and methanogenic Archaeal population in the AD is most important factor that influence the stable digestion of the waste material. Molecular techniques based on 16S rDNA gene and other functional gene markers such as McrA, Pct, nif are handy to monitor the treatment process. The most advanced next generation DNA sequencing platforms have been serving to identify the community structure and playing an important role in assigning the microbial communities involved to their function. These techniques further helps in rapid bioaugmentaion of AD for the stable operation of digestion process.

Potential use of the organic fraction of municipal solid waste in anaerobic co-digestion with wastewater in submerged anaerobic membrane technology

India generated around 1.45 lakh tonne of municipal solid waste (MSW) per day, out of which 40% is organic biodegradable waste, which has food waste as the major component. Scientific conversion of this food waste to energy is always challenging. In the present study, anaerobic digestibility of food waste as a mono digestion substrate and co-digestion of food waste with water hyacinth were tested and analyzed in a batch type anaerobic digester of capacity 60 l. Four different samples, i.e., only food waste, only water hyacinth, and with food waste to water hyacinth in the ratio of 15:2 and 8:3 to maintain total solids contain equal in all samples were analyzed for the anaerobic digestion (AD). Biogas yield for the above four samples were found to be 370.85 (ml/g VS), 320.54 (ml/g VS), 286.50 (ml/g VS), and 298.83 (ml/g VS), respectively. The average methane content was found to be 68.3%, 58.2%, 52.1%, and 65.4%, respectively whereas CO2 content was found to be 30.2%, 40.9%, 46.6%, and 33.3%, respectively, using gas chromatography. The temperature variation for anaerobic digester was measured in the range of 32 to 43 °C during the experiment without supplying any external heat. pH value of all samples was ranged between 6.5 and 7.5 at the end of the experiment. The results of this study conclude that co-digestion of food waste with water hyacinth has higher operational stability compared to mono digestion of food waste.

Mixed Solid Municipal Waste-Based Biochar for Soil Fertility and Greenhouse Gas Mitigation

ABSTRACTBiopower can diversify energy supply and improve energy resiliency. Increases in biopower production from sustainable biomass can provide many economic and environmental benefits. For example, increasing biogas production through anaerobic digestion of food waste would increase the use of renewable fuels throughout California and add to its renewables portfolio. Although a biopower project will produce renewable energy, the process of producing bioenergy should harmonize with the goal of protecting public health. Meeting air emission requirements is paramount to the successful implementation of any biopower project. A case study was conducted by collecting field data from a wastewater treatment plant that employs anaerobic codigestion of fats, oils, and grease (FOG), food waste, and wastewater sludge, and also uses an internal combustion (IC) engine to generate biopower using the biogas. This research project generated scientific information on (a) quality and quantity of biogas from anaerobic codigestion of food waste and municipal wastewater sludge, (b) levels of contaminants in raw biogas that may affect beneficial uses of the biogas, (c) removal of the contaminants by the biogas conditioning systems, (d) emissions of NOx, SO2, CO, CO2, and methane, and (e) types and levels of air toxics present in the exhausts of the IC engine fueled by the biogas. The information is valuable to those who consider similar operations (i.e., co-digestion of food waste with municipal wastewater sludge and power generation using the produced biogas) and to support rulemaking decisions with regards to air quality issues for such applications.Implications: Full-scale operation of anaerobic codigestion of food waste with municipal sludge is viable, but it is still new. There is a lack of readily available scientific information on the quality of raw biogas, as well as on potential emissions from power generation using this biogas. This research developed scientific information with regard to quality and quantity of biogas from anaerobic co-digestion of food waste and municipal wastewater sludge, as well as impacts on air quality from biopower generation using this biogas. The need and performance of conditioning/pretreatment systems for biopower generation were also assessed.

Managing food waste is key to tackling climate change

The study sought to assess the social context of solid waste disposal pattern of residents in Ibadan metropolis, in order to assess the Solid waste disposal patterns of people in Ibadan metropolis, Oyo State, Nigeria. Specifically, the study identified solid waste disposal habits of residents, frequency of clearing the dumpsters, accessibility of waste dumpsters to people determines the waste disposal pattern of people; and analyze the willingness of people in Ibadan to pay for improved service. Solid waste management has been part of human activities right from time. Efforts by Oyo State Government is seen in the collection of dirt that have been placed on the medians. Waste generation is an unavoidable product of man activities, however, sustainable management of such waste is a challenge faced in many countries today. Nigeria, a developing country in Africa, has been in a quandary of how to efficiently manage the municipal solid waste its population generates. Many states in the country lack adequate plans and infrastructure required for efficient and sustainable management of municipal solid waste. For Ibadan, the largest city in Nigeria, the problem is further compounded by its rather large and still increasing population. In this research, Ibadan metropolis is taken as a case study; the rate of solid waste handling in households as regards solid waste management from household collection to final disposal are focused upon. The study found out that 45.6% drop their refuse in the dumpsters as 18.8% burns their refuse, 17.7% of the respondents drops their waste on the median, 12% in the drainage while 6% opts to drop their waste in the streams. On the effectiveness of the Private operators collecting waste from the respondents, the study found out that 7.6% effective, 37.5% of the respondents says the operators waste collection is poor, 7% says it is abysmal while 43.5% said it is not applicable to them because they do not have storage containers in their houses and as a result did not subscribe to their service. Many countries, particularly the developed ones, have employed options in the waste management hierarchy for sustainable management of their municipal solid waste and the blend of options employed is usually highly dependent on local factors. Following the waste management hierarchy, possible options for sustainable municipal solid waste management in Ibadan are discussed. It is concluded that waste reduction, reuse, and recycling are potential management options for the state. Landfilling will remain an important option for final disposal but reliance on this method could be significantly reduced if management options are exploited to the maximum in a sustainable solid waste management structure in Ibadan metropolis. Key Words: Waste handling, Ibadan Metropolis, Landfill, Municipal Solid Waste Word Count: 435

1 - A summary of solid waste generation and management strategy