Prospect of kitchen wastes for biomaterials and biogas production in a biorefinery approach

The production of food wastes is a serious issue in developed and developing countries. The biogas production technology is one of the most sustainable methods for treating food wastes. Currently, there is a great need to implement suitable methods to enhance biodegradation and methane production. This study investigated the effect of manure addition and leachate lime-pretreatment on the biogas and methane production from spoilable municipal solid wastes using a hybrid anaerobic-aerobic bioreactor as a new method. Three laboratory-scale columns were constructed to simulate a hybrid anaerobic-aerobic bioreactor without manure addition and leachate pretreatment as control (R1), two hybrid bioreactors with manure addition and without recycled leachate pretreatment (R2), and manure addition and lime pretreatment of recycled leachate (R3). All simulated bioreactors operated as continuous for about 8 months. Biogas and CH4 production were measured to evaluate the biodegradability of food wastes and efficacy of bioreactors. The results indicated consistently more biogas production under manure addition and leachate pretreatment (R3). The accumulative methane yield was determined to be 17.46, 53.79, and 283.41 mL/gVS for R1, R2, and R3 bioreactors, respectively, after 8 month of operation. The cumulative methane yield in the R3 bioreactor was 16.23 and 5.27 times higher than in R1 and R2 bioreactors, respectively. Therefore, the food waste biodegradation in R3 was greater than in R1 and R2. These results showed that the manure addition and leachate lime-pretreatment were effective in increasing the biogas and methane production of food wastes.

Anaerobic mono and co-digestion of agro-industrial waste and municipal sewage sludge: Biogas production potential, kinetic modelling, and digestate characteristics

Anaerobic digestion (AD) is the biological waste treatment method for the organic fraction of municipal solid waste (OFMSW). AD is notable for its ability to reduce volume and produce biogas from waste. However, the conventional AD of OFMSW has a low degradation rate. In recent years, some treatment method has been used to promote the biogas and methane production of AD. One of these methods is hydrothermal carbonization (HTC). This study aimed to evaluate the effect of hydrothermal carbonization (HTC) temperature and hydrochar: OFMSW ratio as factors on biogas production, methane production, and methane content of anaerobic digestion (AD) as responses was investigated. This study determined the biomethane potential of raw and pretreated OFMSW (hydrochars) in 118 ml serum glass bottles. Based on the Hansen method, all tests were conducted at mesophilic temperature (37 ± 1 °C) in an incubator for 45 days. The response surface method and central composite model were used for designing experimental conditions. Quadratic models were used to estimate the correlation between factors and responses. Also, the optimal conditions for maximizing responses were determined. Biogas production of mixing hydrochar and OFMSW was 41% more than control groups which contained OFMSW and inoculum. The optimal operating conditions to maximize all responses were applied in HTC temperature and hydrochar: OFMSW ratio of 179.366 °C and 2.406, respectively. In this condition, the maximum biogas production, methane production, and methane content were 394 mL/g VS, 284.351 mL/g VS, and 73.176%, respectively. As an OFMSW HTC pretreatment for AD, hydrochar additive has a significantly positive and negative effect on biogas production, methane production, and methane content of biogas depending on operating conditions. Therefore. It is necessary to consider the individual and interaction effects of the temperature and hydrochar: OFMSW ratio, obtain the optimal conditions and determine responses.

Enhancing anaerobic digestion of food waste for biogas production: Impact of graphene nanoparticles and multiwalled nanotubes on direct interspecies electron transfer mechanism

The potential of various biomasses for the production of green chemicals is currently one of the key topics in the field of the circular economy. Volatile fatty acids (VFAs) are intermediates in the methane formation pathway of anaerobic digestion and they can be produced in similar reactors as biogas to increase the productivity of a digestion plant, as VFAs have more varying end uses compared to biogas and methane. In this study, the aim was to assess the biogas and VFA production of food waste (FW) and cow slurry (CS) using the anaerobic biogas plant inoculum treating the corresponding substrates. The biogas and VFA production of both biomasses were studied in identical batch scale laboratory conditions while the process performance was assessed with chemical and microbial analyses. As a result, FW and CS were shown to have different chemical performances and microbial dynamics in both VFA and biogas processes. FW as a substrate showed higher yields in both processes (435 ml CH4/g VSfed and 434 mg VFA/g VSfed) due to its characteristics (pH, organic composition, microbial communities), and thus, the vast volume of CS makes it also a relevant substrate for VFA and biogas production. In this study, VFA profiles were highly dependent on the substrate and inoculum characteristics, while orders Clostridiales and Lactobacillales were connected with high VFA and butyric acid production with FW as a substrate. In conclusion, anaerobic digestion supports the implementation of the waste management hierarchy as it enables the production of renewable green chemicals from both urban and rural waste materials.

The objective of this research was to analyze the potential of biogas production with co-digestion between food waste and cow dung. The experiment research was batched with small scale and scale up with semi-continuous, temperature was operated within 35 - 37 °C. The suitable condition for biogas production between food waste and cow dung was presented with 75:25 (T1). 55 mL of the biogas potential was obtained which is considered as small scale. Thus, the scale up was presented in 75:25 (T1) ratio. In term of scale up the biogas obtained from the production is 650 ml which is higher than small scale. The scale up reactor of biogas production was 100 liters. Chemical oxygen demand (COD) was reduced from 30,000 to 5,000 - 7,000 mL L-1. The efficiency of COD was obtained 76.67 - 83.3 %, respectively. In term of total solid, it was decreased from 19,000 to 16,500 mL L-1. Initial VFA was presented 4,000 mL L-1, and final was presented 3,800 mL L-1, respectively. However, the biogas production from food waste and cow dung can enhance the performance of municipal solid waste and alternative energy production. Finally, the finding of co-digestion in biogas production system suggested utilization in household and communities.
 HIGHLIGHTS
 
 Food waste is the major waste in household, and it has high potential for energy production
 Co-digestion in biogas production system that suggested utilization in household and communities
 The biogas production from food waste and cow dung can enhance the performance of municipal solid waste and alternative energy production
 
 GRAPHICAL ABSTRACT

The effect of thermochemical pre-treatment on biogas production efficiency from kitchen waste using a novel lab scale digester

This study investigated the use of anaerobic biodigestion as an ecological technique for treating organic waste in urban solid waste. Biogas production is carried out through the action of microorganisms, and the use of enzymatic hydrolysis can increase biogas production, although it presents economic challenges. The aim of the study was to pre-select microbiological groups and enzymes to optimize the process and increase biogas production using statistical tools. Organic waste from a restaurant and sludge from a sewage treatment plant in Brazil were used, and three bacterial strains and 12 groups of microorganisms, as well as commercial enzymes, were evaluated. The study was divided into four stages to reduce the number of independent variables and increase the accuracy of methane and biogas production results. The results indicated that careful selection of microbial groups had a significant positive impact on biogas and methane production. The interaction between pre-selected groups of microorganisms and enzymes resulted in significant positive effects on cumulative biogas and biometane production. The study concluded that careful selection of microbial groups is essential to maximize biogas production and the efficiency of the anaerobic digestion process. Further, a more detailed identification of microorganisms and their interactions is needed to further optimize biogas production. In general, the appropriate choice of microbial groups is fundamental to the success of anaerobic digestion and biogas production.

The present article examines the overall use of renewable energy among the European leaders and Poland’s place in such statistics. It also shows the potential in use of the so–called: “green energy” and its positive influence on the local and global ecosystem. The article shows how important it is to abandon the use of fossil energy sources are creating a negative ecosystem during the extraction and their use. According to the author, the production and use of biogas fuel is an alternative. The production of biogas is not only related to energy production, but it also improves the situation of materials management of green waste, waste from agriculture and plants treatment waste which are widely underrated. The use of these wastes in biogas production allows not only the neutralization of their impact on the environment but it also creates great opportunities in the heat and electricity production.
 Further, the article features numerous tables and graphs that show the great potential in the production and utilization of biogas as an alternative fuel in Poland and other countries with similar resource–energy potential. Another goal of this article is to debunk the theory that the process of methane fermentation in agricultural biogas plants produces odour which in fact is due to using outdated technology. The conclusions clearly indicate the usability of this type of investment and simultaneously reinforce the belief that the proper environmental policy of the state and local governments –understood as an eco–friendly regulation– gives a chance for a clean environment and economic growth potential.

The effects of thermal (autoclave and microwave irradiation (MW)) and thermo-chemical (autoclave and microwave irradiation – assisted NaOH 5N) pretreatments on the chemical oxygen demand (COD) solubilisation, biogas and methane production of anaerobic digestion kitchen waste (KW) were investigated in this study. The modified Gompertz equation was fitted to accurately assess and compare the biogas and methane production from KW under the different pretreatment conditions and to attain representative simulations and predictions. In present study, COD solubilisation was demonstrated as an effective effect of pretreatment. Thermo-chemical pretreatments could improve biogas and methane production yields from KW. A comprehensive evaluation indicated that the thermo-chemical pretreatments (microwave irradiation and autoclave- assisted NaOH 5N, respectively) provided the best conditions to increase biogas and methane production from KW. The most effective enhancement of biogas and methane production (68.37 and 36.92 l, respectively) was observed from MW pretreated KW along with NaOH 5N, with the shortest lag phase of 1.79 day, the max. rate of 2.38 l·day<sup>–1</sup> and ultimate biogas production of 69.8 l as the modified Gompertz equation predicted.

Anaerobic co-digestion (AcoD) of fish sludge (FS) with food waste (FW), and fruit and vegetable waste (FVW) for biogas and methane production was optimised in small-scale bioreactors, and batch and semi-continuous pilot-scale digesters, under mesophilic (37 ℃) conditions. An experimental mixture design was first applied to small-scale biomethane potential (BMP) tests, to determine the optimal mixture proportions of the AcoD of FS, FW, and FVW that maximise the specific methane yield (SMY in NmLCH4 gVS−1). The optimal mixture proportion was 67%FS:18%FW:19%FVW (w/w), producing 401 mLCH4 gVS−1, which was 8 times higher than the SMY when FS was mono-digested (48 mLCH4 gVS−1). The SMY achieved in batch pilot-scale digesters were 70–82% of methane yields obtained in BMP tests under the same operating conditions, with stable biogas production and no apparent inhibition during the batch run. Semi-continuous operation of the pilot-scale digester was undertaken with organic loading rates (OLRs) of 1, 2, and 3 gVSL-1d-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$gVS{L}^{-1}{d}^{-1}$$\\end{document}, provided intermittently. However, the digester did not achieve stable biogas production at all of the evaluated OLRs, due to the intermittent feeding and accumulation of volatile fatty acids (VFAs): Improved process stability was achieved at an OLR of 2 gVSL-1d-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$gVS{L}^{-1}{d}^{-1}$$\\end{document}, compared to OLRs of 1 and 3 gVSL-1d-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$gVS{L}^{-1}{d}^{-1}$$\\end{document}. Optimisation of the AcoD process resulted in attractive biomethane yields from FS with FW and FVW co-feeds, indicating that producing biogas from co-digestion of FS with relevant substrates is a valuable managing tool for FS, while simultaneously providing renewable energy. The work provides novel data that elucidated optimal proportions in which to combine FS, FW and FVW to obtain optimal biogas production, and provided important new information relevant for the scale up and continuous operation of an AD process for treating FS.Graphical

Food waste has become a challenging global issue due to its inefficient management, particularly in low and middle-income countries. Among food waste items, fruit peel waste (FPW) is generated in enormous quantities, especially from juice vendors, resulting in arduous tasks for waste management personnel and authorities. However, considering the nutrient and digestible content of organic wastes, in this study four types of FPW (pineapple: PA; sweet lemon: SL; kinnow: KN; and pomegranate: PG) were investigated for their potential use within biogas production, using conventional and electro-assisted anaerobic reactors (CAR and EAR). In addition, the FPW digestate obtained after the biogas production experiments was considered as a soil bio-fertilizer under radish (Raphanussativus L. cv. Pusa Himani) cultivation. In the results, all four types of FPW had digestible organic fractions, as revealed from physicochemical and proximate analysis. However, PA-based FPW yielded the maximum biogas (1422.76 ± 3.10 mL/62.21 ± 0.13% CH4) using the EAR system, compared to all other FPW. Overall, the decreasing order of biogas yield obtained from FPW was observed as PA > PG > SL > KN. The kinetic analysis of the biogas production process showed that the modified Gompertz model best fitted in terms of coefficient of determination (R2 > 0.99) to predict cumulative biogas production (y), lag phase (λ), and specific biogas production rate (µm). Moreover, fertilizer application of spent FPW digestate obtained after biogas production significantly improved the arable soil properties (p < 0.05). Further, KN-based FPW digestate mixing showed maximum improvement in radish plant height (36.50 ± 0.82 cm), plant spread (70.80 ± 3.79 cm2), number of leaves (16.12 ± 0.05), fresh weight of leaves (158.08 ± 2.85 g/plant), fruit yield (140.10 ± 2.13 g/plant), and fruit length (25.05 ± 0.15 cm). Thus, this study suggests an efficient method of FPW management through biogas and crop production.

Dilute alkali pretreatment of softwood pine: A biorefinery approach

BACKGROUNDCoffee husks (CH) are an abundant lignocellulosic residue that can be converted into biofuels and bioproducts through sustainable and economical processes in a biorefinery approach. For that, steam explosion (SE) pretreatment stands out as a technique to overcome its recalcitrant nature and enable byproduct valorization. In this study, solid and liquid fractions were separated after pretreatment for saccharification and biogas production, respectively. The research relevance relies on the contribution to environment decarbonization and monetization of decarbonization credits (CBIO) generated from the production of renewable fuel from waste biomass under different operational conditions (with and without pretreatment).RESULTSLiquid hydrolysate generated by SE condition at 210 °C and 15 min led to the highest biomethane production (292 NmL CH4 g CODfed−1). Similarly, high‐severity pretreatment also favored the enzymatic hydrolysis yield of the solid fraction (49%). In terms of environment decarbonization, SE promoted not only a lower carbon intensity when compared to the process without any pretreatment (3.8 vs. 6.4 g CO2eq MJ−1), but also increased the monetization of decarbonization credits by 175%, which represented a potential revenue of US $1 481 330.CONCLUSIONHigh temperatures of SE pretreatment of CH at 210 °C were able to promote biogas production and fermentable sugars. In addition, the process reduced carbon emissions and increased the revenue from CBIO commercialization. Therefore, SE proved to be a sustainable and economic alternative for consideration in new green businesses from lignocellulosic residues such as CH. © 2021 Society of Chemical Industry (SCI).

Biogas production is a process with great potential. It uses the biodegradable raw materials of animal, vegetable and municipal waste. The amount of municipal as well as agricultural waste is increasing every year. This waste is an unmanaged and nuisance waste, and using it in biogas plants reduces the amount of waste. Biogas production is part of the EU’s policy to reduce dependence on fossil fuels and use energy from renewable sources (diversification of energy sources). Its importance is certain to increase in the future as energy demand increases. This article deals with the economical use of biodegradable waste for biogas production in Poland and Germany. Both countries have a similar agricultural and municipal waste structure. An agricultural biogas plant is one way of obtaining energy based on renewable energy sources (RES). Energy production from agricultural biogas will allow Poland to meet the 32% obligation imposed by the EU and Germany to continue to be the market leader in biogas plants. The biogas market in Poland is growing, while in Germany, there is a decline in biogas installations. The article indicates what changes need to take place in agriculture and the use of municipal waste in these countries to sustain the development of biogas plants. Both countries should maintain animal husbandry to ensure continuous access to substrate and use waste for production rather than growing maize or other mixtures only for biogas plants. Due to the high price of chemical fertilisers, pulp from biogas plants should be an alternative to chemical fertilisers in both countries, which will contribute to greener crops. The governments of both countries should support such measures.