Search

With the rapid increase of the human population and the concomitant increase in freshwater demand, pressure on this natural resource is increasing. One of the approaches used to overcome water scarcity in several parts of the world is desalination of brackish or seawater. Coupling seawater reverse osmosis (SWRO) with renewable energy (RE) is an active research area and understanding the environmental impact of these integrations using Life Cycle Assessment (LCA) is one of the tools available for the selection of sustainable water supply options for remote communities. This study uses LCA to assess the feasibility of integrating a SWRO with a hybrid energy system to meet the water needs in a remote community. The RE is supplied via electricity generated from biogas produced from the anaerobic digestion (AD) of the organic fraction of municipal solid waste. A 4500 m3/day SWRO plant was designed using WAVE software to satisfy the water demand of a small/medium town in a remote area in Lebanon. The biogas plant sizing was performed using HOMER Pro and different renewable percentages were tested. Biogas characteristics were taken from an existing organic waste AD plant in Lebanon. Based on the available mass of solid waste, the maximum achievable renewable fraction required to operate the SWRO was found to be 60%; the remaining electrical demand was supplied from the grid. The LCA was performed using Simapro Ph.D. version 9 to quantify the environmental impacts of this integration. IMPACT2002+ impact assessment method was used. Results show that using AD to power desalination is viable from an environmental perspective and achieves significant reductions in many categories when compared to conventional fossil fuels. Furthermore, increasing the renewable fraction in the hybrid energy system results in further reduction in the environmental impact. In particular, a 60% reduction in global warming potential was observed compared to conventional fossil fuels. However, for some categories, the impact increases upon increasing renewable fraction particularly for categories related to toxicity, eutrophication and acidification and this is mainly attributed to digestate application on land, highlighting the need for digestate enhancement. Accordingly, the system can be further improved by increasing the amount of waste collected and transformed and adopting a more site-specific design.

Returning crop straw to the field not only improves the nitrogen (N) supplying capacity and N retention of soil but also decreases the amount of rural organic waste and prevents air pollution. Therefore, understanding the mechanisms of the N release and re-adsorption dynamics on crop straw residue during straw decomposition in agricultural soil is important, and this understanding can help us strengthen N fertilizer management during the crop growth period. An on-farm incubation experiment was conducted in the Jianghan Plain in Central China under flooded conditions using the nylon mesh bag method. Results showed that the decomposition rate of crop straw was much faster at the beginning of the incubation stage, whereas it was steady during the later stage with no observed differences among the three types of crop straw. After 120 d of incubation, the cumulative decomposition proportion of rice straw, wheat straw and rape straw was 72.9, 56.2, and 66.9%, respectively. The proportion of N that released from the three crop straws was 52.0, 54.4 and 54.9%, respectively. The zeta potentials and Brunauer, Emmett and Teller (BET) surface area of the rice, wheat and rape straw residues increased gradually as the decomposition period progressed. The water adsorption capacity of the rice straw was significantly affected during the decomposition period. The saturated water adsorption capacity of rice straw was the highest at 30 d of decomposition (4.17 g g–1) and then decreased slightly. The saturated water adsorption of wheat and rape straws reached the lowest value at 30 d and then gradually increased and became stable. All the results demonstrated that crop straw and straw residue can re-adsorb NH4+ ions from the surrounding solution. The re-adsorption was affected by the decomposition period and concentration of exogenous NH4+ and was independent of the crop species via the combined efforts of physical and chemical adsorption, ion exchange and water retention on residue surfaces. Future studies will focus on straw returning and N fertilizer application at different levels of moisture content of the soil reduce potential negative effects such as water-logging and excess N caused by the straw substrate.

In this study, an alternative method is proposed for producing electricity using microbial fuel cells (MFCs) and fruit waste in case of industries and farmers. Herein, MFCs were manufactured using zinc and copper electrodes and three types of organic waste (R. ulmifolius, H. undatus, and M. citrifolia) as the substrate. The results revealed that the H. undatus waste generated the highest voltage and current values, i.e., 1.17 ± 0.12 V and 25.78 ± 0.89 mA, respectively, in an open circuit. However, all the substrates exhibited acidic pH values. The H. undatus substrate reported the highest voltage, power density (PD), and current density (CD) values at a V max value of 1.11 ± 0.25 V, a PD max value of 0.0719 ± 0.0012 W/cm2, and a CD max value of 0.051 A/cm2. Conversely, the R. ulmifolius substrate exhibited the lowest values at a V max value of 0.96 ± 0.13 V, a PD max value of 0.0668 ± 0.0013 W/cm2, and a CD max value of 0.025 A/cm2. The micrographs denote that the Cu anode porosity of H. undatus is higher when compared with those of the remaining two substrates, and the Pichia guilliermondii, Candida boidinii, and Brevibacillus laterosporus microorganisms were observed in its anodic biofilm.

Biogas stands out as an alternative to traditional sources of energy since it presents a high methane content, and it is mainly produced by anaerobic digestions of organic wastes. Typical biogas streams do not only consist of biomethane but also carbon dioxide, water, ammonia, hydrogen sulfide or siloxanes, depending on the source of the organic waste. Therefore, it is important to remove all these contaminants to obtain a high-quality stream in a process known as biogas upgrading. Currently, there is not a predominant technology, all of them presenting advantages and drawbacks to be solved. In this work, we test a biogas upgrading process based on CO2 chemical absorption by ionic liquids (ILs). The complete process was evaluated involving absorber and stripping columns in a wide range of operating temperatures and pressures to reach biomethane of 97% purity from an industrial biogas stream. Best specific energy consumptions are found at 50 °C in the absorber and 95 °C in the stripper at atmospheric pressure. Increasing the operating pressure of the absorber to 6 bar reduces the energy consumption from 0.8 kWh/Nm3 to 0.2 kWh/Nm3. This is mainly because of the reduction in IL flow (almost a half) and that the thermal energy needed is provided by the exothermic reaction and no external requirements are needed. IL-based proposal for biogas upgrading was found able to efficiently retain CO2 but also other main impurities (H2S, H2O, siloxanes) producing biomethane with quality standards. Results from IL-based process reveal savings in operating cost and nearly the same equipment investment costs than available technologies (PSA, water and amine scrubbing, and membranes) for biogas upgrading process, The authors are very grateful to Ministerio de Ciencia e Innovación (MINECO) of Spain (PID2020-118259RB-I00) and Comunidad de Madrid (P2018/EMT4348) for financial support. We also thank Centro de Computación Científica de la Universidad Autonóma de Madrid for computational facilities

A large quantity of leachate is generated during municipal solid waste collection operation and in landfills due to the large amount of organic waste and high humidity. The content of medium chain fatty acids (MCFAs) in the leachate is a low cost feedstock for bio-based chemical and fuel production processes. The aim of this study is to investigate the MCFA production potential of three leachate ages through chain elongation process under uncontrolled pH batch test. Moreover, the effect of using different external electron donors (ethanol, methanol and a mixture of both) is studied. The experiment consists of characterizing the samples then adding external electron donors with a specific ratio to leachate samples under mesophilic temperature. For this investigation, also a statistical analysis is done, which shows the production of MCFAs is highly influenced by leachate age. The results indicate that the production of even-numbered acids increase from 600 to 1,000 mg/L by the end of the ethanol chain elongation experiment for young leachate. However, a higher MCFA production of more than 1,000 mg/L is achieved by using the mixture of methanol and ethanol as electron donor. Furthermore, all methanol chain elongation experiments lead to an odd-numbered production of MCFAs, such as pentanoic and heptanoic acids. These results confirm the potential improvement of MCFA production from leachate through choosing the optimal leachate age and electron donor. Overall, producing MCFAs from leachate is a good example of circular bio-economy because waste is used to produce biochemicals, which closes the material cycle.

The high moisture content and perishable organic waste of municipal solid waste (MSW) in China have caused the severe odor nuisance to be one of the crucial reasons for resident complaints. Understanding the environmental risks of odorous compounds lays the foundations for resolving the problems. This study collected concentration data of 86 odorous compounds in five types of MSW processing facilities/equipment which can well represent the whole process of MSW stream, including waste bins and transfer stations for collection, compost plants and anaerobic digestion plants for utilization, and landfills for final disposal. The results revealed that the occupational health risks of odorants were not fully consistent with the compound concentrations and olfactory annoyance. Higher odorous compound concentrations and more severe olfactory annoyance can be found in the MSW utilization and disposal facilities, but the occupational carcinogenic risk (2.79 × 10−5–1.12 × 10−3) was non-negligible along the whole MSW stream. Aromatic hydrocarbons and halogenated hydrocarbons were crucial contributors to the carcinogenic risk of odorous compounds emission from these facilities. Particularly for estimating the adverse impact range of MSW facilities, the carcinogenic risk was the most critical factor, implying impact distance of ∼1.5 km for MSW transfer station and ∼5 km for landfill, and even higher for the regions (such as southwest China) with lower wind speed and higher atmospheric stability. In addition to current regulations, another 5 compounds (acetaldehyde, 1,3,5-trimethylbenzene, 1,2-dichloroethane, acrolein, and benzyl chloride) that displayed high carcinogenic risks were suggested to be concerned. This study provided insights for the policymakers regarding MSW odors management, especially underscoring the importance of considering the health risks of odorous compounds.

Globally, the economy and technologies are fundamentally depending upon the available energy resources owing to the renewability, green, and sustainable. Renewable energy from the waste organic biomass is among the most efficient, effective, and economic green alternatives amid the numerous other sources at present accessible. Anaerobic digestion (AD) is amidst the eminent techniques for converting the organic waste into the bio-energy. It requires low capital and per unit energy production cost, in comparison to the other available renewable energy sources viz., solar, wind, and hydro. This chapter covers the potential utilization of different organic wastes using various pretreatment techniques, operating parameters, codigestion, and trends in the process intensification with great emphasis on waste-to-energy. Focused discussion is given to the codigestion, coupling AD with other waste-to-energy conversion technologies, and modeling of anaerobic codigestion process, made available to the digestion process. Also, the role of different government policies and barriers that are playing vital role in AD promotion along with the bottlenecks in its growth are discussed.

For centuries, organic wastes have been used in agricultural operations as soil amendments. Various organic amendments are frequently utilized in agricultural operations because they have been known to improve soil health properties like water holding capacity, nutrient availability, porosity, etc., and biological properties like microbial activity. Compost, when added to the soil as an amendment, has an immediate impact on various physicochemical properties like pH, OC, metal (loid) solubility, etc. Organic waste amendments, when applied to heavy metal contaminated soils not only enhance its fertility properties but also diminish bioavailability and mobility of potentially toxic elements by promoting certain processes like complexation, sorption, etc. The application of these amendments ameliorates the phytoremediation process in contaminated sites. Amendment of soil with compost enhances the growth of plants as well as favors the activity of soil microbiota. These two associates together to strengthen the process of phytoremediation, plant resilience towards stress as well increase the production of plant biomass. It has also been suggested that compost application instigates differential impact on the plants according to their species. The utilization of compost as an organic amendment in various agricultural practices has been reported to enhance soil fertility, crop production, as well as assist in phytoremediation of metal-contaminated sites. However, there is a need to evaluate each organic waste amendment/compost for its effect on metal mobility before its application in fields. More extensive research is needed to increase our understanding of the mechanisms involved in assisted phytoremediation compost application in contaminated sites.

Biohythane, the blending of biohydrogen—biomethane with hydrogen concentration ranging in between 10% and 30% (v/v). It can be generated via utilizing various organic substrates through two-stage sequential anaerobic stages, that is, the dark fermentation step followed by the anaerobic digestion step, for biohydrogen and biomethane production, respectively, for viable biohythane production from waste organics. In comparison to the conventional biogas, biohythane is advantageous owing to its eco-benign, greater bio-energy recovery, and smaller fermentation duration. However, the conversion of organic waste to biohythane is presently at the bench scale and requires the bioprocess study and further scaling up to industrial level are obligatory. Besides, this chapter brought for forefronting the biochemical reactions, thermodynamics involved, production process, various organic waste feedstocks, two-stage sequential anaerobic stages, of biohythane production. Finally, the energy aspects techno-economic, current challenges and future perspectives for further scaling up of the process have been discussed.

Lactic acid is one of the most commonly used organic acids in various industries due to its versatile applications. To meet the market demand its production by various methods, such as chemically and microbiologically, is gaining significant interest. Chemically synthesized lactic acid (hydrolysis of acetonitrile) is generally a racemic mixture of D- and L-lactic acid which further needs purification for use in pharma and food industries. On the other hand, lactic acid produced by microbial fermentation is in an optically pure form of D- or L-lactic acid and does not require any further purification. Microbes used for lactic acid fermentation, such as bacteria, fungi, yeast, and algae, have the potential to use lignocellulosic biomass, organic agrowaste, kitchen waste, dairy, and petroleum industry waste as a feedstock. Therefore recycling of different organic waste for the production of lactic acid not only resolves the issues of waste management but may also help in reducing the production cost of lactic acid. These microorganisms ferment both pentose and hexose sugars to the desired product by two different pathways, i.e., homolactic and heterolactic fermentation pathways. In the course of these pathways, other than lactic acid there are a few other economically important platform chemicals (acetic acid, ethanol, butanol, etc.) also produced. Different microbes play a specific role at different stages of organic waste recycling to lactic acid. Briefly, lignocellulolytic and different glucoamylases-producing microbes (fungi and bacteria) are the main players in the initial steps of pretreatment and saccharification of biomass. After saccharification, when monomeric or dimeric sugar is released from the biomass, the fermentative lactic acid bacteria converts these sugars to the isomeric form of lactic acid. The obtained lactic acid is purified further by various mechanisms and the pure lactic acid then can be used in pharmaceutical, cosmetic, textile, and food industries.

Industrialization and rapid growth of population have led to an increase in the generation of urban wastes. A significant portion of this waste constitutes the organic fraction which could be utilized as a bioresource for recovery of value-added products (biofuels, biochemicals, enzymes, bioplastics, bioelectricity), via bioprocessing technologies such as anaerobic digestion, microbial fermentation and bioelectrochemical systems. Bioprocessing of urban waste is the most reasonable method among the existing diverse methods of waste management in terms of its cost, potential and generation of non-toxic products. This review exclusively covers the strategies adapted for bioprocessing of urban waste. The microbes used during the bioprocessing of these wastes, are known to have a significant potential for degradation of organic waste fractions. In addition, bioprocessing technologies could be combined with other waste treatment methods to enhance the efficacy of waste management. However, these technologies could be successfully implemented only when they receive the support from the national and local governments.

A study was steered to explore the effect of rock mineral addition (i.e., rock phosphate (RP), dolomite (DM) and mica (MC)) in organic wastes (e.g., water hyacinth and paddy straw) along with microbial inoculums on vermicompost quality. Different amalgamations of four microbial inoculums viz., Trichoderma viride, Azotobacter chroococcum, Bacillus polymixa and Bacillus firmus, and three rock minerals i.e., RP, DM, and MC were used during vermicomposting process to access their effect on the quality of mature vermicompost. A significant reduction in pH, organic carbon, C/N ratio, while significant increase in humic acid, total nitrogen, available phosphorus and exchangeable potassium was observed in each of the vermibeds. Furthermore, enzymatic activities were also boosted considerably due to Vermi-stabilization. Application of rock minerals at 10% (200 g in 2 kg organic waste mixture) along with microbial inoculants in the vermicomposting process promoted the availability of macronutrients as compared to control treatment. The results showed that the combination of rock minerals and microorganisms along with earthworms facilitated the decomposition and reduced the overall time required for composting besides producing a nutrient-enriched vermicompost product.

A study on biofertilizer production via oxidation of heterogeneous mass and microbial decomposition of organic matter in the digestate obtained after anaerobic digestion of post biocoagulation sludge was undertaken. The digestate was characterized. Effect of process variables on composting was investigated. The kinetics of composting was studied. The characterization results show that digestate and saw dust contains macro (nitrogen-N, phosphorus-P, magnesium-Mg, sodium-Na, Calcium-Ca and potassium-K) and micro (manganese-Mn, zinc-Zn, Fe-iron and Cu-copper) nutrients that when composted can be used as biofertilizer/soil improver. Also, the final compost (biofertilizer) contains Zn, Cr, Cu, Cd and Pb that lay within the recommended limits for agricultural use. The kinetic data fitted very well to the second order model with R 2 of 0.9675 and activation energy of 1442.15 kJ mol . Composting kinetic analysis showed that temperature dependence of rates reaction clearly followed the Arrhenius equation. Also, the kinetics results revealed that the degradation of organic waste could be quantitatively predicted using the second order reaction model. It can be concluded that the composting of digestate with saw dust resulted in biofertilizer production; thus, converting waste to wealth.

The management of municipal solid wastes represents one of the biggest challenges for the actual implementation of the circular economy. While the main “dry” fractions (such as plastics and paper) can be easily recycled, treatments for both the valorisation of the organic waste and for the disposal of leachate (produced by the landfilling of unsorted municipal waste) often turn out to be inadequate and expensive. Particularly, the leachate management is a critical issue since the mature landfill leachate (MLL) must be treated for decades even after the landfill closure. In this study, an innovative approach is proposed and it consists in an integrated system of active filters and anaerobic reactors for the simultaneous treatment of both waste streams (i.e., organic waste and MLL). Firstly, bio-refractory compounds (e.g., metals) present in MLL are removed by filtration on active materials (i.e., zero valent iron (ZVI) and granular activated carbon (GAC) or ZVI and Lapillus mixtures). The so-treated MLLs are then used as nutrient solutions for the anaerobic digestion (AD) of market wastes (MW) to optimize the C/N ratio. Moreover, during the anaerobic digestion, granular active carbon (GAC) is added in some reactors along with the feeding solution (substrate and pre-treated MLLs) to retain possible refractory or toxic compounds and to facilitate microorganisms’ activities by promoting the direct interspecies electron transfer mechanism. MLLs, used as nutrient solutions, lead to a stable AD of MW with a methane yield of about 0.260 NL/gVSadded. GAC is proved to be also efficient in the enhancement of the methane production as higher methane yields (about 0.302 NL/gVSadded) are obtained in reactors where it is added as a supplement.

The global increase in world population is followed with a rise in waste generation and energy needs in various sectors. Organic waste, also known as biomass, is the most substantial contribution of the waste generation and it also can be utilized in energy generation. Therefore, the purpose of this study is to analyze the syngas production from co-gasification using Renewable Densified Fuels (RDF) with gasification temperature, lower heating and gas emission values, on the performance of the biomass co-gasification process in an open-top downdraft fixed bed gasifier. In this study organic waste used woods, coconut fibers and rice husks in pellets to blend the compositions of raw materials during the co-gasification process. The method used is the co-gasification technique with feed pellets WCF (wood-coconut fiber) and RH (rice husk) in various compositions, for example: 100% WCF, with 0% of RH, 75 WCF: 25 RH, 50 WCF: 50RH, 25 WCF: 75RH and all 100% RH with 0WCF. Furthermore, the syngas testing was directly measured on the burner with TCD type Shimadzu 8A gas chromatography. The result showed that the highest reactor temperature in the pyrolysis zone is 700 °C–900 °C which was significantly stable at 800 °C with oxidation temperature of 1000 °C–1100 °C. Furthermore, the result of the synthetic gas showed that the highest lower heating value of 100% WCF pellet composition at 3.582 kJ/Nm3 and lower heating value of RDF blending composition (75:25) at 3.392 kJ/Nm3. The increase in pellet fuels also leads to a rise in the LHV syngas value. These results produced a visually low tar content and ash particles in all compositions by approximately 30–35% of the initial mass, with the lowest ash in 100% WCF pellets composition at 0.25 g.

Landfilling biodegradable waste is an important source of global greenhouse gas (GHG) emissions. Among the several types of landfill, limited-controlled landfill is a common method used to dispose of domestic solid waste, especially in developing countries. However, information about GHG emissions from limited-controlled landfill sites has rarely been reported. In this study, the GHG emissions from a typical limited-controlled landfill site were investigated under a regular period for one year. The number and positions of static chambers were arranged according to the guidance on Monitoring Landfill Gas Surface Emissions by the UK Environment Agency to obtain representative data from the heterogeneous surface of the landfill. Inverse distance weighting (IDW) was applied to evaluate and visualise the GHG emissions from the whole landfill surface based on the measurements of distributed static chambers. As an important GHG source of the landfill site, the emissions from the landfill leachate treatment plant were also measured. The results revealed that CH4 and N2O emission fluxes from the landfill area were 1324.73 ± 2005.17 mg C m−2 d−1 and 2.16 ± 2.33 mg N m−2 d−1, respectively, and the fluxes from the leachate treatment plants were 23.92 ± 29.20 mg C m−2 d−1 and 16.40 ± 16.89 mg N m−2 d−1, respectively. CH4 and N2O releases preferred to present spatial heterogeneity, while temporal heterogeneity was expected to exist in CH4 and CO2 emissions. The annual GHG emissions from the limited-controlled landfill was calculated to be 1.078 Gg CO2-eq yr−1, which was the least among all types of landfill sites. In addition, the GHG emission factor was 0.042 t CO2-eq t−1 waste yr−1 which could not be ignored compared to the sanitary landfills. Therefore, it is advisable to give more attention and determine a potential solution for reducing GHG emissions from limited-controlled landfill sites. Keywords: Greenhouse gas emission, Methane, Nitrous oxide, Limited-controlled landfill, Landfill leachate, Emission factor

Moina macrocopa (Straus, 1820), was cultured on different animal manures (i.e. chicken manure, Pig manure and cow manure) and food waste to detect the influence of these food sources on its mass production. Then M. macrocopa was used as feed for the rearing of Pagrus major larvae and its effects on their performance was studied. At first, the experiment was carried out for 21 days to identify the best culture medium for M. macrocopa. Food waste treatment resulted in higher density of M. macrocopa compared to other animal wastes. The percentage of unsaturated fatty acids was also significantly higher in the food waste treatment. Subsequently, we compared the effect of M. macrocopa cultured on food waste, Artemia and artificial diet on rearing the larvae of Pagrus major, red sea bream. The feeding time differed for each treatment, but the feeding number and amount were adjusted for all treatments. Results showed that larvae fed with M. macrocopa showed higher survival rates, growth rates, stress tolerance rate and DHA/EPA ratio than larvae fed with Artemia and artificial diet. The present results revealed that M. macrocopa cultured on food waste has an outstanding food potential and a probable substitute for Artemia. Keywords: Moina macrocopa, Food waste, Fatty acid content, Artificial diet, Pagrus major, Larvae

The directive to close the dumpsite in Kisumu, Kenya has made the search for alternative solid waste treatment and disposal technologies urgent. The aim of this research is to support the decision-making process by analyzing multiple socioeconomic and environmental parameters of salient solid waste treatment options. We used multi-criteria analysis to assess and compare anaerobic digestion, sanitary landfill, bioreactor landfill, and incineration. Informed by field observations and interviews, the chosen assessment criteria were economic costs, electricity generation, GHG emissions, land footprint, air pollution, soil and water contamination, and compatibility with recycling efforts. A literature review yielded quantitative and qualitative data that supported the analysis and the ranking of solutions according to performance in each criterion. Our analysis shows that anaerobic digestion is a suitable solution for Kisumu, due to its reduced environmental impacts, production of electricity and fertilizer, suitability to treat the large organic waste stream generated in the city, and compatibility with independent recycling activities. Landfilling represents a cheap solution; however, previous failed initiatives indicate that finding available land close to main waste generators is a challenge. Incineration is costly and requires advanced air quality control equipment and high combustibility of incoming waste, which is not the case for Kisumu, where over 60% of waste stream is organic/wet. Our results and recommendations are targeted for the Kisumu case, but they can be relevant for researchers and policymakers elsewhere, especially in low- and middle-income cities facing similar challenges.

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG [Abstract] Local composting (household, community and small scale applications) is considered a sustainable option for bio-waste recovery and is receiving increasing demand from society. Higher education institutions are no exception, but detailed and comprehensive long-term studies on composting programs on university campuses are lacking. The local composting program of the University of A Coruña (UDC) offers a decentralized service for the treatment of food waste from 11 university canteens using static and dynamic composters located in 9 different composting areas. Considering the three pillars of sustainability, this work describes the characteristics of the different composting technologies used and their investment and operational costs, the routine monitoring process and product quality, the integration of the composting systems as living labs for biotechnology and environmental engineering courses, and the use of compost in the university vegetable gardens. The agents involved in the project are the canteen staff, the university gardening company, external composting operators, university researchers and teachers, sustainability scholarship students and volunteer people. Organic waste is usually delivered directly by canteen staff to composters. The gardening service provides green waste from UDC campus (crushed pruning) that is used as bulking material. The monitoring and maintenance of the composting areas is currently in charge of external staff provided by a local NGO dedicated to cooperation and job reintegration of the unemployed. The service also allows the incorporation of volunteers and scholarship students as operators and process monitoring supervisors. The main result of this project was the prevention of a large amount of waste that did not require collection and transportation, or disposal or incineration. This is being done in an economically sustainable way, as decentralized composting costs have been lower than the average costs of municipal solid waste treatment in the region. The lower investment costs of static composters largely offset the higher labour costs and result in lower overall costs than those of the dynamic composter. The dissemination of composting practice to society was another important outcome of the project.

Earthworm bio-composting is an environmentally friendly way of processing agricultural organic waste, especially cow manure. In order to observe the temperature, humidity and conductivity of cow manure during the biological composting process of earthworms, a composting data collection system was designed to collect the above data. The experiment was carried out in an earthworm breeding farm in Changqing District, Jinan City, and lasted for 50 days, from October 21, 2020 to December 10, 2020. The experiment data can be used for data comparison with conventional composting, and can also provide a reference for the exploration of the earthworm composting process.

This paper evaluates the behavioral spillover effect of organic waste sorting on households’ waste reduction. We use an administrative household-level dataset on residential waste from a Swedish municipality. To identify the spillover effects, we utilize a natural experiment triggered by the staggered implementation of a policy that introduced home-based organic waste sorting bins. We find a substantial positive spillover effect of waste sorting on waste reduction. The effect, however, disappears over time.

The Green Revolution faced a great cost to meet ever-increasing demands for food, where indiscriminate use of agrochemicals resulted in non-friendly habitats. Therefore, the development of a sustainable approach to better crop production of onion seeds (Allium cepa L.) is very crucial. It is time to use organic waste as a replacement for agrochemicals by using arbuscular mycorrhizal fungi (AMF) and Trichoderma. Fish waste as representative of food waste acts as a leading cause of contamination of the environment. The interaction of AMF and Trichoderma viride on biomass, total soluble protein, mycorrhizal colonization, amino acids, phosphatases and phosphorus and nitrogen contents of onion plants grown in fish waste amended soil was studied. Fish waste has caused a slight increase in onions biomass, total free amino acids, and soluble protein content while with AMF and T. viride dual inoculation more increments were recorded; such increases were related to an increase in mycorrhizal colonization. T. viride application significantly increased the mycorrhizal colonization levels, but these were significantly reduced with waste addition. Analysis of amino acids in plants showed that their concentrations had changed as a result of waste addition combined with AMF and/or T. viride. The effectiveness of fish waste combined with low cost and health/environmental safety leads to a prediction that the introduction of fish waste coupled with fungi will become a more popular feature of agriculture in the future.

Anaerobic digestion is a well-established technology which valorises organic wastes to produce renewable energy as biogas. The ammonia released during this process can be inhibitory if it exceeds the threshold concentration. Additionally, ammonia is a harmful environmental pollutant and also a renewable source of energy, thus establishing a need for the recovery of ammonia. Gas-liquid stripping is one such widely researched technology to recover ammonia from wastewaters. However, there have not been any reviews focusing solely on the application of stripping to recover ammonia from the anaerobic digestate of organic wastes. This study reviews the current state of research in this field, focusing on the factors affecting the ammonia recovery, stripping column designs and linking of an anaerobic digester to a stripping column. An overview of the work done on the modelling of the ammonia stripping from digestate is also included. This review offers a direction for further research in this field; namely experimental and modelling studies on i) the effect of digestate composition on ammonia recovery and ii) the effect of stripping gas on ammonia removal. ispartof: Renewable & Sustainable Energy Reviews vol:143 status: Published online

A circular economy is an economic system aimed at minimizing waste and making the most of resources. Anaerobic digestion (AD) is a technology of great interest for the circular economy approach since it combines the treatment of high organic load wastes with the production of energy vectors (EV): biogas and biohydrogen. In this chapter, a brief description of the AD process characteristics is presented, including the two main configurations that lead to the production of the aforementioned EV: the single-stage process for methane-rich biogas generation and the dark fermentation process to generate hydrogen-rich biogas, together with volatile fatty acids (VFAs). Moreover, an overview of the production yields of both EV from different organic wastes generated in urban areas and rural zones with agro-industrial activity is addressed. Likewise, the use of VFAs for the generation of high value-added products through biorefinery processes is also reported. Among these products, polyhydroxyalkanoates should be highlighted. This option promotes the production of biobased and biodegradable bioplastics from organic wastes as a sustainable route and an attractive alternative to petroleum-based plastics. It is, therefore, an option framed in the context of both the circular economy and the green economy.

Cost-effective complete mineralization of recalcitrant organic waste pollutants from industrial effluents is a serious issue before environmentalists today. These organic wastes are discharged from chemical industries, refineries, and others, such as mining, paint industries, chemical and mineral extraction, and oils, in effluents that can be fatal and carcinogenic to humans. Generally, wastewater pollutant degradation is done by a physical, chemical, or biological method. Biochemical methods have been adapted for removing these organic pollutants. The bioremediation process does not generate by-product pollutant, making it a promising sustainable and cost-effective technique for the management of organic waste. In this chapter, we briefly discuss the available physical, chemical, and bioremediation techniques for handling organic pollutants.

Increasing urbanization and improper waste treatment techniques lead to unsustainable route of waste disposal in energy constrained communities. A more promising way of treating such organic waste is anaerobic digestion (AD), which is less energy intensive than aerobic digestion. The AD process in association with different types of bacteria helps in facilitating the phenomenon of direct interspecies electron transfer (DIET). Waste to energy technology integrated with DIET is largely unexplored. DIET also occurs naturally in several anaerobic digesters treating organic wastes. DIET may also be facilitated in anaerobic digesters through external amendments such as use of nonbiological, organic (biochar, activated carbon, carbon-based nanomaterials, carbon cloth, graphene, fullerenes, carbon nanotubes, conductive polymeric material, etc.), or inorganic (magnetite [Fe3O4], stainless steel, zero valent metal and metal oxide based nanoparticles) conductive materials (CM), for treating complex as well as concentrated wastes (sludge/agrowaste/solid organic waste). By using DIET, the requirement of reduced hydrogen or formate is sidestepped, somewhat the bacteria exercise cell-to-cell syntrophic relation for transfer of electrons. Supplementation of CMs further increases the biogas yield. However, certain inhibitors of AD such as ammonia, phosphorous, sulfide, metal ions, and heavy metals disturb the methane generation and overall process stability. DIET via CM has proved to be more effective in process enhancement, stability, and efficient methane recovery from the anaerobic reactors.

With the increasing rate of consumption of seafood globally, this industry creates a large volume of waste generation that is also rising and which often contains high-value substances. By-product/waste production from harvesting to end of consumption represents around 50%–70% of the total weight. Valorization of this biodegradable waste to obtain new industrial products has offered an environmental and economic solution to this problem. Among the different value-added products, gelatin from the seafood waste has received considerable attention due to its common usage in the food, pharmacology, and photography industries. While the utilization of fish gelatin has been subjected to a wide range of research, there remain gaps in the sustainability of the utilization of seafood waste for gelatin production. This chapter aims to address these challenges which limit its extensive application and suggest possible solutions to the aforementioned gaps in the sustainability of fish gelatin production. These approaches will be useful to researchers and industry practitioners who require information about processing, sustainability, and potential usage of fish gelatin in different fields.

Solid waste management is an important environmental and public health challenge, particularly in the developing world. This chapter highlights the importance of organic waste recycling using insects, which can subsequently be utilized as an alternative animal feed or even human food ingredient. In addition, biowaste conversion by exploiting insects is found to be environmentally more beneficial (reduced greenhouse gas emissions) than traditional waste handling, such as composting. Thus, organic waste valorization via insects could be a sustainable measure of biowaste treatment as it generates novel nutrient sources while posing a minimum threat to the environment. Characterizing biowaste as an insect rearing substrate, examining the potential role of the insect gut microbiota on waste degradability and insect biomass and quality, and identifying environmentally friendly residue handling approaches are some of the critical aspects for insect-based biowaste recycling in the future.

An increasing fossil fuel combustion raise the environmental concerns in terms of environmental pollution and climate change. Biogas is a byproduct of microbial metabolism. It is a sustainable fuel made of organic waste such as biomass and may reduce the global demand in fossil fuels. Its methane (CH4) content usually reaches 50%–70%, while its second most abundant component is carbon dioxide (CO2). In order to increase the caloric value of biogas, the methane content needs to be increased through an upgrading process. In this chapter, a possibility of using electrochemical methods to upgrade biogas by removal of its two major problematic compounds will be discussed. This chapter will focus on electroreduction of carbon dioxide (CO2), which is the second major compound in biogas, as well as electrochemical oxidation of hydrogen sulfide (H2S), which is its most corrosive component. Basic fundamental aspects, electrocatalysts, electrolyzer, and fuel cell designs, as well as challenges for further development and industrial applications toward electrochemical biogas upgrading will be discussed.

Although industrialization has been a boon to our economy and self-sufficiency, yet it accompanies a major drawback of generation of a huge amount of wastes as well as pollutants that accumulate in soil and aquatic systems, eventually contaminating and degrading the ecosystem. Moreover, the ever-increasing human population is making the situation worse. It is therefore a great challenge to manage the rapidly generating enormous amount of organic wastes and the accompanying pollutants. In this respect, biodegradation and decontamination of organic waste by employing microbial inoculants is an eco-friendly and cost-effective sustainable solution. Although the concept of biodegradation and decontamination by microbes is not new, however, it is yet to reach its full application potential. In spite of the promising response of microbial inoculants under laboratory/controlled conditions, a large field-scale application has shown limited efficacy, possibly due to the complex nature and nonsegregation of wastes. Both the waste decomposition through composting and waste decontamination through bioremediation rely on active microbial participation where they perform complex multistep pathways to achieve the final product. Henceforth, improving our perception of the microbial mechanisms and their interactions with organic waste material is the key requirement for harnessing the full potential of microbial technology in maintaining sustainability of the environment. This chapter presents an overview of the current researches on microbial inoculation as a way forward to achieve sustainability in managing overwhelming quantity of organic wastes and to achieve clean environments heavily affected by pollution. Furthermore, the potential of vital processes employed by the microorganisms for sustainable development and environmental management are also discussed, followed by their future prospects.

Available current literature is reviewed on the use of biochar as an additive to manure or alike organic waste materials. The diverse manure substrates are valuable organic fertilizers and can be further processed through composting and anaerobic digestion. However, physical properties, chemical composition and microbial population are hardly optimal but require adjustment and modification. To this end, biochar is a well-suited amendment. Different uses of biochar are explained. These are the use as feed additive for livestock and as an amendment to bedding material. Additionally, biochar is used as a bulking agent for manure handling, storage and further use, to modify manure composting as well as anaerobic digestion for biogas formation. Not last, the properties of biochar to retain nutrients in manure, thus enabling the subsequent use as slow release fertilizer, and for the immobilization of contaminants and pathogenic organisms are presented.

This chapter aims to examine the composting of biowaste as a suitable bioremediation method of contaminated sites with a focus on organic contaminants. The chapter analyzes different approaches in bioremediation practices through composting or land farming combined with composting of biowaste taking into considering the main organic waste streams such as municipal waste (food and garden wastes), agricultural waste, or sewage sludge. The use of compost as cosubstrates facilitates the bioaugmentation and biostimulation processes. These bioremediation practices are applied to sites contaminated with polycyclic aromatic hydrocarbons, pesticides, and petroleum products. Such applications stimulate better organic waste management practices combined with cost-efficient solutions for remediation of polluted sites. However, the performance of composting practices in soil bioremediation relies on several in situ factors. Current challenges, best practices, relevant case studies, and future prospects are further highlighted based on the literature review to reveal the state of the art on this topic.

The identification of novel waste management strategies is pivotal in establishing the circular economy for low-value organic matter. Conversion of organic refuse by saprophages offers a promising alternative for nutrient recovery from organic waste and has been identified as a sustainable upcycling alternative of protein production for humans and animal feed. Black soldier fly (BSF) larvae (Hermetia illucens) can grow on a wide variety of organic materials during their development from eggs to pupae and have been used to convert organic waste of different origin into high-value compounds and compost. The purpose of this research was to understand the potential use of BSF larvae for upcycling municipal sludge and the link between substrate and larvae composition, with particular attention to the change in proteins. Sludge (S)–containing media (50%) was used for larvae growth in combination with different proportions of brewery spent grains (B), coffee waste (C), and whey (W). Larvae size and weight, in addition to protein and lipid content, were measured at different stages of the larvae growth to assess their suitability for animal feed and product extraction. BSF larvae completed their development on all media with the exception of that containing a high percentage of whey (S5BCW3, S:B:C:W 50%:10%:10%:30%). Significative differences (p-value 0.05) between the control and media containing 50% wastewater sludge and 50% brewery by-products (S5B5) or high content of brewery spent grains (S5B3CW, S:B:C:W 50%:30%:10%:10%).

Compared to conventional petroleum-based polymers, biopolymers like polyhydroxyalkanoates are a promising alternative as raw material for manufacturing of plastics. One way to reduce the microbial PHA production costs is to use organic wastes from agriculture and food industries, which contain a wide range of carbon sources. Two organic waste carbon sources are fructose, present in fruit juice waste and acetate, present in waste from wine or biogas production. Simulations using kinetic models can help to reduce the range of optimal substrate combinations and thus prevent time-consuming and costly experimental investigations. This contribution outlines an extended hybrid cybernetic model for the polyhydroxybutyrate production in Cupriavidus necator growing on fructose, acetate, and nitrogen. Data from bioreactor experiments are used for the adjustment of the kinetic parameters and for the validation of the hybrid cybernetic model. The new model is able to precisely predict the dynamic behavior of hydroxybutyrate while co-feeding with fructose and acetate. Finally, our model is used in a computational study to analyze different initial carbon/ammonium ratios and oxygen partial pressures with respect to the maximum hydroxybutyrate concentration.

One of the most promising technologies for production of biogas from organic waste is anaerobic digestion (AD). As the experiments related to AD are time-consuming, labour intensive, and expensive, numerical simulations are important, because they provide a useful tool towards developing optimized and stable AD processes. This paper focuses on the optimization of the AD process in order to maximize biogas production from cattle manure by determining optimal values of process parameters. For this purpose, a modified mathematical model has been developed to simulate AD at various temperatures and pH values by considering appropriate inhibitions, detailed pH and temperature effects on microbial growth, and temperature dependencies of liquid-gas mass transfer coefficients, dissociation constants, and Henry’s law coefficients. This model was applied for the simulation of AD in a batch reactor and verified with experimental data. By using this model in an optimization procedure, the optimal values of pH and temperature, both acting as design variables, were determined. By engaging a gradient-based optimizer, based on an adaptive approximation method, it was shown that a reliable AD model can be used very efficiently in gradient-based optimization. The optimization process proved to be efficient, stable, and starting-point-independent; the engagement of numerical differentiation did not cause any problems. The results show that at optimal process conditions the production of CH4 is significantly improved in comparison to conditions often given in the literature. The results obtained confirm the usefulness of the proposed approach, which can easily be adapted or upgraded for complex substrates and other reactor types.

This chapter concerns residual organic substances from foodstuffs. In this perspective, domestic, agricultural, and industrial environments produce organic waste, which should be collected, stored, and recycled properly in order to avoid environmental pollution. In this context, experimental observations showed that biocatalysts are efficient to transform organic waste to produce biogas and organic, and mineral fertilizers for agriculture. These types of fertilizers of biological origin are suitable because they cannot harm the environment and mankind. This ongoing project is suitable to clean up the environment and improve agriculture, particularly in the Congo (RDC). In one of our publications, we proposed enzymatic reactions in the production of biomethane from organic waste, with an emphasis upon reaction mechanisms to show the generation of intermediate and final products in the reaction medium. Indeed, knowledge of the reaction mechanisms helps to select proper organic residues as starting materials. For instance, organic residues rich in carbohydrates are suitable for the biomethanation process because it has been observed that the major part of the methane comes from acetate, and this compound is obtained from the enzymatic degradation of glucose

Waste is produced in the process of people’s lives and production that pollutes the environment. Some of the waste contains a lot of organic matter. Through some treatment methods, this organic matter can be extracted to produce clean renewable energy, such as hydrogen energy. Biohydrogen production technology is a promising method of hydrogen production. The effective treatment of organic waste is the premise of the industrialization of hydrogen production, and optimization of the process and technology of hydrogen production is the basis of the industrialization of hydrogen production. Therefore, it is necessary to have a solid grasp of progress in the research of waste to biohydrogen, a clear understanding of its challenges, and a clear direction of its prospects. This chapter aims to introduce progress in the research, challenges, and the development prospects for biohydrogen production from waste. According to the results, it may be concluded that research in biohydrogen production from waste is still in the primary stages of exploration and faces various problems and challenges. Nevertheless, biohydrogen production technology is one of the best methods for the rational use of waste.

Global increases in food waste utilization and simultaneous protein shortages have recently spurred interest in invertebrate agriculture as a bioconversion methodology. This interest largely stems from the fact that many invertebrate species can reduce organic waste through consumption and convert the waste into high protein biomass. This chapter will explore the organic waste reduction and bioconversion capabilities of several common invertebrate species including black soldier fly larvae, housefly larvae, and earthworms and some less conventional species, such as cockroaches. Specifically, this chapter will show not only that waste reduction and bioconversion capabilities are species dependent but also that diet composition and cultivation conditions can affect insect/worm development time and final chemical composition. Each section of this chapter will include a discussion regarding the nutritional content of the insect species, its viability as feed source for humans/animals, and the efficacy of possible industrial rearing practices.

The circular bioeconomy aims to use resources in the most efficient manner. This includes the conversion of waste and residues, such as organic wastes, into new materials. However, the heterogeneity of organic wastes makes it very difficult to process. In this context, anaerobic digestion has emerged as a core technology to transform this complex organic waste (urban, agro-industrial, or livestock waste) into intermediates that can be further valorized as new commercial products in the so-called waste-to-value biorefineries. Anaerobic digestion initially converts waste of varying compositions into homogeneous intermediates such as biogas (50%–70% CH4) and digestate (rich in nutrients). Applying this organic waste biorefinery concept based on anaerobic digestion, biogas can be cost-effectively converted into biomethane using membrane technology which has benefited from recent advances in material science. Additionally, biogas represents a promising feedstock for the production of new materials such as ectoine and polyhydroxyalkanoates that have the potential to replace fossil-based products. Finally, algal photobioreactors allow for the effective recovery of the nitrogen and phosphorous contained in the digestate. These nutrients are accumulated into the algal biomass that can be further valorized as new bioproducts, thus contributing to create a circular bioeconomy.

With the developing economy and the improving living quality, quantities of municipal solid waste (MSW) generated without improper treatment, which resulted in the wastage of resources and environmental pollution. In order to utilize organic waste in an economic-practical way, sustainable technologies, missions and policies were essential to ensure sustainable economic development. Therefore, circular bio-economy was proposed under this background, which plays an important role in the generation of valuable biological products and sustainable economic development. In recent years, targeted biological technologies are applied to recycle organic waste, obtain products, and collect energy according to the types of organic waste and their own properties at an industrial scale, which is considered as biorefinery. Whereas, there are some challenges in biorefinery in China, which are attributed to limited budgets, infrastructure and maintenance, types of organic waste without classification and models of farming and feeding. Therefore, more efforts in research are essential for improving and making better use of these biological technologies in actual production. Additionally, the policy proposed by government plays an important function in developing biorefinery. To further, for the sake of satisfying the needs of current technological innovations, combining waste biorefinery methods with a new business model to meet stable market demand under the leadership of the China policy, can provide safety, assurance, and the sustainable economic development.

Because of the quick industrialization and population explosion, the people of India migrated from villages to cities which resulted in the generation and accumulation of a huge amount of solid organic waste like vegetable waste, food waste, etc. daily. With a geographical area 2163.48 km2 Gandhinagar is the well-known city of Gujarat state (India) and lies between 72.3’–73.7’ East (Longitude) to 23.0’–23.6’ North (Latitude). The population of Gandhinagar is approximately 206,167. A described study was conducted for the isolation and identification of bacterial population from the compost prepared from municipal organic waste collected from different regions of Gandhinagar city. Compost, as improved organic matter, can be effectively used for improving soil quality in many ways for environmental and economical sustainability in agriculture. Composite with different organic waste (vegetable waste, food waste, municipal solid waste, and farmyard manure) exhibited a total of six different bacterial strains. 16S rRNA genes were identified from DNA sequencing, with that they mainly belonged to three genus groups such as Staphylococcus, Streptomyces, and Bacillus. Physicochemical characterization of 90 days finished compost is evidence that all parameters reached relatively stable levels and can be acceptable to use as a fertilizer and reveal the comprehensive mechanism of these bacteria on compost quality.

This chapter reviews the current knowledge about production and characterization of biogas as a sustainable energy source. Technology for biogas production is well established and principally employed for the generation of sustainable electricity from different feedstock as well as for the environment-friendly disposal of organic waste. Biogas, the mixture of various gases led by methane, is produced from the digestion of organic matter present in different feedstock such as agricultural, urban, and industrial waste under anaerobic conditions by consortia of microorganisms. The anaerobic digestion process has been well known since ancient times. In our time, the biogas sector has swiftly grown as it has neither any geographical limitations nor required any dedicated technology for producing energy, so biogas plants have been installed as a progressive bioenergy industrial unit worldwide.

The rapid increase in population and industrialization has led to an increase in pollution and also the contamination of water resources. Since the removal of waste became a necessity due to an increase in pollution, anaerobic digesters (ADs) were brought into the picture. An AD is a system that is used to convert biodegradable waste into renewable biofuels and by-products. Anaerobic digestion has proven to be one of the most reliable processes with a huge potential in the immediate future. The underlying issues such as sanitation, renewable energy, waste management, health, and biofertilizer production have caused the widespread application of this process in order to eradicate them. In the recent past biomethane has emerged as promising gaseous fuel utilized in cogeneration and trigeneration powerplants. One of the major products of AD is methane, the methanogenic microbial community plays an important role in this anaerobic bioreactor. This process mainly aims at reducing the hazards of wastes on the biosphere. This chapter mainly includes the role of microbes in the AD and their mutualistic behavior resulting in the decomposition of complex organic compounds into simple chemically stable compounds like carbon dioxide and methane. This chapter comprehensively covers the topics to provide complete knowledge, to the readers, of the fundamentals of anaerobic digestion and bioenergy conversations. It includes the basics of different AD designs as well as important major factors involved in methane production and responsible for changes in the population dynamics of methane production. With this chapter, a thorough understanding of the fundamental principles of AD will help readers to perceive new aspects of bioenergy conversions.

Huge quantities of organic waste materials are generated annually in the United States and elsewhere leading to the age-old problem of how to dispose of these materials in an economic and environmentally friendly manner. The problem is exacerbated by increasing regulations on disposal of wastes and the difficulties involved in opening new landfills. Composting of biodegradable organic wastes presents at least a partial solution. Composting in its basics is simply the managed microbial decomposition of organic wastes to produce a more stabilized end product that is acceptable for use as a soil amendment in multiple settings. Composting systems range from simple backyard piles and bins to highly engineered computer controlled mechanized processes. This chapter introduces the basic concepts of the composting process and describes characteristics of finished products.

Ever since the inception of humans on the earth, the population has never stopped increasing. With the increase in population, the human societal system took many twists and turns, with modernization being an essential requisite to most countries. Therefore, with this change in lifestyle patterns and population boom, solid waste generation was an inevitable anthropogenic activity. Until the last few decades, the world could never imagine solid waste would become such a severe threat, and unmanaged landfills would be a significant contributor to greenhouse gas leading to climate change. Although solid waste management is a high priority sector today, many countries find it challenging to address this issue through a sustainable and practical approach. One of the major roadblocks is the unsegregated nature of solid waste, making it unsuitable for most available waste treatment technology. The problem increases manifold when the unsegregated solid waste contains higher moisture and organic content and has low calorific value. Black soldier fly larvae (BSFL) have recently been identified as effective agents for treating organic waste. The present study explores the potential of BSFL in decomposing the organic fraction from five different unsegregated municipal solid waste (MSW) compositions. BSFL successfully degraded and converted the compostable fraction from the unsegregated MSW into its biomass. BSF prepupae’s final weight varied between 158 and 241 mg/larvae for the five different MSW compositions. The protein content of the obtained BSF prepupae ranged between 26% and 31% on a dry weight basis. The chapter explains the kinetics of waste decomposition using BSFL, segregation of various fractions of MSW after treatment, and the revenue generation aspect of the proposed treatment technology. The present study is the first ever study on the application of BSFL as an agent for the treatment of unsegregated MSW.

Environmental problems have encouraged investigation of renewable energies. The organic waste treating through fast pyrolysis seems to be a highly promising option for decreasing pollutants. Olive pomace, a major source of waste in countries with high production of olive oil (mainly Spain, Italy, and Greece), is a clear target for valorisation. Dried olive pomace together with the ashes obtained during the drying process was blended to study the influence of the inorganic metals inherently present in the ashes (K, Na, Ca and Mg) for fast pyrolysis product distribution. The results determined that these metals increased yields of phenolic compounds until a maximum was reached, whereas carboxylic acid yield fell due to the action of metals. In addition, aromatic hydrocarbons and polyphenols were obtained for those samples with a large amount of ash. Moreover, the formation of organic acids, such as acetic acid, requires a smaller proportion of ash in the blend. Finally, it has been found that the ashes could be used as a catalyst for producing better quality bio-oil, thereby avoiding extra costs and thus valorizing the industrial treatment olive pomace., Los problemas medioambientales han fomentado la investigación de las energías renovables. El tratamiento de residuos orgánicos mediante pirólisis rápida parece ser una opción muy prometedora para la disminución de contaminantes. El orujo de aceituna, una fuente importante de residuos en países con alta producción de aceite de oliva (principalmente España, Italia y Grecia), es un claro objetivo de valorización. El orujo de oliva seco junto con las cenizas obtenidas durante el proceso de secado se mezclaron para estudiar la influencia de los metales inorgánicos inherentemente presentes en las cenizas (K, Na, Ca y Mg) para una distribución rápida del producto de pirólisis. Los resultados determinaron que estos metales incrementaron los rendimientos de compuestos fenólicos hasta alcanzar un máximo, mientras que el rendimiento de ácidos carboxílicos disminuyó por la acción de los metales. Además, se obtuvieron hidrocarburos aromáticos y polifenoles para aquellas muestras con gran cantidad de ceniza. Además, la formación de ácidos orgánicos, como el ácido acético, requiere una menor proporción de cenizas en la mezcla. Finalmente, se ha comprobado que las cenizas podrían utilizarse como catalizador para producir bioaceite de mejor calidad, evitando así costes extras y valorizando así el tratamiento industrial del orujo de oliva.

This chapter is focused on the preparation of low-cost and effective electrode materials which may facilitate the Volmer step of hydrogen evolution reaction to produce more hydrogen through a microbial electrolysis cell (MEC). Simultaneously the solid e-waste management for a better environmental scenario and wastewater treatment through the same MEC could be addressed. In most of the MECs, various operating parameters govern the performance in terms of rate of hydrogen evolution. The threat for e-waste generation has been alarming due to the inefficient reuse and recycle process. It has resulted in very crucial environmental problems and disposal issues. To overcome this problem, investigations into e-waste generated activated carbon with nitrogen doping for effective electrode material has been outlined, along with its use in MEC as an electrode material. Moreover, the wastewater containing organic waste will be the source for the hydrogen, thus resulting in simultaneous wastewater treatment and energy recovery through the proposed cost-effective MEC with e-waste utilization, as well as the production of the source of clean energy.

Myriad enzymes from various microorganisms (such as bacteria and fungi) have been studied for their potential role in the biodegradation of organic waste, which is generally synthesized in the form of surface-active compounds (SACs) called biosurfactants. Employing microbial biosurfactants/enzymes is an eco-friendly and cost-effective biotechnology that can advance the bioremediation process in the reduction of toxic pollutants. It also leads to harnessing novel useful compounds. More targeted research is needed on a working model for the treatment of organic waste–based remediation strategies. In this chapter, we address the current understanding of and advances related to biosurfactant applications in mitigating problems associated with organic waste.

Photocatalysis is an ecofriendly, green, sustainable, and promising technology for the degradation of many organic and inorganic water pollutants. The presence of organic waste contamination has created serious problems to human beings. The removal of organic pollutants from wastewater has been the matter of increasing attention in recent years. Dyes are one of the most common pollutants that come from industrial wastewater. Photocatalysis, due to its wide range of advantages, has been attempted for environmental remediation. Photocatalytic degradation of organic dye such as methylene blue, congo red, methyl red, etc., have paid much interest due to environmental impact. This chapter summarizes the treatment progress in wastewater and efficiency of homogeneous and heterogeneous photocatalytic processes. The photocatalyst surface modifications, kinetics degradation, reaction parameters, as well as the application of wastewater treatment are also discussed in detail.