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• Field experiment in mandatory recycling scheme tests effectiveness of door stepping. • Majority of households in mandatory recycling schemes separates waste correctly. • Minority of households is responsible for most miss sorting. • Door stepping does not influence behavior of households in mandatory schemes. • Door stepping can improve recycling behavior in voluntary recycling schemes. Household organic waste has great potential for closing nutrient cycles in agriculture. This requires proper waste separation by households. Personal communication at the doorstep potentially improves household waste separation behaviour but it is expensive and findings from existing research are mixed. Based on results of previous studies and from a quasi-experiment with non-equivalent groups design in two German municipalities, this paper argues that efficiency of personal communication depends on its context. It can positively influence behaviour when recycling is voluntary and participation rates are low. However, it has no significant effects if recycling is mandatory. One explanation could be different perceptions of recycling in mandatory and voluntary schemes. In voluntary schemes door stepping can activate the intrinsic motivation of households. In mandatory schemes, all households need to participate irrespective of intrinsic motivation. This research shows that this creates a situation in which a small share of households is responsible for almost all contamination. This can be overcome by considering extrinsic factors that affect recycling behaviour. The paper recommends further research to understand which combination of incentives, sanctions and information is efficient in affecting behaviour change in mandatory recycling schemes. [ABSTRACT FROM AUTHOR]

The intensive development of the polyurethanes industry and limited resources (also due to the current geopolitical situation) of the raw materials used so far force the search for new solutions to maintain high economic development. Implementing the principles of a circular economy is an approach aimed at reducing the consumption of natural resources in PU production. This is understood as a method of recovery, including recycling, in which waste is processed into PU, and then re-used and placed on the market in the form of finished sustainable products. The effective use of waste is one of the attributes of the modern economy. Around the world, new ways to process or use recycled materials for polyurethane production are investigated. That is why innovative research is so important, in which development may change the existing thinking about the form of waste recovery. The paper presents the possibilities of recycling waste (such as biochar, bagasse, waste lignin, residual algal cellulose, residual pineapple cellulose, walnut shells, silanized walnut shells, basalt waste, eggshells, chicken feathers, turkey feathers, fiber, fly ash, wood flour, buffing dust, thermoplastic elastomers, thermoplastic polyurethane, ground corncake, Tetra Pak®, coffee grounds, pine seed shells, yerba mate, the bark of Western Red Cedar, coconut husk ash, cuttlebone, glass fibers and mussel shell) as additives or fillers in the formulation of polyurethanes, which can partially or completely replace petrochemical raw materials. Numerous examples of waste applications of one-component polyurethanes have been given. A new unexplored niche for the research on waste recycling for the production of two components has been identified. [ABSTRACT FROM AUTHOR]

There is much organic waste that comes from by-products of agriculture and product processing, solid waste from livestock, and municipal waste. Conventional methods that are widely used for the treatment and management of organic fractions of waste are landfilling, composting, anaerobic digestion, incineration, gasification, and pyrolysis. Among the above methods, pyrolysis is a relatively simple, robust, and scalable technology for transforming diverse organic waste feedstock into renewable energy products. Recently, the electrochemical conversion of biochar into electricity in direct carbon fuel cells (DCFC) has also been investigated and shown to be feasible and highly efficient. This paper focuses on the utilization of organic waste as a fuel and the investigation of their characteristics during electrochemical reactions in molten hydroxide direct carbon fuel cells (MH-DCFCs). Organic waste of different origins (the food-processing industry, urban and suburban areas, municipal solid organic waste, sewage sludge) with diversified characteristics was used as the main feedstock. The lowest power density was determined for sewage sludge (5.1 mW cm−2), and the best results were obtained for peanut shells (53.14 mW cm−2). This study concludes that higher elemental carbon, lower ash content and the presence of reactive surface oxygen functional groups in biochar obtained from organic waste might contribute to better cell performance. Moreover, the research establishes the potential of carbonized organic waste as a prospective alternative fuel source for power generation in an MH-DCFC. [ABSTRACT FROM AUTHOR]

• First Multiple Linear Regression analysis of waste management systems in EU capitals. • Door-to-door bio-waste collection linked to higher overall dry recyclables capture. • On average, dry recyclables sorting doubled in capitals with door-to-door bio-waste collection. • Linkage between door-to-door bio-waste collection and boosted sorting needs further research. • Convenience, communication campaigns and system maturity likely causal factors. • Severe lack of available data hampers evidence-based EU policymaking. The European Union Waste Framework Directive revised in 2018 sets an ambitious target of recycling 55 percent of municipal solid waste by 2025. Separate waste collection is an important prerequisite for achieving this target, but progress is uneven among Member States and has slowed down in recent years. This makes it paramount to identify effective waste management systems to enable higher recycling rates. Waste management systems vary greatly within Member States and are established by municipalities or district authorities, making the city-level the ideal level of analysis. Based on quantitative analysis of data from 28 European Union capitals (pre-Brexit), this paper speaks to debates about the effectiveness of waste management systems more broadly and the role of door-to-door bio-waste collection in particular. Drawing on encouraging findings in literature, we investigate whether door-to-door bio-waste collection contributes to boosting the collection of dry recyclables such as glass, metal, paper and plastic. Employing Multiple Linear Regression, we sequentially test for 13 control variables including six related to different waste management system and seven controls related to urban, economic and political aspects. We find evidence that door-to-door bio-waste collection is associated with greater amounts of separately collected dry recyclables. Cities with door-to-door bio-waste collection, on average, sort 60 kg per capita per year more of dry recyclables. Although the causal mechanisms behind such a relationship need further investigation, this finding indicates that European Union waste management could benefit from a stronger promotion of door-to-door bio-waste collection. [ABSTRACT FROM AUTHOR]

From the perspective of resource recovery, this paper summarized the physical and chemical method ( evaporation method, the remove method, adsorption, membrane separation, magnesium ammonium phosphate precipitation) and recycling organic waste anaerobic biological method and other methods in the fermented liquid ammonia nitrogen form and its mechanism, analyses the anaerobic fermentation liquor pH, temperature, gas liquid ratio and suspended solids and organic matter, high concentration of ammonia nitrogen on the effects of the ammonia nitrogen recycling in view of the existing in the running cost is high, the adsorption capacity is small, membrane fouling and concentration ability is limited and difficult problems such as separation, puts forward the delve into a stable and efficient, low cost, convenient operation, nitrogen recovery technology and combination of the process and optimize the process conditions of research direction, in order to organic waste anaerobic fermentation contained ammonia nitrogen utilization to provide the reference. [ABSTRACT FROM AUTHOR]

Biofuel generated from different organic waste substrates has been described as a sustainable option to the rapidly exhausting fossil fuels. To worsen the dependence on fossil fuels, the price is skyrocketing daily attributable to high demand for it. The high demand and usage of fossil has therefore led to increased atmospheric CO 2 , which is a major greenhouse gas. Thus, the dire need to explore the production of biofuel, of which biohydrogen is one. In spite of the several benefits linked to the application of biohydrogen as fuel, its production is currently facing some levels of practical challenges, some of which include inadequate conversion of biomass and low rate of production. In order to enhance the production of biohydrogen, some influencing factors for production need to be optimized. In view of this, this review critically discusses fundamental factors that affect biohydrogen production, like substrate composition, pretreatment of substrates, physico-chemical parameters, etc. It was found that the key constituents in fermentative biohydrogen generation are carbohydrates while proteins are not that efficient. In addition, amongst metal ions like (Ni, Fe, Cu, Mg, Zn, and Na), Mg has been found to be one of the essential cofactors that activates more than ten enzymes involved in hydrogen fermentation. Biological pretreatment method for substrate has more advantages than others in terms of low-toxicity, mild reaction and low-cost. Reduction of partial pressure to an optimum level could enhance the yield of biohydrogen production. The integration of nanoparticles into the substrate to refill the biohydrogen (H 2) production is well-thought-out as a robust approach. Finally, this paper comprehensively discusses the effects of various nanoparticles on biohydrogen fuel production while it concludes by highlighting the future prospects. [Display omitted] • The effects of pre-treatment techniques for substrate are expatiated. • The recent development in the use of nanoparticles for biohydrogen production are discussed. • Influence of physicochemical parameters are presented. • The impacts of dark fermentation bioreactor design for biohydrogen production are reviewed. • Challenges with NPs application in dark fermentation are well discussed. [ABSTRACT FROM AUTHOR]

This paper was written based on an investigation of the statuses of rural living environments in China. By combining the main problems in rural living environments and the clean utilization of resources in China, this paper reviews and comparatively analyzes the development statuses of the clean utilization of three rural resource technologies, namely the resource utilization of rural organic waste, biomass fuel, and construction raw materials derived from organic waste. The feasibility was analyzed by considering the waste types, process paths, technical indicators, technical advantages and disadvantages, regional adaptability, and quantitative indicators. Thus, the direction of sustainable research is revealed. Furthermore, this paper proposes a specific and comprehensive technical scheme for clean resource utilization in terms of waste recycling and energy utilization in villages and towns in north and northeast China. This scheme integrates the technological utilization of multiple organic wastes fermentation, low-nitrogen combustion technology of biomass mixed materials, construction technology of active and passive village buildings, and informatization of rural living environments. It can supplement the technical scheme for improving rural living environments in north and northeast China, thereby accelerating the construction of infrastructure for such environments and laying the foundation for the synergy of living environment improvement and rural revitalization. [ABSTRACT FROM AUTHOR]

The article is devoted to the actual problem of utilisation of agricultural and industrial waste as a solution to the problem of replacing traditional energy sources. As an alternative fuel, researchers suggest using briquettes from biomass (leafy debris, waste paper, sunflower and buckwheat husks), as well as their combination with industrial waste (coal dust). The choice of these sources of raw materials is determined by their presence in the north-eastern part of Republic of Kazakhstan. Studies of the physical and mechanical and thermophysical characteristics of fuel briquettes from organic mass and bio-charcoal briquettes were carried out. The studies showed the following results: the moisture content of the samples we studied lies in the range from 3.86 to 8 %; ash content of briquettes from vegetable raw materials varies from 2.05 % to 3.6 %, combined briquettes from foliage and coal dust varies from 10 % to 14 %; average density values varies from 979.91 to 1172.63 kg/m3; mechanical strength is in the range from 90 to 100 %; the yield of volatile studied samples ranges from 9 to 21.4 %. Analysis of the obtained characteristics of fuel briquettes demonstrated that they meet the requirements of existing standards. Herewith, the lower calorific value of briquettes (15290-19048 kJ/kg) is comparable to the calorific value of coal from the Ekibastuz deposit. The authors studied the influence of the parameters of the briquetting process on the briquette's strength characteristics from leaves and waste paper, and obtained a regression dependence of these briquette's calorific value on their characteristics. The analysis of regression dependencies showed that the pressure and pressing time have the greatest influence on the briquette strength, and its composition, i.e., the ratio of leaves and waste paper in the feedstock, has the greatest influence on the lower calorific value. [ABSTRACT FROM AUTHOR]

In this paper were studied the physicochemical characteristics of organic waste generated in the municipality of Suchiapa, Chiapas, México. The objective was to characterize fruit and vegetable residues: pumpkin peel, tamarind peel, corn cob leaves and livestock fecal residues: cattle, sheep and poultry manure, to determine their optimal use in biogas and methane production. The parameters analyzed were humidity, ashes, pH, total solids (ST), total volatile solids (STV), carbon (C) and nitrogen (N), applying the methods of the Official Mexican Standards (NMXAA-016 to the NMX -AA-025). The results obtained from the calculation of STV, estimated a theoretical production of 850 L of methane/kg of STV through the use of pumpkin peel, being the best residue to guarantee biogas production. In this way, with the physicochemical characterization of the waste, it is possible to revalue their potential for the production of biogas. [ABSTRACT FROM AUTHOR]

The impact of landfills on the environment has come under increasing scrutiny in recent years due to the confounding effects of climate change and water scarcity. There is an urgent need to reduce from landfills the greenhouse gas emissions that cause climate change, and to provide effective treatment solutions for waste, thereby diverting it from landfills. With an estimated 80 million tonnes of plastic waste entering the world's oceans annually, the accumulation of marine plastic has become a global crisis. Plastic pollution threatens food safety and quality, human health and coastal tourism, and contributes to climate change. For these reasons, there is an urgent need to explore a bioplastic biorefinery process. This review paper examines the potential of organic waste as an alternative carbon source in the efficient and feasible microbial production of polyhydroxyalkanoate (PHA) and polyhydroxybutyrate (PHB), which are precursors for bioplastic. More specifically, this paper presents a concept for a bioplastic biorefinery from a technological perspective, based on data from previous studies. Biofuel production processes are also assessed with the aim of integrating these processes to construct a bioplastic waste biorefinery. Garden refuse and food waste have been shown to be feasible feedstocks for the production of PHA and PHB in singular processes. Diverting these wastes away from landfills will significantly ease the environmental impacts currently associated with their disposal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Artificial intelligence framework is developed to operation performance of AD plants. • The framework comprises RNN, NARX, SFLA models and sensitivity analysis. • Optimal operation strategy improves the productivity of biogas by 43% • Optimal feeding pattern during a four-day cycle needs feeding over the last two days only. • Optimised biogas is strongly influenced by the content of oats and catering waste. Despite the advantages of the Anaerobic Digestion (AD) technology for organic waste management, low system performance in biogas production negatively affects the wide spread of this technology. This paper develops a new artificial intelligence-based framework to predict and optimise the biogas generated from a micro-AD plant. The framework comprises some main steps including data collection and imputation, recurrent neural network/ Non-Linear Autoregressive Exogenous (NARX) model, shuffled frog leaping algorithm (SFLA) optimisation model and sensitivity analysis. The suggested framework was demonstrated by its application on a real micro-AD plant in London. The NARX model was developed for predicting yielded biogas based on the feeding data over preceding days in which their lag times were fine-tuned using the SFLA. The optimal daily feeding pattern to obtain maximum biogas generation was determined using the SFLA. The results show that the developed framework can improve the productivity of biogas in optimal operation strategy by 43 % compared to business as usual and the average biogas produced can raise from 3.26 to 4.34 m3/day. The optimal feeding pattern during a four-day cycle is to feed over the last two days and thereby reducing the operational costs related to the labour for feeding the plant in the first two days. The results of the sensitivity analysis show the optimised biogas generation is strongly influenced by the content of oats and catering waste as well as the optimal allocated day for adding feed to the main digester compared to other feed variables e.g., added water and soaked liner. [ABSTRACT FROM AUTHOR]

Plenty of organic waste has been produced from agriculture and rural areas in Beijing suburbs over the last decade, with the rapid development of urban agriculture. It is still lacking in the dynamics of the quantity, nutrient content, and the relationship between supply and demand over time. This paper aims to estimate the quantities and nutrient resources of straw, vegetable waste, abandoned branches of fruit trees, livestock/poultry solid and liquid manure, and kitchen waste in Beijing suburbs, according to the statistical yearbooks and literature. A systematic investigation was also made on the relationship between organic fertilizer nutrient inputs and crop nutrient demand. The results show that the production of organic waste and its nutrient production was declined yearly from 2010 to 2019, with 1.30×107 t and 2.18×105 t in 2010, respectively, while declining by and 62.3% and 71.8% in 2019, respectively. The ratio of specific organic waste and nutrients was ranked in the descending order of the livestock/poultry solid and liquid manure, straw, vegetable waste, abandoned branches of fruit trees and kitchen waste, but varied in different regions. Specifically, the Daxing, Shunyi, Pinggu, and Tongzhou districts shared the highest proportion of plant production waste and its nutrients in 2010, whereas, the Daxing and Miyun districts presented the highest proportion of breeding waste and its nutrients. Furthermore, the Pinggu, Shunyi, Daxing and Miyun districts showed the highest proportion of plant production waste and the corresponding nutrients in 2019, whereas, the Shunyi and Pinggu districts shared the highest proportion of breeding waste and the corresponding nutrients. The main producing areas of rural domestic waste were always in the Changping, Daxing, and Tongzhou districts. The amount of organic waste and nutrients in the Daxing district was the highest in 2010, at 2.45×106 and 5.10×104 t, respectively, the Pinggu district had the highest amount of nutrients, at 1.37×104 t, and the Mentougou district produced the least amount of organic waste. The amount of organic waste returned to the field gradually decreased over the decade, where the total amount of organic waste returned to the field in 2010 was 5.55×106 t and the total organic nutrient input was 1.51×105 t. The amount of waste and its nutrients returned to the field decreased by about 76.8% and 72.3% in 2019, compared with the distribution in 2010. The organic waste returned to the field was concentrated in the southeastern region in 2010, while the amount of organic waste returned to the field tended to be evenly distributed in 2019. There was a staggered trend in the matching between effective nutrient supply and crop demand in the returning fields under 50% chemical fertilizer rationing conditions. Specifically, the nutrient surplus was exacerbated in the Changping and Fangshan districts between 2010 and 2015, whereas, the nutrient deficit was found in the Huairou and Miyun districts in 2019. The nutrient overload of nitrogen and potassium was the most serious in the Mentougou district, while the phosphorus overload was serious in the Changping district. The nutrient overload areas should be controlled by the scale of the agriculture industry, considering the diversified high-value use of organic waste and the outward transportation of organic fertilizers, while the nutrient deficit areas can appropriately expand the scale of production for the nutrient utilization rate of organic waste. This finding can provide a scientific basis for green agricultural development, rational layout, and organic waste resource utilization. [ABSTRACT FROM AUTHOR]

The current methods of treating organic waste suffer from limited resource usage and low product value. Research and development of value-added products emerges as an unavoidable trend for future growth. Electro-fermentation (EF) is a technique employed to stimulate cell proliferation, expedite microbial metabolism, and enhance the production of value-added products by administering minute voltages or currents in the fermentation system. This method represents a novel research direction lying at the crossroads of electrochemistry and biology. This article documents the current progress of EF for a range of value-added products, including gaseous fuels, organic acids, and other organics. It also presents novel value-added products, such as 1,3-propanediol, 3-hydroxypropionic acid, succinic acid, acrylic acid, and lysine. The latest research trends suggest a focus on EF for cogeneration of value-added products, studying microbial community structure and electroactive bacteria, exploring electron transfer mechanisms in EF systems, developing effective methods for nutrient recovery of nitrogen and phosphorus, optimizing EF conditions, and utilizing biosensors and artificial neural networks in this area. In this paper, an analysis is conducted on the challenges that currently exist regarding the selection of conductive materials, optimization of electrode materials, and development of bioelectrochemical system (BES) coupling processes in EF systems. The aim is to provide a reference for the development of more efficient, advanced, and value-added EF technologies. Overall, this paper aims to provide references and ideas for the development of more efficient and advanced EF technology. [ABSTRACT FROM AUTHOR]

The inadequate disposal of organic waste threatens the global environment, social, and economic development, which needs to be paid great attention to. Using black soldier fly larvae to treat organic waste is conducive to the efficient transformation of organic matter. In order to more fully understand the differences and application scope of the system in the treatment of different wastes, in this paper, the key points of black soldier fly larvae transformation system were summarized, the points are the types and efficiency of transformed wastes, the changes of hazardous biological factors in the transformation process, the application value of black soldier fly larvae after transformation, and the utilization prospect of the transformed residue from the wastes. Through the literature review at home and abroad, the species and transformation efficiency of black soldier fly to reduce different animal and plant wastes were summarized. The application value and existing problems of the body obtained from the reduction of wastes by the black soldier fly and the the waste residue in the replacement of animal feed materials, plant fertilizer, and soil improvement were explored. Research progress on the treatment system of organic wastes by the black soldier fly on environmental protection such as control of hazardous matters and greenhouse gas was briefly summarized. The future research was also prospected: research on the effects of microbial fermentation of organic wastes, enzymatic degradation or combination of multiple wastes on the transformation efficiency of black soldier fly, research on the reduction mechanism of hazardous microorganisms contained in livestock and poultry feces by the black soldier fly, and the development or application of the effective components of antibacterial peptides and chitin in the black soldier fly larvae, especially research on the development of antimicroorganisms by the antibacterial peptides from black soldier fly larva protein under the trend of alternative antibiotics. [ABSTRACT FROM AUTHOR]

In the last decades, the worldwide interest in volatile fatty acids (VFAs) as basic elements for many industrial applications has been growing as fast as their market demand. Traditional production of VFAs from crude oil is unsustainable because of its environmental impact, therefore alternative solutions have been studied. The most promising solution has resulted in the VFAs production from organic waste based on biological processes thanks to the incoming environmental and economic benefits. In this scientific context, the state of current knowledge has not reached yet a satisfying level of comprehensiveness and it is mainly based on studies conducted at lab and pilot scale. Under the perspective to gain more knowledge and thus to promote an efficient as well as consolidated production of VFAs according to the key issues of the circular economy, a systematic and detailed study dealing with the impact of reactor configuration and relative operating conditions on biological VFAs production has been conducted. This step is a necessary condition to scale up the process and achieve its complete industrialization. According to this perspective and on the basis of the most recent findings from the international literature, the present review paper reports, as the main result of data elaboration, a novel one-to-one correspondence between organic wastes and reactor configurations having as target the VFAs yield enhancement. [ABSTRACT FROM AUTHOR]

Worldwide, the increase in land surface temperature has been attributed to the concentration of greenhouse gases. However, there is no record of timely information that shows which types of land cover relate to major increases in surface temperature. The main aim of this paper is to identify the specific sites in a landfill where biogas is released into the atmosphere. A second objective is to try to find a spatial correlation between the concentration of methane emitted to the atmosphere with the observed surface temperature gradients. The recoverable and fugitive methane fluxes were validated with in situ information, using a LICOR gas accumulation chamber. The surface heat estimate was obtained from the Split Window algorithm, using the TIRS sensor of the Landsat 8. With data obtained in previous studies, both in situ and remote, it was possible to spatially correlate the methane flux released into the atmosphere with the temperature distribution plume within the landfill. The importance of our research is related to the continuous need for surface temperature monitoring on the planet. The use of technological tools such as the one presented here reduces the cost and execution time of environmental studies. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is a technology that converts complex organic matter into another form of matter, from which energy can be more easily extracted. The stability and digestion of anaerobic co‐digestion with multiple raw materials as substrates is better than the performance of anaerobic mono‐digestion. In the past two decades, there has been a large amount of literature on how to improve the performance of methane production in the anaerobic co‐digestion process, but few systematic reviews have been conducted. This paper summarizes the factors affecting the development of anaerobic co‐digestion. The process parameters, substrate optimization strategy, microbial community, and model application for improving anaerobic co‐digestion performance were systematically analyzed. Methane purification technology and policies to support digestion projects are also discussed. At present, the technological process is basically mature, but the interaction between various parameters can be studied in depth. Methane purification technology expands the market for the biogas industry and increases its economic benefits. Policy is the key to promoting process technology and the methane market. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

The high amount of organic and inorganic wastes has increased the attention to new strategies aiming to reduce the waste disposals. Organic wastes, such as tomato wastes (TWs), are a good source from which the red color can be obtained. Among the different technologies, the geopolymers had been proposed as a powerful technology able to incorporate various kinds of wastes. In this paper, pure metakaolin and a mixture obtained by adding 10% of red TW‐derived (peels) are consolidated by alkali activation at room temperature, 40 and 60°C without the pigment extraction. Fourier‐transform infrared (FTIR) spectra confirmed the geopolymerization occurrences. Moreover, the obtained materials are analyzed for their conductivity and pH after the sample extractions at different times. The integrity tests assessed the resistance of the synthesized geopolymers and the presence of red tomato‐wastes led to a release of yellow organic hydro‐soluble compounds. Finally, the weight loss confirmed the integrity test. Indeed, there are no differences at 16 and 30 d. [ABSTRACT FROM AUTHOR]

High value-added products from organic waste fermentation have garnered increasing concern in modern society. VFAs are short-chain fatty acids, produced as intermediate products during the anaerobic fermentation of organic matter. VFAs can serve as an essential organic carbon source to produce substitutable fuels, microbial fats and oils, and synthetic biodegradable plastics et al. Extracting VFAs from the fermentation broths is a challenging task as the composition of suspensions is rather complex. In this paper, a comprehensive review of methods for VFAs production, extraction and separation are provided. Firstly, the methods to enhance VFAs production and significant operating parameters are briefly reviewed. Secondly, the evaluation and detailed discussion of various VFAs extraction and separation technologies, including membrane separation, complex extraction, and adsorption methods, are presented, highlighting their specific advantages and limitations. Finally, the challenges encountered by different separation technologies and novel approaches to enhance process performance are highlighted, providing theoretical guidance for recycling VFAs from organic wastes efficiently. [Display omitted] • The current status of research on VFAs produced from organic wastes was described. • Key factors have been discussed to enhance the performance of fermentation systems. • Key methods for intensifying the fermentation process have been explored and compared. • Feasible methods for VFA extraction are provided, focusing on integrated membrane technology. • Challenges and perspectives for the extraction and purification of VFAs are presented. [ABSTRACT FROM AUTHOR]

The transition towards a circular economy is becoming a priority in many countries globally. However, the circular bioeconomy has received relatively less attention. In South Africa, the valorisation of organic waste is a priority area as demonstrated by national goals to divert organic waste from landfill. To support the growth of the organic waste value chain it is important to gain an understanding of the different value chain actors and their activities. Through a series of semi-structured interviews across the industry, this paper unpacks the organic waste value chain including the roles of different actors and the interlinkages amongst them. Interviewed actors were those involved in the waste treatment sector, including consultants, composters and technology providers and installers. The value chain is characterised by a number of partnerships, including sub-contracting and outsourcing, which enable value chain actors to offer services that they do not necessarily have the in-house skills or capacity to deliver on their own. The majority of actors were not directly engaged in activities related to the treatment of waste, with many of them engaging in support activities to facilitate the treatment of waste. This finding may be attributed to the fact that support activities have relatively lower barriers to entry. This has the potential to create a bottleneck, in which there will be limited capacity for waste treatment as new entrants opt for engaging in support activities. Greater investment is needed from both private and public sources in the waste treatment sector, including support for new entrants. This investment will help enable the country to meet its goals for organic waste diversion whilst contributing to job creation. [ABSTRACT FROM AUTHOR]

The beetle Tenebrio molitor (T. molitor) contains a lot of protein, unsaturated fatty acids and trace elements, which can be fed and eaten after processing and can be used as a protein feed. The feeding habits of T. molitor are miscellaneous, whose feeding on different foods leads to different nutritional components in its body. The paper reviews the biological characteristics of T. molitor, the conversion effect of feeding different feeds, and the production and application of T. molitor in pigs, chickens, geese and other animals, to provide reference for feed selection and efficient utilization of T. molitor. [ABSTRACT FROM AUTHOR]

• BSFL can convert organic matter into animal feed, biodiesel, and chitin. • The BSF system produces lower carbon footprint compared to the other methods. • BSFL fed with high nutrient content and a low P:C ratio increased its production. • The BSF rearing system can be applied at all levels of society and technology. • The gut biome of the BSFL can be accounted for higher AMPs or survival rate. There are two major problems that we are facing currently. Firstly, a growing human population continues to contribute to the increased food demand. Secondly, the volume of organic waste produced will threaten human health and the quality of the environment. Recently, there is an increasing number of efforts placed into farming insect biomass to produce alternative feed ingredients. Black soldier fly larvae (BSFL), Hermetia illucens have proven to convert organic waste into high-quality nutrients for pet foods, fish and poultry feeds, as well as residue fertilizer for soil amendment. However, better BSFL feed formulation and feeding approaches are necessary for yielding a higher nutrient content of the insect body, and if performed efficiently, whilst converting waste into higher value biomass. Lastly, this paper reveals that BSFL, in fact, thrives in various ranges of organic matter composition and with simple rearing systems. [ABSTRACT FROM AUTHOR]

In general, composting is done both to reduce the amount of biodegradable waste, which would otherwise be sent to storage, and to obtain a material that can be used in agriculture. In this paper is studied the degree of compostability for 4 proposed recipes that contain biodegradable materials such as: garden waste and kitchen waste. By measuring the temperature of the mixture of organic materials, introduced in thermos vessels and aerated during 7 days, conclusions can be drawn about the degree of compostability of each sample. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) as a waste management strategy for the organic fraction of municipal waste (OFMSW) has received attention in developed countries for several decades, leading to the development of large-scale plants. In contrast, AD of OFMSW has only recently drawn attention in developing countries. This systematic review was carried out to investigate the implementation of AD to treat the OFMSW in developing countries, focusing on assessing pilot and full-scale AD plants reported in the last ten years. Studies that met the selection criteria were analyzed and data regarding operating parameters, feedstock characteristics, and biogas, digestate, and energy production were extracted. As outlined in this systematic review, AD plants located in developing countries are mostly one-stage mesophilic systems that treat OFMSW via mono-digestion, almost exclusively with the aim of producing electrical energy. Based on the analysis done throughout this systematic review, it was noted that there is a large difference in the maturity level of AD systems between developing and developed countries, mainly due to the economic capacity of developed countries to invest in sustainable waste management systems. However, the number of AD plants reported in scientific papers is significantly lower than the number of installed AD systems. Research articles regarding large-scale implementation of AD to treat OFMSW in developed countries were analyzed and compared with developing countries. This comparison identified practices used in plants in developed countries that could be utilized in the large-scale implementation and success of AD in developing countries. These practices include exploiting potential products with high market-values, forming partnerships with local industries to use industrial wastes as co-substrates, and exploring different biological and physical pretreatment technologies. Additionally, the analysis of capital and operational costs of AD plants showed that costs tend to be higher for developing countries due to their need to import of materials and equipment from developed countries. Technical, economical, and political challenges for the implementation of AD at a large-scale in developing countries are highlighted. • Anaerobic digestion (AD) of biowaste is gaining attention in developing countries. • AD plants in developing countries (DC) are mostly one-stage mono-digestion systems. • AD plants costs in DC are high due to their need to import equipment. • The challenges for the implementation of AD at a large-scale in DC were discussed. • Public-private partnerships are imperative to overcome these challenges. [ABSTRACT FROM AUTHOR]

The article reflects the problem of organic waste management and the composting methods used to improve the ecological situation of the environment. Some methods of composting organic waste of various origins are synthesized. Composting represents the process of decomposition and transformation of solid organic substances by microorganisms (mainly bacteria and fungi) into a stable material, which can be used (depending on the characteristics), in agriculture, instead of chemical fertilizers or in land improvement works (soil improvement). Only some methods of composting are characterized: the traditional method, worm cultivation and the method of effective microorganisms. All composting methods are welcome for agriculture because they solve complicated environmental problems: complete processing of organic waste, obtaining organic fertilizers and ecological agricultural production and improving the ecological situation. [ABSTRACT FROM AUTHOR]

The need of the hour relies on finding new but sustainable ways to curb rising pollution levels. The accelerated levels of urbanization and increase in population deplete the finite resources essential for human sustenance. In this aspect, water is one of the non-renewable sources that is running out very fast and is polluted drastically day by day. One way of tackling the problem is to reduce the pollution levels by decreasing the usage of chemicals in the process, and the other is to find ways to reuse or reduce the contaminants in the effluent by treatment methods. Most of the available water recycling or treatment methods are not sustainable. Some of them even use toxic chemicals in the processing steps. Treatment of organic wastes from industries is a challenging task as they are hard to remove. Electrocoagulation is one of the emerging water treatment technologies that is highly sustainable and has a comparatively cheaper operating cost. Being a broad-spectrum treatment process, it is suitable for treating the most common water pollutants ranging from oils, bacteria, heavy metals, and others. The process is also straightforward, where electrical current is used to coagulate the contaminates. The presence of carcinogens in these waste water increases the need for its treatment towards further use. The present investigation is made as an extensive analysis of the emerging carcinogens and their various sources from process industries, especially in the form of organic waste and their removal by electrocoagulation and its coupled techniques. The paper also aims to ascertain why the electrocoagulation technique may be a better alternative compared with other methods for the removal of carcinogens in organic wastewater, an analysis which has not been explored before. [Display omitted] • Types & categories of water pollution are clearly discussed. • Effects of organic wastes and industries producing wastes are highlighted. • Harmful carcinogens present in the industrial waste water are listed. • Application of electrocoagulation in different process industries are investigated. • Removal of metals from waste water using electrocoagulation are discoursed. [ABSTRACT FROM AUTHOR]

The inefficiency of interspecies electron transfer between syntrophic bacteria and methanogens typically restricts the reaction rates and methanogenesis efficiency of anaerobic digestion (AD) of organic waste. Direct interspecies electron transfer (DIET) has been proposed as a pathway that may enhance AD performance by increasing electron transfer efficiency. This paper comprehensively reviews the main principles and mechanisms of DIET between syntrophic bacteria and methanogens in AD, summarizes strategies for the regulation and enhancement of DIET in AD, and discusses the role of DIET in improving AD efficiency. Literature research demonstrate that c-type cytochromes and e-pili are two major functional components for the cell-to-cell electron transfer and the supplementation of ethanol-enriched substrates along with conductive materials have been proven to be efficient for DIET establishment. It is also confirmed that DIET has the great potential for shortening the start-up period, promoting organic degradation, and enhancing methane production in the AD of organic waste. Furthermore, the main knowledge gaps in the profound understanding of DIET, including the effect of multimedia environment, the establishment of mathematical model and the realization of engineering application, are identified, and the future perspectives are proposed for DIET applications in the AD of organic waste. This paper thus highlights important references and directions that will support research to enhance the DIET pathway and therefore the AD of organic waste. [Display omitted] • Principles of direct interspecies electron transfer (DIET) were overviewed. • Regulation and achievements of DIET in anaerobic digestion (AD) were discussed. • Main knowledge gaps of DIET in AD were identified. • Importance references and directions for improving AD via DIET were provided. [ABSTRACT FROM AUTHOR]

Organic wastes represent an increasing pollution problem due to the exponential growth of their presence in the waste stream. Among these, waste flour cannot be easily reused by transforming it into high-value-added products. Another major problem is represented by epoxy-based thermosets, which have wide use but also poor recyclability. The object of the present paper is, therefore, to analyze both of these problems and come up with innovative solutions. Indeed, we propose a completely new approach, aimed at reusing the organic waste flour, by converting it into high-value epoxy-based thermosets that could be fully recycled into a reusable plastic matrix when added to the waste epoxy-based thermosets. Throughout the research activity, the organic waste was transformed into an epoxidized prepolymer, which was then mixed with a bio-based monomer cured with a cleavable ammine. The latter reactant was based on Recyclamine™ by Connora Technologies, and in this paper, we demonstrate that this original approach could work with the synthetized epoxy prepolymers derived from the waste flour. The cured epoxies were fully characterized in terms of their thermal, rheological, and flexural properties. The results obtained showed optimal recyclability of the new resin developed. [ABSTRACT FROM AUTHOR]

In this study, 12 organic waste materials were subjected to TG/DTG thermogravimetric analysis and DSC calorimetric analysis. These analyses provided basic information about thermochemical transformations and degradation rates during organic waste pyrolysis. Organic waste materials were divided into six basic groups as follows: paper, cardboard, textiles, plastics, hygiene waste, and biodegradable waste. For each group, two waste materials were selected to be studied. Research materials were (i) paper (receipts, cotton wool); (ii) cardboard (cardboard, egg carton); (iii) textiles (cotton, leather); (iv) plastics (polyethylene (PET), polyurethane (PU)); (v) hygiene waste (diapers, leno); and (vi) biodegradable waste (chicken meat, potato peel). Waste materials were chosen to represent the most abundant waste that can be found in the municipal solid waste stream. Based on TG results, kinetic parameters according to the Coats–Redfern method were determined. The pyrolysis activation energy was the highest for cotton, 134.5 kJ × (mol∙K)−1, and the lowest for leather, 25.2 kJ × (mol∙K)−1. The DSC analysis showed that a number of transformations occurred during pyrolysis for each material. For each transformation, the normalized energy required for transformation, or released during transformation, was determined, and then summarized to present the energy balance. The study found that the energy balance was negative for only three waste materials—PET (−220.1 J × g−1), leather (−66.8 J × g−1), and chicken meat (−130.3 J × g−1)—whereas the highest positive balance value was found for potato peelings (367.8 J × g−1). The obtained results may be applied for the modelling of energy and mass balance of municipal solid waste pyrolysis. [ABSTRACT FROM AUTHOR]

Urban waste can be valorized within a biorefinery approach, producing platform chemicals, biopolymers and energy. In this framework, hydrodynamic cavitation (HC) is a promising pre-treatment for improving biodegradability due to its high effectiveness and low cost. This paper deals with the effect of HC pre-treatment on the acidogenic co-fermentation process of thickened sewage sludge from a WWTP and seasonal vegetable waste from a wholesale market. Specifically, HC was assessed by testing two sets of parameters (i.e., treatment time of 30 and 50 min; vacuum pressure 1.4 and 2.0 bar; applied power 8 and 17 kW) to determine its effectiveness as a pre-treatment of the mixture. The highest increase in sCOD (+83%) and VFAs (from 1.93 to 17.29 gCOD VFA L−1) was gained after 50 min of cavitation. Fermentations were conducted with not cavitated and cavitated mixtures at 37 °C on 4 L reactors in batch mode, then switched to semi-continuous with OLR of 8 kg TVS m-3 d−1 and HRT of 5–6.6 d. Good VFAs concentrations (12.94–18.27 gCOD VFA L−1) and yields (0.44–0.53 gCOD VFA g VS(0) −1) were obtained, which could be enhanced by pre-treatment optimization and pH control. The organic acid rich broth obtained was then assessed as a substrate for PHAs storage by C. necator. It yielded 0.37 g g−1 of polyhydroxybutyrate, such biopolymer resulted to have analogous physicochemical characteristics of commercial equivalent. The only generated side-stream would be the solid-rich fraction of the fermented effluent, which valorization was assessed through BMP tests, showing a higher SGP of 0.42 Nm3 kgTVS−1 for the cavitated. [Display omitted] • A mixture of sewage sludge and vegetable waste was pre-treated with cavitation. • Cavitation pre-treatment raised the VFAs content of the mixture by nine folds. • Cavitation-fermentation derived broth resulted performant for PHAs production. • Cavitation raised the SGP of the solid-rich fraction of the fermented broth. [ABSTRACT FROM AUTHOR]

Increasing energy demands and environmental issues have stressed the importance of sustainable methods of energy production. Anaerobic digestion (AD) of the biodegradable waste, i.e., agricultural residues, organic fraction of municipal solid waste (OFMSW), sewage sludge, etc., results in the production of biogas, which is a sustainable and cost feasible technique that reduces the dependence on fossil fuels and also overcomes the problems associated with biomass waste management. To solubilize the organic matter and enhance the susceptibility of hardly biodegradable fraction (i.e., lignocellulosic) for hydrolysis and increase methane production, several pretreatments, including physical, chemical, biological, and hybrid methods have been studied. However, these pretreatment methods under specific operating conditions result in the formation of recalcitrant compounds, such as sugars (xylose, Xylo-oligomers), organic acids (acetic, formic, levulinic acids), and lignin derivatives (poly and mono-phenolic compounds), causing significant inhibitory effects on anaerobic digestion. During the scaling up of these techniques from laboratory to industrial level, the focus on managing inhibitory compounds formed during pretreatment is envisaged to increase because of the need to use recalcitrant feedstocks in anaerobic digestion to increase biogas productivity. Therefore, it is crucial to understand the production mechanism of inhibitory compounds during pretreatment and work out the possible detoxification methods to improve anaerobic digestion. This paper critically reviews the earlier works based on the formation of recalcitrant compounds during feedstocks pretreatment under variable conditions, and their detrimental effects on process performance. The technologies to mitigate recalcitrant toxicity are also comprehensively discussed. [Display omitted] • Recalcitrant are classified into furan derivatives, phenolics compounds and weak organic acids. • Pretreatment method, type, temperature and duration affects the rate of recalcitrant formation. • High temperature pretreatment (>160 °C) alone or in conjugation with highly acidic or alkali pretreatment produced recalcitrant. • Recalcitrant toxicity resulted in reduced biogas yield with longer lag phase in AD process. • Biological detoxification, activated carbon adsorption, ion exchange, and calcium-oxide methods shows promising results [ABSTRACT FROM AUTHOR]

This paper demonstrated the growth ability of twelve algae-microbial consortia (AC) isolated from organic wastes when a pig slurry-derived wastewater (NFP) was used as growth substrate in autotrophic cultivation. Nutrient recovery, biochemical composition, fatty acid and amino acid profiles of algae consortia were evaluated and compared. Three algae-microbial consortia, i.e., a Chlorella-dominated consortium (AC_1), a Tetradesmus and Synechocystis co-dominated consortium (AC_10), and a Chlorella and Tetradesmus co-dominated consortium (AC_12) were found to have the best growth rates (µ of 0.55 ± 0.04, 0.52 ± 0.06, and 0.58 ± 0.03 d−1, respectively), which made them good candidates for further applications. The ACs showed high carbohydrates and lipid contents but low contents of both proteins and essential amino acids, probably because of the low N concentration of NFP. AC_1 and AC_12 showed optimal ω6:ω3 ratios of 3.1 and 3.6, which make them interesting from a nutritional point of view. [ABSTRACT FROM AUTHOR]

With the implementation of new policies supporting renewable natural gas production from organic wastes, Canada began replacing traditional disposal methods with highly integrated biogas production strategies. Herein, data from published papers, Canadian Biogas Association, Canada's national statistical agency, and energy companies' websites were gathered to gain insight into the current status of anaerobic digestion plants in recovering energy and resource from organic wastes. The availability of materials prepared for recycling by companies and local waste management organizations and existing infrastructures for municipal solid waste management were examined. Governmental incentives and discouragements in Canada and world anaerobic digestion leaders regarding organic fraction municipal solid waste management were comprehensively reviewed to identify the opportunities for developing large-scale anaerobic digestion in Canada. A range of anaerobic digestion facilities, including water resource recovery facilities, standalone digesters, and on-farm digesters throughout Ontario, were compared in terms of digestion type, digester volume, feedstock (s), and electricity capacity to better understand the current role of biogas plants in this province. Finally, technology perspectives, solutions, and roadmaps were discussed to shape the future in terms of organic fraction municipal solid waste management. The findings suggested that the biogas industry growth in Canada relies on provincial energy and waste management policies, advanced technologies for diverting organic waste from landfills, improving biogas yield using existing pretreatment methods, and educating farmers regarding digester operations. [ABSTRACT FROM AUTHOR]

Over the coming years, the world is projected to witness an upsurge in "drop-in" aviation biofuel production as part of the renewable energy and bioeconomy developments. This paper presents a comprehensive review of the current status of biojet fuel development and uptake in global commercial aviation industry, including state-of-the-art certified technologies (i.e. Fischer-Tropsch (FT); hydroprocessed esters and fatty acids (HEFA); alcohol-to-jet (ATJ); and hydroprocessing of fermented sugars (HFS)); potential feedstock that can be deployed; a comparison of techno-economic and environmental performances of biojet fuel production routes; airlines' commitment in promoting higher biofuel uptake; and global initiatives and policies. This review shows that the HEFA route using oil-based crops is best performing in terms of lowest production cost and greenhouse gas emissions, however it is in competition with the existing road transport biofuel market. Lignocellulosic biomass and waste feedstock should be promoted in view of replacing food/feed crops which have high indirect land use change emissions. Therefore, further improvement should be focused on FT, ATJ and HFS routes to enhance the cost effectiveness of biojet fuel production and promote commercialisation of these technologies. The selection of feedstock and technologies for SAF production should be justified based on production cost and environmental footprint, while avoiding competition with the existing road transport biofuel market. The shortcomings in the SAF policies such as blending mandate and multiplier in RED II should be addressed to reduce the negative impacts of feedstock competition between the road and aviation biofuel sectors and to meet the decarbonisation targets. • Waste and residue feedstock should be deployed for biojet fuel production. • Non-oil based routes require further improvement on cost competitiveness. • Imposing a blending mandate is more effective than voluntary approach. • Multi-stakeholder collaboration promotes uptake of sustainable aviation fuel. [ABSTRACT FROM AUTHOR]

The aim of this paper was to deepen the knowledge of anaerobic co-digestion of lignocellulosic residues and evaluate the role of soluble organic matter during co-digestion. Buckwheat milling residue (buckwheat hull) was co-digested with different organic wastes to evaluate the effect of co-digestion on biomethane yield, process stability, and their relationship with soluble organic matter. Results showed that co-digestion increased the biomethane yields of buckwheat hull and the best result was achieved from the co-digestion with slaughterhouse wastes (+254% of cumulative biomethane production). Kinetic analysis showed that fruit wastes and brewery trub affected positively anaerobic digestion of lignocellulosic residues, enhancing biomethane potential (+84% and +166%, respectively) and reducing lag phase duration. A positive correlation was found between the soluble organic matter and the biomethane yields during co-digestion experiments. Nevertheless, co-digestion with fruit wastes was affected by an excessive acidification in the early stage of AD (pH 5.7) caused by the rapid conversion of sugars into volatile fatty acids (7 g L-1 at day 15). Although all the digestates showed high concentrations of plant nutrients (the average content of total N was 7.8% dry weight), they were also characterized by residual phytotoxicity (germination index was always 0.0%). results. Increasing the amount of easy biodegradable organic matter during lignocellulosic residues treatment should be the main goal when selecting co-digestion substrates. Chemical composition of co-digestion substrates should be carefully considered, with particular regard to soluble organic matter, to ensure the optimal development of anaerobic digestion with lignocellulosic residues. [Display omitted] • Different co-digestion substrates were tested for lignocellulosic residue digestion. • Soluble organic matter concentration and composition play a key role in co-digestion. • Increased soluble organic matter enhanced biomethane yields. • Composition of co-digestion substrates affects process stability. • Agroindustrial wastes are ideal codigestion substrates for lignocellulosic residue. [ABSTRACT FROM AUTHOR]

The article aims to present results of research on anaerobic digestion (AD) of waste wafers (WF-control) and co-substrate system–waste wafers and cheese (WFC-control), combined with digested sewage sludge, as inoculum. The purpose of this paper is to confirm the outcome of adding silica/lignin (S/L; 4:1) material, as a microbial carrier, on the process performance and genetic diversity of microbial communities. The experiment was conducted in a laboratory under mesophilic conditions, in a periodical operation mode of bioreactors. Selected physicochemical parameters of the tested carrier, along with the microstructure and thermal stability, were determined. Substrates, batches and fermenting slurries were subjected to standard parameter analysis. As part of the conducted analysis, samples of fermented food were also tested for total bacterial count, dehydrogenase activity. Additionally, DNA extraction and next-generation sequencing (NGS) were carried out. As a result of the conducted study, an increase in the volume of produced biogas was recorded for samples fermented with S/L carrier: in the case of WF + S/L by 18.18% to a cumulative biogas yield of 833.35 m3 Mg−1 VS, and in the case of WFC + S/L by 17.49% to a yield of 950.64 m3 Mg−1 VS. The largest total bacterial count, during the process of dehydrogenase activity, was maintained in the WFC + S/L system. The largest bacterial biodiversity was recorded in samples fermented with the addition of cheese, both in the case of the control variant and in the variant when the carrier was used. In contrast, three phyla of bacteria Firmicutes, Proteobacteria and Actinobacteria predominated in all experimental facilities. [ABSTRACT FROM AUTHOR]

Metal-doped CeO 2 nanomaterials are widely used for the photocatalytic degradation of various organic pollutants, such as organic dyes, phenols, amines, and aromatic nitro compounds, from water. Appropriate oxygen vacancies, surface-active cationic sites, and energy bandgap deviation between doped metals and CeO 2 provide a suitable environment for enhancing photocatalytic activities to degrade organic pollutants. [Display omitted] • Metal doped CeO 2 nanomaterials are studied and discussed. • Photocatalytic degradation properties with characteristic bandgap have been studied. • The synthesis routes and conditions, and annealing temperature of the doping ions, and surface morphology are described. • The future perspective of CeO 2 nanomaterials is presented. The increasing concentration of organic pollutants in water has become challenging and has lethal effects on humans and ecology. Metal-based materials have been used as promising candidates for the degradation of organic pollutants. This review summarizes and studies the recent applications of metal-doped CeO 2 -based nanomaterials for photocatalytic degradation of organic waste in the water. The unique properties of metal-doped CeO 2 , such as its characteristic bandgap, oxygen vacancies, and surface-active cationic sites, have been studied for organic waste degradation. In addition, the properties of the synthesis routes and conditions, reaction temperature, concentration, nature and annealing temperature of the doping ions, and surface morphology are described. Finally, challenges and prospects for the development of doped CeO 2 as a photocatalyst with precise morphology and synthesis routes are discussed. [ABSTRACT FROM AUTHOR]