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Due to their detrimental and persistent impacts on the environment, it is imperative to manage and dispose of hazardous wastes (HW) in a secure manner. This study investigates the combustion characteristics and environmental impacts of using HW as alternative fuels in clinker production. The HW categories analyzed include industrial hazardous waste (IHW), medical hazardous waste (MHW), and household hazardous waste (HHW). Specifically, IHW consists mainly of waste mineral oils, waste organic solvents, organic resin wastes, waste residues, and waste coatings. MHW primarily consists of medical plastic products. HHW mainly includes packaging from waste pharmaceuticals, waste pesticides, disinfectants, and waste paints. Compared to traditional pulverized coal, hazardous waste alternative fuel (HWAF) exhibits a lower fixed carbon content, with its heat generation primarily dependent on volatile substances, and a higher ash content, chemically similar to coal ash. The combustion process of HWAF involves three stages: moisture evaporation (0 °C–150 °C), volatile matter combustion (150°C–400 °C), and fixed carbon combustion (400 °C–550 °C). The primary emissions from this process include CO 2 , CO, trace amounts of SO 2 , NO 2 , H 2 O, and various complex organic compounds such as carboxylic acids, alcohols, ketones, and aldehydes. While HWAF ignites more readily than pulverized coal, it burns more slowly and less completely. The incorporation of combustion by-products into the cement clinker formulation does not interfere with the clinker's hydration processes or reactions. HWAF ensures a reduced heavy metal input rate in the firing system without significantly impacting the heavy metal content in the clinker. Mortar samples produced with this clinker meet the heavy metal leaching standards, affirming the environmental safety of the cement product. Increasing the proportion of HWAF results in a reduction in standard coal consumption and an increase in CO 2 reduction, achieving a maximum coal saving of 3.67 kgce/t.cl and a CO 2 emission reduction of 10.11 kg/t.cl. This study presents a clean production model for the co-processing of HWAF, effectively transforming waste into valuable resources by using hazardous waste materials as alternative fuels. [ABSTRACT FROM AUTHOR]

In this paper, poplar sawdust (PS), walnut shell (WS), sugarcane bagasse (SB), polyethylene (PE), and paper napkin (PN) were selected as typical organic solid waste for the study of steam (co-)gasification coupled with on-line analysis of H 2 -rich syngas. The carbon conversion efficiency of PE is only 10.8% and needs to be improved. The mixture of SB + PE exhibited the most pronounced positive synergies, with H 2 /CO reaching 2.40 without catalyst and the synergistic indices of 0.320, 0.298, and 0.226 for H 2 yield, syngas yield, and H 2 /CO, respectively, and these synergies were evident throughout the entire gasification process. The synergistic mechanism was analyzed through the interphase migration of alkali and alkaline earth metals and the morphological properties of the char. Compared with the co-gasification at 900 °C, the synergistic indices of the SB + PE co-gasification parameters at 800 °C were reduced to different degrees, and even the co-gasification at 700 °C showed a remarkable negative synergism. [Display omitted] • Steam co-gasification of various MSWs was carried out online for H 2 -rich syngas. • Co-gasification of SB + PE showed optimal synergy for both H 2 yield and H 2 /CO. • Synergistic mechanism was discussed in terms of AAEMs migration and char structure. • High temperatures of 800∼900 °C contributed to unleashing synergistic potentials. [ABSTRACT FROM AUTHOR]

Heterostructure photocatalytic materials with a high surface area have garnered significant attention in recent years. In this investigation, we successfully synthesized g-C 3 N 4 /TiO 2 tubes using an enhanced impregnation-calcination method. The photocatalytic efficiency of the composite tubes was evaluated by examining the degradation of tetracycline hydrochloride (TCH) solution, revealing a photocatalytic degradation rate 3.7 times and 8.0 times higher than that of pure TiO 2 and g-C 3 N 4 when subjected to simulated sunlight. The enhanced photocatalytic performance can be ascribed to the expanded specific surface area and enhanced separation rate of photo-generated charge carriers. Density functional theory (DFT) calculations and trapping experiments revealed a possible photogenerated electrons transfer pathway in the degradation process of TCH. The photocatalytic fuel cell (PFC) system composed of the g-C 3 N 4 /TiO 2 tubes demonstrated remarkable performance in the concurrent degradation of TCH and electricity generation when being exposed to light. It achieved a short circuit current density of 26.9 mA/g/cm2 and a power density of 5.51 mW/g/cm2. The present study offers a cost-effective approach for both organic waste treatment and electrical power generation. [ABSTRACT FROM AUTHOR]

• Co-pyrolysis Ea was ∼ 50 % lower than with waste textiles alone. • 3D diffusion explained co-pyrolysis devolatilization stages. • Co-pyrolysis increased hydrocarbon yield, lowered emissions. • Co-pyrolysis enhanced sugar and acid decomposition. • Co-pyrolysis char showed more fatty alkyls and branching. Co-pyrolysis is a promising technology for industrial organic waste to utilize their unique resource and energy properties for efficient conversion into valuable products. This study was the first time to characterize the co-pyrolysis of waste textiles with Ca-rich industrial sludge and Fe-rich industrial sludge on a laboratory-scale fixed bed. The properties, mechanisms, gas, oil and carbon production were investigated as a function of temperature and mixing type. Co-pyrolysis increased the total weight loss from 50.05 % to 69.81 % for Ca-rich industrial sludge mixed with 50 % waste textiles and from 49.13 % to 70.01 % for Fe-rich industrial sludge mixed with 50 % waste textiles. The activation energy of co-pyrolysis was approximately 50 % lower compared to the pyrolysis of waste textiles alone. The optimal reaction model for the different reaction stages for all samples was three diffusion (D3). Co-pyrolysis resulted in lower CO and CO 2 emission temperatures of about 25–110 °C and produced more short-chain organic compounds (C < 10). Co-pyrolysis produced more aldehydes and ketones organics. Moreover, co-pyrolysis char exhibited an elevated level of fatty alkyl side chains and bridge branching, as well as higher degrees of aromatization and stability. This study offers valuable insights into the potential application of pyrolysis for the management of Ca/Fe-rich industrial sludge and waste textiles, thereby serving as a basis for future utilization endeavors. [ABSTRACT FROM AUTHOR]

Plastic waste entering the environment through landfilling or improper disposal poses substantial risks to ecosystems and human health. Photoreforming is emerging as a clean photocatalytic technology that degrades plastic waste to organic compounds while simultaneously producing hydrogen fuel. This study introduces high-pressure torsion (HPT), a severe plastic deformation (SPD) method, as an innovative technique to enhance the photoreforming of polypropylene (PP) plastic mixed with a brookite TiO 2 photocatalyst. Hydrogen production systematically increases with the number of HPT turns, accompanied by the formation of valuable small organic molecules. The enhancement in photocatalytic activity is attributed to strain-induced defect formation in both catalysts and plastics, as well as the creation of catalyst/plastic interphases that enhance charge carrier transport between inorganic and organic phases. These findings reveal a new functional application for SPD in energy conversion and sustainability. • High-pressure torsion (HPT) is used for the photodegradation of polypropylene plastic wastes. • Brookite TiO 2 is employed as a photocatalyst for the photodegradation. • Hydrogen production from plastic degradation increased with HPT processing. • This increase is due to strain-induced defects and catalyst/plastic interphase formation. [ABSTRACT FROM AUTHOR]

Starch wastes are organic pollutants that have a negative impact on the environment. Bacillus cereus BX16 , a newly isolated strain with the capacity to exclusively digest starch, was separated and purified using food waste (FW). The efficiency of starch breakdown by Bacillus cereus BX16 was greatly influenced by operational parameters, such as organic load rates (OLRs), pH and temperature. According to the findings, Bacillus cereus BX16 degraded more effectively at the starting starch concentration of 20 g/L. Further optimization resulted in approximately 90% and 99% removal of soluble chemical oxygen demand (SCOD) and polysaccharides, over a wide range of settings (pH 5.0–9.0, 25 °C to 37 °C). In addition, when starch was effectively degraded, 90% of the residual SCOD (<5000 mg/L) consisted mainly of proteins and volatile fatty acids (VFAs). In contrast, in the absence of active Bacillus cereus BX16 , the residual polysaccharide and glucose concentration jumped to 20,000 mg/L. Ultimately, the unique biological method of treating starch waste with Bacillus cereus BX16 also proves the effectiveness of microbial treatment. [Display omitted] • The new Bacillus cereus used for starch degradation was isolated from food waste. • The main metabolite of Bacillus cereus was VFAs. • The operating conditions were starch 20 g/L, pH=9.0, temperature 37 ℃ for 9 d. • The removal rates of SCOD and polysaccharide were 90 % and 99 % respectively. • The biomass degradation ability of Bacillus cereus was stable and efficient. [ABSTRACT FROM AUTHOR]

Hydrogen-rich gas, characterized by high yield and purity, can be effectively generated through the steam gasification of sewage sludge (SS), offering substantial benefits for organic solid waste treatment and resource conservation. This study evaluated the gasification performance in a horizontal moving-bed reactor employing a wet-mixed CaO-red mud (CaO-RM) composite catalyst. The effects of CaO loading rate (CaO/RM), catalyst-to-SS ratio (CaO-RM/SS), and reaction temperature on the syngas yield, lower heating value (LHV), carbon conversion ratio, H 2 to CO (H 2 /CO) ratio, and H 2 yield were investigated. Results indicated that red mud loaded with a calcium-based catalyst significantly enhanced syngas production, particularly for hydrogen generation, during SS gasification. A maximum hydrogen molar fraction of 50.84% and a yield of 7.07 mol/kg were achieved with a CaO/RM of 40% and a CaO-RM/SS of 30% at 750 °C. With the reaction temperature increase from 700 to 900 °C, the catalytic performance for secondary tar cracking and steam reforming was further enhanced. The total syngas yield, H 2 yield, hydrogen molar fraction, LHV of syngas, and carbon conversion rate peaked at 0.79 m³/kg, 19.30 mol/kg, 54.41%, 10,249.48 kJ/kg, and 65.67%, respectively, at 900 °C. • Study boosts energy conversion of sewage sludge with new CaO-RM composite catalyst. • Examines effects of CaO loading rate, catalyst/SS ratio, temperature on gasification. • Prepared CaO-RM catalyst greatly increase syngas, especially hydrogen production. • Temperature rise from 700 to 900 °C boosts catalytic tar cracking and reforming. [ABSTRACT FROM AUTHOR]

[Display omitted] • Large datasets of U and UP are constructed with 1526 and 743 fuel samples. • The effect of C, H, and O atomic ratios on HHV is investigated by ternary plots. • HHV of any type of waste and fuel is estimated by artificial neural networks. • Hyperparameter optimization is carried out to obtain best performing ANN models. • Ultimate analysis data is observed to be sufficient for HHV estimation of fuels. Higher heating value (HHV) is one of the most important parameters in determining the quality of the fuels. In this study, comparatively large datasets of ultimate and proximate analysis are constructed to be used in HHV estimation of several classes of fuels, including char & fossil fuels, agricultural wastes, manure (chicken, cow, horse, sheep, llama, and pig), sludge (like paper, paper-mil, sewage, and pulp), micro/macro-algae's, wastes (RDF and MSW), treated woods, untreated woods, and others (non-fossil pyrolysis oils) between the HHV range of 4.22–55.55 MJ/kg. The relationships of carbon, hydrogen, and oxygen atomic ratios for fuel classes are illustrated by using ternary plots, and the effects of elemental composition on HHV was analyzed with the extensive dataset. Then, the ultimate (U) and ultimate & proximate (UP) datasets were utilized separately to estimate the HHV by using artificial neural networks (ANN). Hyperparameter optimization was carried out and the best performing ANNs were determined for each dataset, which yielded R2 values of 0.9719 and 0.9715, respectively. The results indicated that while ANNs trained by both datasets perform remarkably well, utilization of U dataset is sufficient for HHV estimation. Finally, the best performing ANN models for both U and UP datasets are given in a directly utilizable format enabling the accurate estimation of HHV of any fuel for optimization of fuel processing and waste management operations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The biological CO production in the compost pile was carried out by bacteria. • Bacteria isolated from compost produced CO with concentration > 1000 ppm. • The most common genus in compost was Bacillus with four representatives. • B. paralicheniformis and B. licheniformis produced the highest concentrations of CO. • High CO concentrations were accompanied by low O 2 (<6%) and high CO 2 levels (>8%) Carbon monoxide (CO) formation has been observed during composting of various fractions of organic waste. It was reported that this production can be biotic, associated with the activity of microorganisms. However, there are no sources considering the microbial communities producing CO production in compost. This preliminary research aimed to isolate and identify microorganisms potentially responsible for the CO production in compost collected from two areas of the biowaste pile: with low (118 ppm) and high CO concentration (785 ppm). Study proved that all isolates were bacterial strains with the majority of rod-shaped Gram-positive bacteria. Both places can be inhabited by the same bacterial strains, e.g. Bacillus licheniformis and Paenibacillus lactis. The most common were Bacillus (B. licheniformis, B. haynesii, B. paralicheniformis, and B. thermolactis). After incubation of isolates in sealed bioreactors for 4 days, the highest CO levels in the headspace were recorded for B. paralicheniformis (>1000 ppm), B. licheniformis (>800 ppm), and G. thermodenitrificans (∼600 ppm). High CO concentrations were accompanied by low O 2 (<6%) and high CO 2 levels (>8%). It is recommended to analyze the expression of the gene encoding CODH to confirm or exclude the ability of the identified strains to convert CO 2 to CO. [ABSTRACT FROM AUTHOR]

• 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]

Due to the increased demand for energy resources and the continuous increase in population, the use of RES from biomass and waste is becoming increasingly popular. The work analyzed existing approaches to solving global environmental and social problems through the use of landfill gas generated at municipal solid waste (SMW) landfills, as well as further reforming of biogas into biohydrogen. Waste monitoring was also carried out on the territory of LR and St. Petersburg. It was found that more than 12 million m3 of SMW of hazard classes 1–5 are formed annually in the region. It has been shown that the majority of waste is biodegradable organic matter (about 20%). To increase the biogas potential of SMW landfills during degassing and create additional economic benefits, a system for blowing and irrigation of landfill masses with the addition of a substrate from residual biomass of Chlorella microalgae was proposed. It is proposed to improve the scheme for sorting and using organic waste through selective collection and separation from the total mass of waste at the site of generation. A waste flow diagram has been developed taking into account the material balance of SMW in LR and St. Petersburg. Using this scheme will avoid contamination of other recycled SMW components. In addition, the work proposes a scheme for the further use of biomethane obtained at SMW landfills. Using reforming, it is proposed to purify the resulting gas to biohydrogen. The production of biohydrogen from biogas is cost-effective and can become an alternative to petroleum products. This technology could become a key element in the production of environmentally friendly fuels and the reduction of harmful emissions into the atmosphere. [ABSTRACT FROM AUTHOR]

Anaerobic fermentation has attracted wide attention to effectively reduce carbon footprint and alleviate potential energy shortages, which is being regarded as a sustainable and promising technology to obtain high biohydrogen production from widespread organic wastes. However, biohydrogen commercial uptake is now dominantly inhibited by the low hydrogen yield and process instability. In this work, Al 2 O 3 /BaFe 2 O 4 nanoparticles (NPs) are successfully applied to anaerobic fermentation for investigating their effects on hydrogen yield, activity of bacteria and microbial community structure. The benefits of Al 2 O 3 /BaFe 2 O 4 NPs with respect to microbial metabolism, reactivity of enzymes and process optimization are systematically researched through batch experiments. In addition, various characterizations are used to verify the physical and chemical properties of Al 2 O 3 /BaFe 2 O 4 NPs. The results show that the activity of hydrogenases and microbe metabolism can be significantly inhibited by excess addition of Al 2 O 3 /BaFe 2 O 4 NPs (150 mg/L and 200 mg/L) while the optimum addition 100 mg/L of Al 2 O 3 /BaFe 2 O 4 NPs can boost the biohydrogen yield by 49% via facilitating microorganism growth and enhancing key enzymatic activities, which indicate that the Al 2 O 3 /BaFe 2 O 4 NPs display a beneficial influence on electron transfer efficiency and process stability. The existence of Fe3+, Al3+and Ba2+ derived from the corrosion of Al 2 O 3 /BaFe 2 O 4 NPs by organic acids synergistically improve the microbial transmembrane transportation and substrate utilization, which contribute to higher conversion rate of glucose into acetate, butyrate and H 2. Meanwhile, the complementary functions of Fe3+ and Al3+ can powerfully shorten the lag phase and promote the glycolysis, which finally accelerate the dark fermentation process. Compared with the control group, Clostridium _ sensu _ stricto _1 is selectively enriched by the addition of Al 2 O 3 /BaFe 2 O 4 NPs, which keep heavily involved in the synthesis of H 2. On balance, this study provides an effective strategy to enhance hydrogen productivity and maintain process stability, which offer the valuable information for the sustainable utilization of sewage sludge. [Display omitted] • Al 2 O 3 /BaFe 2 O 4 NPs are synthesized to enhance H 2 production. • Al 2 O 3 /BaFe 2 O 4 NPs show positive effects on activity of H 2 -producing bacteria. • The addition of Al 2 O 3 /BaFe 2 O 4 NPs can facilitate H 2 -producing bacteria growth. • Humic acids are reduced by addition of Al 2 O 3 /BaFe 2 O 4 NPs. • Firmicutes and Clostridium_sensu_stricto_ 1 are selectively enriched by Al 2 O 3 /BaFe 2 O 4 NPs. [ABSTRACT FROM AUTHOR]

• The black soldier fly links sustainable protein production and waste valorisation. • Larval diet impacts development time, lifespan, adult body size and egg production. • Spent Brewer's grains resulted in the best performing flies. • Even flies on low-nutritious larval diets produced fertile eggs. The interest in mass-rearing black soldier fly (Hermetia illucens) larvae for food and feed is rapidly increasing. This is partly sparked by the ability of the larvae to efficiently valorise a wide range of organic waste and by-products. Primarily, research has focused on the larval stage, hence underprioritizing aspects of the adult biology, and knowledge on reproduction-related traits such as egg production is needed. We investigated the impact of different organic waste and by-products as larval diets on various life-history traits of adult black soldier flies in a large-scale experimental setup. We reared larvae on four different diets: spent Brewer's grain, ground carrots, Gainesville diet, and ground oranges. Traits assessed were development time to pupa and adult life-stages, adult body mass, female lifespan, egg production, and egg hatch. Larval diet significantly impacted development time to pupa and adult, lifespan, body size, and egg production. In general, flies reared on Brewer's grain developed up to 4.7 d faster, lived up to 2.3 d longer, and produced up to 57% more eggs compared to flies reared on oranges on which they performed worst for these traits. There was no effect of diet type on egg hatch, suggesting that low-nutritious diets, i.e. carrots and oranges, do not reduce the quality but merely the quantity of eggs. Our results demonstrate the importance of larval diet on reproductive output and other adult traits, all important for an efficient valorisation of organic waste and by-products, which is important for a sustainable insect-based food and feed production. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sustainability assessment of SCCA produced from bio-wastes has been performed. • CAFIPLA reduces the environmental impact and social risk of the benchmark technology. • The plant is profitable as long as the product is sold above 0.49 €/kg. Bio-based products are a fast-growing market due to increasing consumer consciousness for sustainability. Although this is per se a positive trend, it leads to a higher demand for organic feedstocks which normally comes from primary agricultural sources and can lead to undesired deforestation or other land use changes to farmland. At the same time, Europe is facing another challenge related with the treatment of organic wastes. In this context, the project CAFIPLA developed an integrated process to convert heterogeneous organic materials to building blocks for the bio-based economy. This study performs a life cycle sustainability assessment (life cycle assessment, life cycle costing and social life cycle assessment) of the production of short chain carboxylic acids (SCCA) employing municipal bio-wastes as a feedstock. In addition to a hot-spot identification to detect the main sources of impact, a comparison of the novel technology with the current benchmark is carried out applying a cradle-to-gate approach and using 1 kg of SCCA as a functional unit. Results show the great performance of CAFIPLA in all the environmental categories analysed. Furthermore, the profitability of the plant is also verified, reaching a payback period below 6 years as long as the product is sold above 0.49 €/kg. Finally, the potential social risk associated to the supply chain is also improved with CAFIPLA technology. [ABSTRACT FROM AUTHOR]

Ca–Fe oxygen carrier (OC) is an effective material with high selectivity on H 2 and CO to aid to the gasification of solid fuel materials such as organic solid waste or biomass in chemical-looping gasification (CLG). However, the reaction mechanism of raw materials with high volatiles such as cellulose remains unclear. Kinetics analysis is considered as the efficient method to investigate the reaction mode and mechanism. In this study, isothermal method was conducted and the tristate intermedia products were used as substrates to reveal the kinetics characteristic of cellulose conversion process in CLG. The results demonstrated that the reduction process of Ca–Fe OC could be divided into three stages, and the activation energies were 40.40 kJ/mol, 91.28 kJ/mol and 165.33 kJ/mol, respectively; this indicates that the lattice oxygen could be transferred easily in the first stage, but much more difficult in the later two stages. The weak oxidizing molecules such as CO 2 could re-oxide the reduced OC quickly and the activation energy was 27.83 kJ/mol. The mechanism model on kinetic of tar cracking was similar to the reaction between H 2 and OC, and the activation energy was 82.27 kJ/mol. The decomposition of char was recognized as the stochastic nuclear shrinkage process with an activation energy of 52.22 kJ/mol. [Display omitted] • Kinetics of tristate product of cellulose chemical looping gasification is analyzed. • The reduction of Ca–Fe oxygen carrier can be divided as three stages. • Kinetically, Ca–Fe oxygen carrier can be re-oxidized by CO 2 easily. • The mechanism model of tar cracking is similar to the H 2 oxidized. • The decomposition of char is recognized as the process of stochastic nuclear shrinkage. [ABSTRACT FROM AUTHOR]

• Community composting was systematically studied in terms of atmospheric emissions. • Ammonia, methane, nitrous oxide, VOC and odours were measured in several sites. • Community compost presents a good quality, especially in terms of stability. • VOC families were diverse, although terpenes were the predominant compounds. • The age of the material and turning dramatically affects gaseous emissions. Composting has demonstrated to be an effective and sustainable technology to valorise organic waste in the framework of circular economy, especially for biowaste. Composting can be performed in various technological options, from full-scale plants to community or even individual composters. However, there is scarce scientific information about the potential impact of community composting referred to gaseous emissions. This work examines the emissions of methane and nitrous oxide as main GHG, ammonia, VOC and odours from different active community composting sites placed in Spain, treating kitchen, leftovers and household biowaste. Expectedly, the gaseous emissions have an evident relation with the composting progress, represented mainly by its decrease as temperature or biological activity decreases. GHG and odour emission rates ranged from 5.3 to 815.2 mg CO 2eq d-1 kg-1VS and from 69.8 to 1088.5 ou d-1 kg-1VS, respectively, generally being lower than those find in open-air full-scale composting. VOC characterization from the community composting gaseous emissions showed a higher VOC families' distribution in the emissions from initial composting phases, even though terpenes such as limonene, α-pinene and β-pinene were the most abundant VOC along the composting process occurring in the different sites studied. The results presented in this study can be the basis to evaluate systematically and scientifically the numerous current projects for a worldwide community composting implementation in decentralised biowaste management schemes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning is usually used for compost maturity and environmental pollutants. • Artificial neural network is the most widely used in simulating composting process. • Ensemble models prioritize composting variables effectively. • Genetic algorithm is used to optimize compost product quality. • Further research on interpretable algorithms and algorithms combination is needed. Aerobic composting stands as a widely-adopted method for treating organic solid waste (OSW), simultaneously producing organic fertilizers and soil amendments. This biologically-driven biochemical reaction process, however, presents challenges due to its complex non-linear metabolism and the heterogeneous nature of the solid medium. These characteristics inherently limit the simulation accuracy and efficiency optimization in aerobic composting. Recently, significant efforts have been made to simulate and control composting process parameters, as well as predicting and optimizing composting product quality. Notably, the integration of machine learning (ML) in aerobic composting of organic waste has garnered considerable attention for its applicability and predictive capability in exploring the complex non-linear relationships of organic waste composting parameters. Despite numerous studies on ML applications in OSW composting, a systematic review of research findings in this field is lacking. This study offers a systematic overview of the application level, current status, and versatility of ML in OSW composting. It spans various aspects, such as compost maturity, environmental pollutants, nutrients, moisture, heat loss, and microbial metabolism. The survey reveals that ML-intervention predominantly focuses on compost maturity and environmental pollutants, followed by nutrients, moisture, heat loss, and microbial activity. The most commonly employed predictive models and optimization algorithms are artificial neural networks (47%) and genetic algorithms (10%). These demonstrate high prediction accuracy and maximize composting efficiency in the simulation and prediction of organic waste composting, alongside regulation of key parameters. Deep neural networks and ensemble learning models prove effective in achieving superior predictive performance by selecting feature variables in compost maturity and pollutant residue prediction of organic waste composting in a simpler and more objective manner. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar amendment to the digestate-based bioponics improved plant yield. • Biochar adsorbed heavy metals and decreased their bioaccumulation in plants. • Noncancer and cancer risks were found from ingestion of the plants. • Biochar enhanced microbial communities, aiding metal stabilization in bioponics. • Biochar promoted genera in sludge and plant roots for efficient P and N recovery. Bioponics is a nutrient-recovery technology that transforms nutrient-rich organic waste into plant biomass/bioproducts. Integrating biochar with digestate from anaerobic wastewater treatment process can improve resource recovery while mitigating heavy metal contamination. The overarching goal of this study was to investigate the application of biochar in digestate-based bioponics, focusing on its efficacy in nutrient recovery and heavy metal removal, while also exploring the microbial community dynamics. In this study, biochar was applied at 50 % w/w with 500 g dry weight of digestate during two 28-day crop cycles (uncontrolled pH and pH 5.5) using white stem pak choi (Brassica rapa var. chinensis) as a model crop. The results showed that the digestate provided sufficient phosphorus and nitrogen, supporting plant growth. Biochar amendment improved plant yield and phosphate solubilization and reduced nitrogen loss, especially at the pH 5.5. Furthermore, biochar reduced the heavy metal accumulation in plants, while concentrating these metals in the residual sludge. However, owing to potential non-carcinogenic and carcinogenic health risks, it is still not recommended to directly consume plants cultivated in digestate-based bioponic systems. Additionally, biochar amendment exhibited pronounced impact on the microbial community, promoting microbes responsible for nutrient solubilization and cycling (e.g., Tetrasphaera , Herpetosiphon , Hyphomicrobium , and Pseudorhodoplanes) and heavy metal stabilization (e.g., Leptolinea , Fonticella , Romboutsia , and Desulfurispora) in both the residual sludge and plants. Overall, the addition of biochar enhanced the microbial community and facilitated the metal stabilization and the cycling of nutrients within both residual sludge and root systems, thereby improving the overall efficiency of the bioponics. [ABSTRACT FROM AUTHOR]

[Display omitted] • CaMn 0.5 Fe 0.5 O 3-δ -washed can ensure 61% of the effective gas fuel components. • Nanometer-sized MnO 2 can facilitate the oxygen uncoupling regeneration. • The anti-deposition performance of the oxygen carrier enhanced by washing red mud. • The reacted oxygen carrier exhibits a hollow structure that is easily fluidized. Chemical looping gasification (CLG) is a promising technology that utilizes lattice oxygen for partial oxidation of solid organic waste to produce high-quality syngas. The utilization of low-cost and high-performance oxygen carriers (OCs) is important for the success of this technology. The red mud from aluminum production was mixed with calcium and manganese oxides to prepare CaMn 0.5 Fe 0.5 O 3-δ perovskite OCs. The comparative redox tests were carried out to analyze the reactivity using a thermogravimetric analyzer (TGA). Multiple cycle CLG experiments were conducted on a wet municipal sludge in a lab-scale fluidized bed to produce the hydrogen-rich gas. The results showed that the CaMn 0.5 Fe 0.5 O 3-δ -washed demonstrated higher oxygen transfer capacity and better cycling stability with a maximum weight loss of 7.3096 %. After the 5th cycle in CLG, the syngas obtained using CaMn 0.5 Fe 0.5 O 3-δ -washed maintained a H 2 volume fraction exceeding 40%. However, an increase in CO 2 production was also observed, which could be due to the catalytic effect of MnO in the OC on the steam-reforming reaction. The XRD curves showed that fresh CaMn 0.5 Fe 0.5 O 3-δ -washed exhibited prominent diffraction peaks characteristic of perovskite. It was observed that after undergoing 5 cycles, the presence of iron calcium silicate structures containing Mn became evident due to the attachment of sludge ash, leading to the increased impurities on the surface of OCs with a decrease in the specific surface area. Additionally, some of the reacted OC particles exhibited a hollow structure, facilitating the fluidization. This preliminary study provides the basis for the improvement of the OC performance in sludge gasification. [ABSTRACT FROM AUTHOR]

• Sustainable methane obtained by injection of liquified kitchen and food waste. • Ammonia gas emissions occurred mainly in rapid methane production phase. • Hydrogen sulfide gas emissions occurred in rapid and post-methane production phases. • Organic carbon in leachate decreased as injection round increased. • Salinity decreased during rapid methane production phase but increased thereafter. With continuous advancements in the zero-waste strategy in China, transportation of fresh municipal solid waste to landfills has ceased in most first-tier cities. Consequently, the production of landfill gas has sharply declined because the supply of organic matter has decreased, rendering power generation facilities idle. However, by incorporating liquefied kitchen and food waste (LKFW), sustainable methane production can be achieved while consuming organic wastewater. In this study, LKFW and water (as a control group) were periodically injected into high and low organic wastes, respectively. The biochemical characteristics of the resulting gas and leachate were analyzed. LKFW used in this research generated 19.5–37.6 L of methane per liter in the post-methane production phase, highlighting the effectiveness of LKFW injection in enhancing the methane-producing capacity of the system. The release of H 2 S was prominent during both the rapid and post-methane production phases, whereas that of NH 3 was prominent in the post-methane production phase. As injection continued, the concentrations of chemical oxygen demand, 5-d biological oxygen demand, total organic carbon, ammonia nitrogen, total nitrogen, and oil in the output leachate decreased and eventually reached levels comparable to those in the water injection cases. After nine rounds of injections, the biologically degradable matter of the two LKFW-injected wastes decreased by 8.2 % and 15.1 %, respectively. This study sheds light on determining the organic load, controlling odor, and assessing the biochemical characteristics of leachate during LKFW injection. [ABSTRACT FROM AUTHOR]

• P and S in organic waste were predicted using NIRS with great accuracy. • S prediction showed a direct correlation with sulfur-related functional groups. • P prediction mainly relied on indirect correlation with organic matter bands. • P prediction success was linked to the samples' homogeneity in organic compound. Near-infrared spectroscopy (NIRS) has recently emerged as a valuable tool for monitoring organic waste utilized in anaerobic digestion processes. Over the past decade, NIRS has significantly improved the characterization of organic waste by enabling the prediction of several crucial parameters such as biochemical methane potential, carbohydrate, lipid and nitrogen contents, Chemical Oxygen Demand, and kinetic parameters. This study investigates the application of NIRS for predicting the levels of Sulfur (S) and Phosphorus (P) within organic waste materials. The results for sulfur prediction exhibited a high level of accuracy, yielding an error of 1.21 g/Kg[TS] in an independently validated dataset, coupled with an R-squared value of 0.84. Conversely, the prediction of phosphorus proved to be slightly less successful, showing an error of 1.49 g/Kg[TS] with an R-squared value of 0.70. Furthermore, the disparities in performance seem to stem from the inherent correlation between the spectral data and the sulfur or phosphorus contents. Significantly, a variable selection technique known as CovSel was employed, shedding light on the differing approaches used for sulfur and phosphorus predictions. In the case of sulfur, the prediction was achieved through a direct correlation with wavelengths associated with sulfur-related functional groups (such as R − S(=O) 2 − OH, -SH, and R-S-S-R) present in the NIR spectra. In contrast, phosphorus prediction relied on an indirect correlation with absorption bands related to organic matter (including CH, CH 2 , CH 3 , –CHO, R-OH, C = O, –CO 2 H, and CONH). [ABSTRACT FROM AUTHOR]

• Entotechnologies involve insects to upcycle organic waste. • Frass is an animal manure produced by insects. • 2–4 tonnes of frass are co-generated for each tonne of edible insect produced. • Frass has fertilizing, plant protection and soil health promoting properties. • Frass regulation is developing in Canada, USA and Europe. A range of issues related to sustainability in the agrifood industry have spurred interest in mass production of insects as human food and animal feed alternatives. This rapidly evolving sector addresses several challenges, including the management of food waste or agrifood by-products and the production of alternative animal proteins demonstrating low environmental impacts that improve sector circularity. The mass production of insects on agrifood processing wastes or by-products represents an opportunity to address these challenges. While the production of insects offers prospects for sustainable protein production, a major side stream is the production of frass or larval excrement including uneaten feed and chitin-rich exuviae (derived from multiple larval moults). The production of each tonne of edible insects generates 2 to 4 tonnes of frass with an interesting potential in agriculture versus traditional organic amendments (compost, manure, biochar). This review aims to demonstrate the characteristics of frass, its common harvest and conditioning methods, its optimal application rates for planting crops, the mechanisms by which it can protect plants against biotic and abiotic stresses and demystify the risks and potential associated with its application in agriculture. The characteristics of frass are compared with those of conventional fertilizers or other. This report also compiles the Canadian, US and European regulatory frameworks as a novel plant fertilizer and aims to pave the way for future research necessary for its valorization in plant production. [ABSTRACT FROM AUTHOR]

• Soil contaminated with high levels of oil sludge can be smoldered. • Petroleum hydrocarbons can be fully eliminated from OSS near or above 500 ℃. • The high-temperature smoldering reduces most nutrients and destroys soil quality. • Adding recovered oil enhances the smoldering intensity and remediation efficiency. There is an urgent need to globally remediate oil sludge-contaminated soil (OSS). Smoldering combustion is a new low-energy approach for the treatment of organic waste. Therefore, the feasibility of smoldering combustion for the treatment of OSS was investigated in this study using a series of laboratory-scale experiments. The effective remediation of OSS was found to be achievable when the mass ratio of oil sludge in the sample reached 1/12 and above. Experimental results showed that smoldering at peak temperatures above 500 °C was found to completely remove petroleum hydrocarbons from the samples. The mass ratio of oil sludge in the sample had little effect on the distribution of the major elements (Si, Al, and Ca) in the smoldering products, and most of the minerals in the oil sludge adhered to the surface of the soil particles after smoldering. The smoldering heating environment is detrimental to the reusability of the soil, increases soil pH and available phosphorus content, and decreases organic carbon and total nitrogen content. Moreover, the influence of the airflow rate and material height on smoldering characteristics was investigated. Matching the appropriate airflow rate can help maintain optimal smoldering conditions, and smoldering remains stable with increasing material height. The addition of recovered oil to a sample with a low mass ratio of oil sludge can help with smoldering ignition and improve the removal efficiency of petroleum hydrocarbons. This study has confirmed that smoldering can be used to treat OSS within a broad range of oil sludge concentrations without pretreatment. [ABSTRACT FROM AUTHOR]

• Climate change poses a global threat, primarily through the increasing incidence of droughts. • A potential solution to mitigate crop production losses involves enhancing plants' defense mechanisms against arid conditions using biochemical methods. • Plant-derived smoke solutions offer a sustainable agricultural practice that repurposes organic waste, benefiting both agriculture and the environment. • The application of small quantities of smoke solution proved effective in mitigating the adverse impacts of drought stress on grass peas. • These findings suggest that smoke solutions hold promise as a strategy to combat drought stress. Drought stress poses a significant challenge to agricultural productivity as a primary consequence of climate change. This study aimed to investigate the potential of plant-derived smoke solutions as a novel, natural, and environmentally friendly factor for enhancing drought resistance in grass pea (Lathyrus sativus L.). For this, two varieties of grass pea were independently assessed under three different drought stress (control, moderate and severe) after priming with smoke solution. Drought stress was modulated by water deficiency as the last 4 days in moderate and 8 days in severe drought. Grass pea seeds primed with smoke solution derived from poppy (Papaver somniferum L.) at doses of 1 %, 10 % and with distilled water as control. Biometric measurements, chlorophyll pigments, secondary metabolite levels, and biochemical parameters were analyzed in the experiments. The results indicated that grass pea was sensitive to drought, with no discernible differences between the two varieties. The application of smoke solutions resulted in increased fresh and dry weight for plants grown under both control and drought conditions. While 1 % of smoke solution had a notable impact on leaf relative water content (LRWC), 10 % primarily influenced chlorophyll pigments and malondialdehyde (MDA) levels. Additionally, smoke solutions resulted in increased anthocyanin and secondary metabolite levels. These findings suggest that smoke solutions enhanced the defense mechanisms against drought stress in grass pea, but this improvement varies depending on the solution doses. In conclusion, our study demonstrates that poppy derived smoke solutions have the potential to offer a novel and natural approach for enhancing drought resistance in plants. It also encourages new studies to examine the interaction of different smoke solutions and plants against drought stress. [ABSTRACT FROM AUTHOR]

Anaerobic digestion technology has gained significant attention as an organic solid waste treatment method due to its favorable economic and environmental benefits. However, after digestion, the digestate still contains a significant amount of underutilized organic matter. Sustainable management and resource utilization of digestate plays a crucial role in achieving resource circularity and implementing a circular economy. Previous reviews have mainly focused on improving the operational efficiency and stability of anaerobic digestion, with limited exploration of sustainable management and resource utilization of digestate. To address this gap, this review provides a systematic summary of the sustainable management and resource utilization of digestate. First, the basic characteristics of digestate are outlined. Then, based on a visual analysis of literature on digestate management from the past decade, the review highlights the hotspots in sustainable management and circular utilization of digestate. Finally, it summarizes the relevant policies on digestate management in different regions and outlines the challenges in digestate treatment and disposal. The challenges in digestate management remain a significant issue that requires further exploration and solutions. This review aims to promote the standardization of digestate management, provide direction for further in-depth research on digestate, and contribute to the continued development of resource cycling of anaerobic fermentation products. [Display omitted] [ABSTRACT FROM AUTHOR]

In present, activated carbon (AC) pellets that are commonly prepared by petroleum-based binders have been used to control NO x , SO x , and volatile organic compounds (VOCs) emissions in the iron/steel industry. However, the use of petroleum-based binders leads to great challenges toward sustainability and environment. Alternatively, lignin as a natural bio-binder derived from biomass and organic waste can act as a potential additive for preparing AC pellets. Therefore, in this study, pinewood sawdust was initially fractionated into crude cellulose and lignin by organosolv fractionation method at 90–120 °C for 180 min in an acetic acid/formic acid/water mixed solvent of 3/5/2, 3/6/1, and 5/4/1, vol%/vol%/vol%. Afterward, the fractionated crude lignin was used as bio-additive to substitute 50 wt% of petroleum-derived phenol to synthesize phenol-formaldehyde resole resins (PLPF) and compared with those prepared using 100% petroleum-derived phenol resole resins (PF). PLPF and PF resins were further fabricated to AC pellets by thermal treatment/curing at 150 °C and different loadings of resins (i.e., 10–50 wt%), followed by carbonization at 400 and 700 °C. In the fractionation, it was found that temperature played a role in determining the yield and purity of crude cellulose and lignin, while the effect of solvent composition was insignificant. PLPF resins (loading of 50 wt%)-based AC pellets obtained from thermal treatment at 150 °C followed by carbonization at 400 °C showed a relatively higher compressive strength, which meets the national standard and could ensure their uses as an emission control method in the iron/steel industry. Overall, it can be concluded that lignin-derived from woody biomass by organosolv fractionation in acetic acid/formic acid/water mixture is an alternative bio-binder to prepare AC pellets for emission control at high temperatures. [ABSTRACT FROM AUTHOR]

Currently, the volume of waste generation is growing at a high rate. Anaerobic digestion is an effective way to process organic waste to produce biogas. To increase the bioavailability and efficiency of mass transfer between feedstock particles and microorganisms, it is advisable to pretreat organic waste using various methods. One of the most promising and energy-efficient methods for preparing a feedstock for anaerobic bioconversion is its processing in a vortex layer apparatus (VLA). However, there are some limitations in the VLA operation. Therefore, to exclude the stagnant central zone from the volume of the VLA working chamber and increase the magnitude of the magnetic field in the VLA working chamber, a ferromagnetic core in the form of a steel pipe was coaxially mounted. Thus, the purpose of this work is to experimentally study the effect of the ferromagnetic core of the VLA working chamber on the production of biogas during anaerobic bioconversion of a model of organic waste from the agricultural sector. To achieve this goal, an experimental plant was developed and created. The experimental data obtained suggest the high efficiency of pretreatment of the feedstock in VLA with a ferromagnetic core in the working chamber before anaerobic bioconversion. The developed anaerobic bioconversion system made it possible to increase the methane production rate by 287 % at hydraulic retention time (HRT) of 4 days and by 3.5 times at HRT of 2 days compared to the control. At the same time, the methane yield at HRT of 4 days increased by 43 %, and at HRT of 2 days it decreased by 14 %. The hydrogen sulfide content in biogas also increased more than three times, while no hydrogen was detected in the biogas. Thus, pretreatment of the feedstock in VLA with a ferromagnetic core to produce biohythane in a one-stage anaerobic bioconversion system at 55.1 °C is impractical. [ABSTRACT FROM AUTHOR]

Biofuel production, especially biohydrogen, biogas and biohythane production from waste materials is a promising technology. It contributes a unique opportunity for waste minimization, renewable energy generation and recycling of nutrients. In this review, in order to understand the environmental effects of biohydrogen and biogas produced from renewable energy sources using various production technologies, many publications on the environmental effects of biofuels produced from waste materials have been examined. The aim of this review is to present an overview of the state-of-the-art of different wastes to biohydrogen or/and biogas technologies via fermentation from the perspective of life cycle analysis. Firstly, the hydrogen and biogas production pathways and the required process steps are summarized. Then, life cycle analyses (LCA) studies are discussed in terms of their environmental impacts. It is difficult to completely compare these studies with each other due to differences in functional unit, system boundaries, analysis methods, impact categories, and software. However, as a result of the evaluation, fermentation offer benefits such as reduction of CO 2 emission, ozone depletion, human health, ecotoxicity and fossil depletion. Moreover, it is perceived that the integration of biohydrogen production and anaerobic digestion from organic wastes can be an attractive option to produce biohythane that has high heat efficiency and low GHG emissions instead of biohydrogen or biogas production. Energy producing strategies can be rearranged towards life-cycle philosophy helping for dissemination of renewable energy systems usage. • Enhanced biofuel production depends on feedstock as organic wastes to reduce influences on environmental impacts. • Qualitative data and site-specific LCAs are needed. • Differences in modeling and data units forms uncertainty and variability in LCAs. • Governmental strategies can be rearranged towards life-cycle philosophy. • Biohytane production should be evaluated to mitigate environmental impacts. [ABSTRACT FROM AUTHOR]

Biohythane production through anaerobic digestion of organic waste in a single reactor is a potentially more cost-effective process compared to the traditional two-stage scheme. In this work, the production and composition of biohythane obtained from complex organic waste in a semi-continuous thermophilic anaerobic bioreactor was studied with a gradual increase in hydraulic retention time (HRT) from 2 to 5 days and a corresponding decrease in the organic loading rate from 12.27 to 4.8 g VS/(L·d). At low HRT, a significant predominance of hydrogen content in biogas was observed. However, with an increase in HRT to 5 days, the volumetric and specific yield of methane increased. The modified Gompertz model and the first order model showed a high coefficient of determination (R2 = 0.97–1) for the calculated kinetic parameters of hydrogen and methane formation. At all values of HRT, the predominance of the hydrogen-producing genus Thermoanaerobacterium was observed in the microbial community. When HRT was increased to 5 days, representatives of methanogenic archaea of the genera Methanosarcina and Methanosaeta actively developed. The hydrogen and methane content in the final biogas mixture was approximately 37 % and 30 %, respectively. Potential research avenues for improving biohythane production in a single reactor have been considered. [ABSTRACT FROM AUTHOR]

The development of net-zero emission fuels is a priority area of modern research due to the imminent reduction of fossil fuel reserves and environmental problems caused by their combustion. One of the promising fuels is hydrogen, which has a high heat of combustion and is eco-friendly, forms water as the only byproduct. Recently, methods of hydrogen production by microorganisms, which use directly the solar energy or utilize the organic waste during fermentation, have been intensively developed and applied. In this review, the basic principles of the main light-dependent (biophotolysis, photofermentation) and light-independent (dark fermentation and microbial electrolysis) methods of biological hydrogen production are discussed. Particular attention is paid to the advantages and disadvantages of these methods, the possibility of combining them into a single system, as well as various strategies for improving biohydrogen production aimed at transition from laboratory research to full-scale application. [ABSTRACT FROM AUTHOR]

Big Data wave has led to a rapid increase in the amount of data being collected by organizations. While the accuracy and reliability of prediction models are often prioritized, the quality of the collected data is frequently overlooked. Poor data quality can result in the common problem of 'garbage in, garbage out'. Traditional measures of data quality, such as accuracy, consistency, completeness, and timeliness, are no longer adequate in the era of Big Data. Therefore, this paper proposes a taxonomy of data quality dimensions specifically for Big Data, addressing emerging challenges by formulating 20 dimensions and categorizing them into four distinct categories. [ABSTRACT FROM AUTHOR]

• Automated multi-stage method employed to classify urban wastes. • A novel model named GCDN-Net is proposed as the garbage classifier. • Four different types of waste have been classified using the garbage classifier. • Saliency map-based visualization with ScoreCAM is shown as a qualitative evaluation. The escalating waste volume due to urbanization and population growth has underscored the need for advanced waste sorting and recycling methods to ensure sustainable waste management. Deep learning models, adept at image recognition tasks, offer potential solutions for waste sorting applications. These models, trained on extensive waste image datasets, possess the ability to discern unique features of diverse waste types. Automating waste sorting hinges on robust deep learning models capable of accurately categorizing a wide range of waste types. In this study, a multi-stage machine learning approach is proposed to classify different waste categories using the "Garbage In, Garbage Out" (GIGO) dataset of 25,000 images. The novel Garbage Classifier Deep Neural Network (GCDN-Net) is introduced as a comprehensive solution, adept in both single-label and multi-label classification tasks. Single-label classification distinguishes between garbage and non-garbage images, while multi-label classification identifies distinct garbage categories within single or multiple images. The performance of GCDN-Net is rigorously evaluated and compared against state-of-the-art waste classification methods. Results demonstrate GCDN-Net's excellence, achieving 95.77% accuracy, 95.78% precision, 95.77% recall, 95.77% F1-score, and 95.54% specificity when classifying waste images, outperforming existing models in single-label classification. In multi-label classification, GCDN-Net attains an overall Mean Average Precision (mAP) of 0.69 and an F1-score of 75.01%. The reliability of network performance is affirmed through saliency map-based visualization generated by Score-CAM (class activation mapping). In conclusion, deep learning-based models exhibit efficacy in categorizing diverse waste types, paving the way for automated waste sorting and recycling systems that can mitigate costs and processing times. [ABSTRACT FROM AUTHOR]

• Refractory radioactive PFPE were effectively treated by a synergistic effect of MnO 2 and Na 2 CO 3. • F in PFPE lubricants was converted into inorganic fluoride with a conversion efficiency of ∼99%. • MnO 2 provided acid sites and attacked the basic sites in PFPE based on Lewis acid-base concept. • F-containing gas could be oxidized by adsorbed oxygen and then immobilized by a solid absorbent. Perfluoropolyether (PFPE) lubricants are a kind of high-molecular polymer with many excellent properties. However, the use of PFPEs in the nuclear industry can lead to partial decomposition and carrying radionuclides, resulting in a large amount of radioactive waste PFPE lubricants annually. Moreover, radioactive waste PFPE lubricants are difficult to be effectively treated due to their high stability, the risk of possible leakage of radionuclides, and hypertoxic fluorine-containing by-products. In this study, without any precedent, a strategy of MnO 2 -catalyzed decomposition and Na 2 CO 3 -immobilized conversion was proposed for PFPE lubricant decomposition and fluorine immobilization simultaneously based on the Lewis acid-base and oxygen vacancies concept. A high fluorine conversion efficiency of 95.4% was achieved. Meanwhile, the mechanism of decomposition suggested that MnO 2 mainly provided Lewis acid sites and attacked the (basic) fluorine or oxygen atoms in PFPE molecules. The decomposition of PFPE chains was proceed down and volatile fluorine-containing gas was released by partial electron transfer, intramolecular disproportionation reaction, and unzipping fashion. Subsequently, gas by-products could be further oxidized and then immobilized into fluoride salts by carbonate solid absorbents. Overall, this study provides a simple, safe, and potentially practical strategy for the harmless conversion of refractory fluorinated organic wastes, especially perfluoropolymers. [Display omitted] [ABSTRACT FROM AUTHOR]

• Microbial inoculants, (Rhizobium and two strains of AMF), were evaluated for their effectiveness in mitigating metal toxicity and reducing metal uptake in lentil plants. • Sewage sludge-amended soil adversely impacted lentil growth, leading to increased accumulation of heavy metals. • Microbial inoculants enhanced lentil growth and productivity, particularly under heavy metal stress. • Co application of microbial inoculants synergistically reduced heavy metal uptake in roots and shoots of lentil with more efficiency. • The findings suggest microbial inoculants could have practical applications for sustainable agriculture and efficient crop production. Reusing sewage sludge as a mode of nutrients and an organic amendment may be a viable choice for the appropriate treatment of organic waste. This study examined the impact of symbiotic microbes such as Rhizobium and two selected arbuscular mycorrhizal fungi (AMF), Funneliformis caledonius (Nicolson & Gerd.) and Glomus bagyarajii (Mehrotra), on the growth, photosynthetic pigments, biochemical content, microbial population, and heavy metal uptake in lentil plants grown in soil mixed with 20 % sewage sludge. Lentil seeds were inoculated with Rhizobium prior to sowing and with either of the AMF (Funneliformis caledonius or Glomus bagyarajii) in pots filled with soil-sewage sludge mixture. The results showed that the tested microbial inoculum enhanced the growth and productivity of lentil plants. Lentil plants inoculated with Rhizobium and AMF had better nodulation and root colonization, leading to an increase in the nitrogen, phosphorus and potassium (NPK) content and a decrease in the stress marker, proline, in plant parts. In addition, the inoculated microbes also improved the photosynthetic and biochemical contents of the plant. Lentil plants grown in sewage sludge-amended soil when inoculated with Rhizobium and either of AMF were found to be more effective in accumulating Cd, Cr, Pb, Ni, and Zn in the roots, while restricting their translocation to the above-ground parts of the plant, thereby improving plant health. Overall, the study outcomes provide evidence that Rhizobium and AMF have the potential to tolerate heavy metal stress caused by the addition of sewage sludge to soil, which has important implications for sustainable agriculture practices. The study also highlights the importance of microbial inoculants, such as Rhizobium and AMF in enhancing growth and yield, particularly under heavy metal stress in economically important lentil. [ABSTRACT FROM AUTHOR]

The oxyhydrogen flame (OHF) can generate temperatures as high as 2800 K and a jet flow of highly reactive free radicals including H, OH, HO 2 and O. Therefore, it could serve as an effective means for treating various chemical wastes, particularly organic wastes. Building upon our previous research on metal chlorides, we present here a study on the degradation mechanism of aqueous methyl orange (MO) solution under OHF. Although the decolorization of MO solution is rapid, complete degradation is a slow and intricate process. Initially, MO solution undergoes decolorization by breaking the azo bond followed by oxidation processes that convert aminobenzene compounds to benzoquinone and break down the benzene ring until ultimately being fully converted into CO 2 and H 2 O. [Display omitted] • Oxyhydrogen flame (OHF) produces only water and highly reactive radicals. • MO eventually degraded to simplest stable molecules such as CO 2 , H 2 O and N 2 by OHF. • OHF is promising for treatment of organic wastewater without any more waste. [ABSTRACT FROM AUTHOR]

Agricultural waste, called biomass, is of great interest as a renewable energy source. The purpose of this work was to determine the optimal recirculation rate (RR) values of the solid digestate when applying a new approach to the intensification of anaerobic conversion, providing a high quality biogas yield. This approach includes solid digestate recirculation and pre-processing a mixture of raw waste and solid digestate in a vortex layer apparatus. For this, the operation of an experimental biogas plant without recirculation and with recirculation was considered, starting from very low RR values, from 0.034 to 1, to ensure a high methane production rate (MPR) and methane yield (MY). From the point of view of MPR and MY, the recirculation ratios of 0.034 and 0.071 look the most attractive, however, with a recirculation ratio of 0.5, the content of hydrogen sulfide de-creased to 14 ppm with a simultaneous increase in MPR by 12 % compared to the control. [ABSTRACT FROM AUTHOR]

In this work, the effect of ash particle size on the sequential production of bioH 2 and bioCH 4 for biohythane recovery from the organic fraction of municipal solid waste (OFMSW) was investigated for the first time using micro- and nano-sized biomass fly ash (FA). In the first hydrogenogenic stage, the highest bioH 2 yield of 215 mL/g VS added was noticed in the reactor added with micro-sized FA. On the contrary, in the second methanogenic stage, the maximum bioCH 4 yield of 676 mL/g VS added was witnessed in the reactor fed with acidogenic effluent containing nano-sized FA. In the integrated two-stage process, the addition of FA with nano-sized particles showed superiority over micro-sized FA supplementation and led to an increase of about 582 and 595% in organic matter conversion and energy yield, respectively, compared to the control test, as well as achieving biohythane with an optimal hydrogen content of 15% v/v. • The particle size of FA additive affected the two-stage biohythane production. • The maximum bioH 2 yield in the 1st stage was obtained by adding micro-sized FA. • The highest bioCH 4 yield in the 2nd stage was related to the nano-sized FA addition. • The best performance of the two integrated stages was attained using nano-sized FA. [ABSTRACT FROM AUTHOR]

Today, population growth, industrialization and economic growth increase the consumption of fossil fuels to meet the energy demand. The scarcity of fossil fuels and the harmful gases they generate increase the interest in renewable energy sources. One of these sources is hydrogen energy, which is plentiful in nature and has no negative environmental effects. Sodium borohydride (NaBH 4) is a good source of hydrogen, but a catalyst must used for methanolysis. Besides producing energy, it is also important to store it. Supercapacitors are a good alternative to energy storage elements due to their outstanding advantages. In this work, Dunaliella salina (DS) microalgae were used as substrate to synthesize activated carbon for the first time to develop materials that can operate both as a catalyst and an electrode material for supercapacitors. The activated carbon was obtained by carbonization and activation and the taguchi experimental approach was used to minimize the number of experiments. The best hydrogen production rate (HPR) result for DS-9 catalyst with 0.10 g catalyst and 0.25 g NaBH 4 at ambient temperature of 60 °C was determined to be 13,085 mL min−1gcat−1. The material with the best HPR value was then used as the electrode material for supercapacitor design. The specific capacitance value for 1 A/g was determined using galvanostatic charge-discharge (GCD) curves to be 216 F/g. In addition, the produced supercapacitor has an energy density of 13.80 W h/kg at a power density of 480 W/kg. The results indicate that the ecologically friendly and cost effective bifunctional materials produced can be used both in reuse of organic wastes and in catalyst and supercapacitor applications. [Display omitted] • Dunaliella salina was used for the first time as a catalyst in hydrogen production and supercapacitor electrode material. • The best HPR value is obtained 13,085 mL min−1gcat−1. • The produced supercapacitor's specific capacitance 216 F/g for 1 A/g. • The produced supercapacitor has an energy density of 13.80 W h/kg at a power density of 480 W/kg. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is an efficient way to process organic waste to produce biogas. At the same time, one of the stages of anaerobic digestion so called dark fermentation (DF), which makes it possible to obtain biohydrogen. To increase the bioavailability and efficiency of mass transfer between feedstock particles and hydrolytics and, as a result, increase the DF efficiency, it is advisable to pretreat organic waste by various methods. One of the most promising and energy efficient methods of preparing the feedstock for anaerobic fermentation, including DF, is its processing in the vortex layer apparatus (VLA). However, not all aspects of VLA application in anaerobic digestion feedstock pretreatment systems have been fully considered: in order to introduce the VLA into the organic waste DF system, it is necessary to determine, among other things, the energy characteristics of VLA under various modes of its operation, and the data obtained must be used in the development of the energy balance of the anaerobic processing system. Thus, the purpose of this work is to experimentally determine the thermal effects of pretreatment of DF feedstocks in VLA under various modes of its operation using the response surface methodology. To achieve this goal, an experimental setup was developed and created, which made it possible to conduct an experiment based on the central composite design (CCD) using Design-Expert software. The resulting models and their response surfaces have a determination coefficient of more than 0.99, which indicates their adequacy. The coefficient of conversion of electricity into heat on the VLA coil is on mean at the level of 0.54 ± 0.11, and the coefficient of useful use of heat VLA for heating the feedstock is 0.42 ± 0.06, which indicates a high potential for using waste heat. Thus, the obtained models of thermal effects of pretreatment of DF feedstocks in the VLA can be used to determine both the heat directly introduced into the feedstock during pretreatment and the heat removed by the heat exchanger to maintain the VLA operating mode. In this case, the heat removed by the heat exchanger can be used as a source of low-grade heat. [ABSTRACT FROM AUTHOR]

The assessment of anaerobic biotransformation in thermophilic mode (55 °C) of agricultural waste was carried out. It has been established that organic wastes (wheat distillery vinasse, cow manure and chicken manure) have a great potential for producing biogas with a high content of methane and carbon dioxide with a low content of impurities. Biogas can be recommended as a raw material for hydrogen production. With the ratio of components in the composition of the mixed substrate of distillery vinasse, cow manure and chicken manure - 6: 3: 1 for 21–29 days of anaerobic digestion, the best indicators of the efficiency of methanogenesis for methane (61–63%) and biogas (70–73%) were provided, the share of methane in composition of biogas was 61%. With the biotransformation of alone vinasse, the nitrogen mineralization efficiency (58–67%) was lower than when using a mixture of organic waste (63–69%). From the point of view of obtaining the maximum amount of biogas, it is advisable to add a carbonate buffer or limestone flour (9% wt.) to the substrate to shift the pH of the working solution towards slightly alkaline values. From the point of view of the accumulation of free phosphates in the final solution, the use of a carbonate buffer is more preferable. The anaerobically treated solid sludge remaining after biogas production, as well as liquid effluents (anaerobically treated effluents) can be considered as potential organic and biogenic fertilizers or their components. [ABSTRACT FROM AUTHOR]

Solar-powered photoreforming of plastics provides a facile and low-energy pathway for generating green hydrogen while converting plastic wastes into valuable organic compounds. Herein, a Z-scheme photocatalyst, containing Cd 0.5 Zn 0.5 S for hydrogen production, red phosphorus (RP) for oxidizing plastics, and Co x P y as the electron mediator, was constructed. The photoreforming of polylactic acid (PLA) and polyethylene terephthalate (PET) was carried out under alkaline aqueous conditions. The photogenerated electrons from the RP recombined with the holes from Cd 0.5 Zn 0.5 S. The retained electrons in Cd 0.5 Zn 0.5 S reduced water to hydrogen, whereas the holes in the RP oxidized plastic-derived polymers into valuable organic products, such as pyruvate, acetate, and methanol. The hydrogen evolution rates from the photoreforming of PLA and PET using the optimal photocatalyst at 35 °C reached 503.9 and 74.4 μmol h−1, corresponding to the apparent quantum efficiencies of 5.84 % and 0.89 % at 420 nm. Z-scheme photocatalyst RP@Co x P y /Cd 0.5 Zn 0.5 S was built to achieve hydrogen production coupled with photoreforming of PLA and PET into valuable organic products. [Display omitted] • Photoreforming of plastics combined with hydrogen production is realized. • A Z-scheme photocatalyst is built to enhance the performance. • Polylactic acid (PLA) and polyethylene terephthalate (PET) are used. • Waste plastics are converted into valuable organic products. • The apparent quantum efficiencies of 5.84 % and 0.89 % are obtained. [ABSTRACT FROM AUTHOR]

Sewage sludge as a byproduct of industrial and municipal wastewaters treatment is produced worldwide at large quantities. This organic waste contains nutrients, pathogens, heavy metals, organic pollutants and other toxic substances. In recent years, the significant increase in the amount of sludge as an important environmental issue, which is considered both a threat and an opportunity, has highlighted the issue of its proper management. In recent decades, various methods have been used to manage and energy recovery from sewage sludge, including pyrolysis, incineration, gasification, anaerobic digestion, aerobic digestion, landfill, composting, lime and microbial fuel cell. Nowadays bioenergy production from sewage sludge attracted the attention of environmentalists due to environmental and economic considerations. In this regard, microbial fuel cells (MFCs) have gained a great importance as an alternative energy conversion method for bioenergy production. This system converts the chemical energy in the organic substance directly into valuable electrical energy by the catalytic reaction of microorganisms. The effectiveness of the system depends on the reactor configuration, operational and environmental parameters. Identifying and optimizing these parameters are important to increase the system efficiency. In this paper, we reviewed and discussed the effects of different parameters on the treatment and electricity generation from waste activated sludge (WAS) using MFC system such as nature of electrode materials, oxygen flow rate, reactor design, substrates and pH. Furthermore, a better understanding of the MFCs performance for bio-fuel generation from WAS, as well as solving concerns associated to the abilities of this technology in real application is aims of this review. [Display omitted] • To power generation and sewage sludge stabilization, simultaneously. • Impact of configurations and operation of MFC on sewage sludge stabilization. • To study the factors influencing the sewage sludge treatment and power generation by MFC. [ABSTRACT FROM AUTHOR]

The syngas of organic solid waste (OSW) obtained through gasification is of great interest in energy and fuel production owing to its clean and environmentally friendly characteristics. In this study, the physicochemical properties of typical OSW were systematically studied, and the mechanism of the influence of OSW sample structure and composition on gasification behavior was studied by thermogravimetric mass spectrometry and gasification experiments. Scanning electron microscopy was used to observe the surface morphology of the samples, showing that waste wood chips (WWC) and Pennisetum giganteum (PG) have well-developed pore structures. Fourier transform infrared spectroscopy results indicated that polyurethane foam (PF) and polyethylene terephthalate (PET) have more oxygen-containing functional groups than WWC and PG. X-Ray diffraction showed that the order of crystallinity index was WWC > PET > PF > PG. X-ray photoelectron spectroscopy results showed the order of the surface alkali content was PG > PF > WWC. Furthermore, thermogravimetric and mass spectrometry experiments were used to explore the components released from volatiles during heating, demonstrating that WWC and PG produce mainly H 2 O, while PF and PET produce mainly CO 2. Gasification experiments were carried out at different heating rates, and PET had the highest initial and final gasification temperatures. The distributed activation energy model was used to calculate the apparent activation energy, which was in the order WWC (153.7 kJ/mol) > PET (136.9 kJ/mol) > PG (81.2 kJ/mol) > PF (78.9 kJ/mol) and was consistent with the carbon ordering degree result. [Display omitted] • The relationship between the structure and gasification mechanism was explored. • The distributed activation energy model was used to calculate activation energy. • Clarifying the evolution behavior of small molecular gas from different wastes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of CO 2 atmosphere on biochar production and properties was studied. • Compared to inert N 2 , CO 2 significantly affects the pyrolysis products. • CO 2 promotes biochar yields (400–600 °C) for all feedstocks. • Surface area and porosity of biochar can be improved using CO 2 in pyrolysis. • CO 2 biochar contained higher C, lower O/C and O/H ratios. Slow pyrolysis, a widely recognized thermochemical technique, is employed to produce biochar usually under inert atmospheres. Recently, there is a growing interest in utilizing CO 2 as a carrier gas during pyrolysis as an alternative to inert atmospheres, aiming to modify the resulting pyrolytic products and make them suitable for different applications. This study investigated and compared the impact of CO 2 atmosphere with N 2 on pyrolysis of food waste, rice husk, and grape tree branches waste via slow pyrolysis at temperatures of 400, 500, and 600 °C at 5 and 15 °C/min for 1 h, to evaluate biochar production and its properties. The results demonstrate that CO 2 atmosphere increased the biochar yield for all feedstocks and significantly influenced the physicochemical properties of biochar. Compared to N 2 , CO 2 -derived biochar exhibited less volatile matter, higher carbon content, lower O/H and O/C molar ratios and enhanced textural properties. This study highlighted the potential of utilizing CO 2 for biochar production and tailoring biochar properties for specific applications and the findings contribute to the establishment of sustainable and efficient waste management systems and the production of value-added biochar products. [ABSTRACT FROM AUTHOR]

[Display omitted] The global municipal solid waste (MSW) generation rate is 2.01 billion metric tonnes annually with an average of 0.74 kg waste/person/day. Approximately 92 % of the MSW originates from organics composition (e.g., food waste; plastic; paper; garden waste/woods, and textile), where 33 % of overall MSW is improperly managed in an efficient and environmentally safe manner. One of the promising methods to solve MSW management issues is to convert MSW into refuse-derived fuel (RDF) that can be used for the clinker burning process in cement kiln to replace the usage of fossil-based solid fuel. Thus, the potential of local MSW composition in energy recovery; suitability of RDF production technology; as well as international-industry requirement on RDF in co-processing and environmental concerns are discussed. Due to heterogeneous composition and sizes in nature, high moisture, and substantial amount of chloride content in MSW, it needs to undergo pre-treatment processes to enhance the RDF's physio-chemical properties that comply with RDF ASTM/EN standards, where expected high heating value (HHV) is > 20 MJ/kg, ash (<10 %), Chloride (Cl) (<0.80 – 1.00 %), Sulphate (S) (<1.50 %), Nitrate (N) (<1.00 %). As the development of upgraded MSW to RDF is still new in the commercial phase, there is minimal information and data on the techno-economic analysis, as well as recent industrial-scale of thermos-chemical conversion technologies for RDF preparation. Hence, the present work provides a clear picture on overview of municipal solid waste (MSW) generation, MSW composition, MSW pretreatment, and application as co-processing in cement industry are discussed. Besides, recent thermochemical upgrading process (torrefaction, dry carbonization, and hydrothermal carbonization) of MSW from R&D to commercial scale was further highlighted. In summary, this review serves as basic criterion and strategies to explore the new path of upgrading the waste into RDF for the purpose of sustainable energy recovery that adopting in circular carbon economy framework. [ABSTRACT FROM AUTHOR]

In this research, synthesis, characterization, and photocatalytic degradation of zeolitic imidazolate framework-11 was investigated. This framework was synthesized through a solvothermal method using the polar solvent, methanol. The characterization analysis included X-ray diffraction analysis, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, Brunauer-Emmett-Teller, Fourier-transform infrared spectroscopy, and contact angle measurement; which have been discussed to characterize the as-synthesized nanostructure zeolitic imidazolate framework-11 (ZIF-11). As a result of diffuse reflectance spectroscopy analysis, ZIF-11 was recognized as photoactive with a band gap of 5 eV. The contact angle in the synthesized photocatalyst was 166° showing that it is hydrophobic. Evaluating the effect of operational factors including pH, photocatalyst dosage, and aeration pump flow rate in the photodegradation process was done by performing 22 experiments via Design-Expert software through the response surface method. The most and least effective parameters were identified as pH and aeration pump with contribution percentages of 33.82 and 2.57, respectively. A quadratic theoretical model with a P-value of less than 0.0001 for the photodegradation process was obtained. The optimal degradation percentage of methylene blue as organic waste, in minimum aeration pump level, pH equal to 10, and 0.2 g of the photocatalyst was observed to be 83.88% under UV light irradiation in 30 min. The value obtained for R-squared in this model was 0.9996, which would validate the accuracy and adequacy. [ABSTRACT FROM AUTHOR]

Biomass gasification technology has gained significant attention as a potential solution for circular economies by converting organic waste into valuable energy and products (Waste-to-Power-to-X). This paper comprehensively evaluates biomass gasification technology from a techno-economic-policy perspective, providing valuable insights for circular economies. It examines technical aspects such as processes, feedstocks, and syngas production, assessing advancements that would improve efficiency and environmental performance by addressing key challenges like tar removal and gas cleaning. Economic feasibility is analysed through a techno-economic assessment, considering capital costs, operational expenses, revenue streams, and potential markets. Real-world examples and case studies offer insights into economic viability of these processes. The paper emphasizes the significance of supportive policy frameworks, discussing stimulus measures like feed-in tariffs, tax incentives, and regulatory reforms to promote biomass gasification adoption. By combining technological, economic, and policy perspectives, this paper provides a holistic reality check of biomass gasification technology, identifying opportunities, challenges, and pathways for leveraging as a sustainable and economically viable solution for waste management and energy production. The findings and insights presented in this paper can assist policymakers, investors, and stakeholders in making informed decisions regarding the implementation of biomass gasification projects in the future. [Display omitted] • These findings serve as valuable insights for exploring the market potential. • Waste materials are transformed into valuable resources. • Effectively managing by-products is crucial in unlocking their economic potential. [ABSTRACT FROM AUTHOR]

[Display omitted] • The interaction mechanisms between Cd/Pb and kaolinite surfaces are explored. • The adsorption stability on the -H + Fe surface follows CdCl 2 < PbCl 2 < Cd0 < Pb0. • The electronic structure is analyzed from charge transfer and chemical bonding. • The active sites on the -H + Fe surface are the O atoms close to the Fe atom. Incineration of organic solid wastes is accompanied by the heavy metal emission through flue gas. As an inexpensive and efficient heavy metal adsorbent, the improvement of kaolinite adsorption performance for heavy metals has drawn widespread interests. In this work, the interaction mechanisms between various kaolinite surfaces and Cd/Pb species are explored through first principles calculations. The results show that the combination of Fe doping and dehydroxylation enhances the activity of kaolinite surfaces, analysis of adsorption configurations reveal that both Cd and Pb species are immobilized through chemisorption on the -H + Fe surface. At the microscopic level, further electronic structure analysis shows that the composite modified kaolinite surface has more electron transfer and more pronounced orbital hybridization and overlap compared to the original kaolinite surface, demonstrating that the modification means of dehydroxylation and Fe doping indeed enhanced the activity of the kaolinite surface, especially the activity of the O atoms in the vicinity of the Fe atom and that the O atoms are more efficiently bonded as ionic connecting Cd/Pb species for the purpose of trapping Cd/Pb species. This study points out the research direction and provides basic theoretical support for the development of new kaolinite adsorbents in the future. [ABSTRACT FROM AUTHOR]

• The collected stored methane is accumulated in an average of 2.5 h. • Shutdown should be done 3.1 h before Hydro-Quebec's consumption peak. • Collected stored methane represents 10.5% of methane flow. Landfills are extensively applied to dispose of municipal solid wastes in developed and developing countries. Landfill gas generation from biodegradable organic wastes can be collected and converted to energy. When the gas collection system is shutdown, some of this gas can accumulate and be stored inside the landfill. Using the gas storage capacity of the landfill gets a better management of the landfill site because the collected stored gas could transform the landfill into a cheap gas storage system to provide short-term energy and use the energy when needed. This novel study analyzes the stored methane using the gas collection data of a landfill in Quebec province, Canada, for modulating energy production from landfill gas. Twenty episodes of the gas collection system's shutdown and restart as well as different gas flow durations were studied. The results showed that the collected stored methane is accumulated in an average of 2.5 h. Additionally, the collected stored methane represents 10.5% of landfill gas flow. Although the results are site-specific, the methodology of this paper can be used on other landfill sites with similar size and collection conditions. Designing new landfills could take into consideration some elements to enhance gas storage capacity. For instance, designing landfill daily covers with more granular materials and higher porosities can be the next step to enhance the landfill as a gas storage system during shutdowns. [ABSTRACT FROM AUTHOR]

[Display omitted] • NaOH and KOH pre-treatment enhanced solubilisation of paunch solid waste. • Cattle and sheep paunch was compared at lignocellulosic composition level. • Paunch digestion hydrolysis rate was significantly enhanced by up to 4.4 times. • Paunch digestion methane yield was improved by 60% using alkaline pre-treatment. • First-time addressing alkaline pre-treatment using [OH−] molar concentration. Paunch is comprised of the partially digested feed contained in cattle or sheep and contributes 20–50% of organic waste produced at red meat processing facilities. Anaerobic digestion has been identified as a promising technology for paunch treatment, however treatment times can be long and when combined with the moderate degradability of paunch this results in high treatment costs that need to be improved. Pre-treatment was investigated as a strategy to improve AD of paunch, alkaline treatment (NaOH or KOH) was selected due to the high lignin content. A range of alkaline loadings (1–20 g 100gTS−1) were tested with an equivalent hydroxide molar concentration of 9–250 mM [OH−]. Alkaline pre-treatment improved both the hydrolysis rate and the overall degradability of paunch solid by up to 4.4 times and 60%, respectively. The enhanced hydrolysis rate and methane yield was correlated to changes in material composition during pre-treatment. While alkaline concentration was an important factor, there were no significant improvements at alkaline concentrations above 12 g 100gTS−1 (150 mM [OH−]). [ABSTRACT FROM AUTHOR]