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The acceleration of urbanization has intensified the strain on sewage treatment systems. Research on reducing, rendering harmless, and resourcefully treating organic solid waste has gained significant attention. This study begins by outlining the current state of sludge treatment in China, followed by a review of advancements in pyrolysis, biological treatment, and gasification technologies. It systematically categorizes, compares, and summarizes influencing factors, and process mechanisms of various technologies. The paper focuses on the distinctive features of different processes, emphasizing the high-value utilization of three-phase products and the optimization of reaction conditions. In addition, it provides insights into enhancing the resource utilization of sludge and solid waste, as well as optimizing treatment technologies. This paper aims to consider the ecological environment and economic benefits of the efficient treatment of solid organic waste. It provides reference for industrial application, and contributes to the building of a resource-saving and environmentally friendly society. [ABSTRACT FROM AUTHOR]

The efficient utilization of organic solid waste resources can help reducing the consumption of conventional fossil fuels, mitigating environmental pollution, and achieving green sustainable development. Due to its dual nature of being both a resource and a source of pollution, it is crucial to implement suitable recycling technologies throughout the recycling and upgrading processes for plastics and biomass, which are organic solid wastes with complex mixture of components. The conventional pyrolysis and hydropyrolysis were summarized for recycling plastics and biomass into high‐value fuels, chemicals, and materials. To enhance reaction efficiency and improve product selectivity, microwave‐assisted pyrolysis was introduced to the upgrading of plastics and biomass through efficient energy supply especially with the aid of catalysts and microwave absorbers. This review provides a detail summary of microwave‐assisted pyrolysis for plastics and biomass from the technical, applied, and mechanistic perspectives. Based on the recent technological advances, the future directions for the development of microwave‐assisted pyrolysis technologies are predicted. [ABSTRACT FROM AUTHOR]

This work focuses on analyzing the physical composition of municipal solid waste (MSW) and the physicochemical characterization of the organic fraction of municipal solid waste (OFMSW) in a city in Northeast Mexico to propose an adequate treatment and valorization system. Diverse samples were analyzed over 5 months at the city of Saltillo landfill, where the daily discarded MSW was classified into household (HW), central market waste (CMW), and public areas and parks waste (PPW). For the HW and CMW, the fraction with the highest proportion was the organic residues from food products, with 22.15 and 25.78%, followed by other organic wastes (manure, yard waste, leaves, etc.) at 12.58 and 10.24%, respectively. Furthermore, the organic fraction was segregated from the rest of the MSW and classified into four subtypes, and their physical composition and physicochemical characteristics were determined. The results contribute to laying the foundations for the proper treatment of the OFMSW not just in the studied region but also in cities with similar conditions. Moreover, the OFMSW's feasibility in treating via bioenergy technologies is revealed, and this research proposes a biorefinery treatment pathway through dark fermentation followed by high solids anaerobic digestion generating bioenergy and diverse bioproducts. [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]

The principle and realization approach, the internal relationship between technical advantages and microbial community stnicturc succession in the treatment of organic solid waste using hjprrthcrmo-philic aerobic composting were reviewed・ The engineering application eases of hjperthermophilie composting in the treatment of livestock manure, sewage sludge and food waste was cluciciatcd. and the process parameters of hjprrthcrmophilic aerobic oomposting in the engineering application of organic solid waste were summarized・ Tho excellent application effect of hjprrthcrmophilic aerobic composting in the resource utilization treatment of organic solid waste was demonstrated. The research prospects of organic solid waste treatment by hyprrthcrmophilic aerobic composting in terms of microbial community synergy mechanism, enhanced nitrogen and carbon rctrntion, and optimized process operation were proposed, in order to prondc theoretical basis for the application and promotion of this technology. [ABSTRACT FROM AUTHOR]

Traditional methods for evaluating the bioconversion capacity of organic solid waste are known for time-consuming property and often exhibit low prediction accuracy. However, leveraging fractal dimensions offers a more precise characterization of the complexity, irregularity, and spatial structure of organic solid waste. In this study, a novel and efficient method for evaluating the bio-accessibility of straw's anaerobic transformation, based on fractal dimensions, was introduced. To comprehensively compare the structural differences, this research encompasses the measurement of nine different varieties of straw under ten distinct pretreatment conditions. The regression sum of squares for these correlations consistently exceeds 0.83, highlighting the robustness of our findings. The results unequivocally demonstrate the close relationship between the fractal dimension and the structural characteristics of straw. This relationship underscores the utility of fractal dimension analysis as a reliable tool for evaluating the anaerobic bio-accessibility of organic solid waste.

The rapid growth of organic solid waste has recently exacerbated environmental pollution problems, and its improper treatment has led to the loss of a large number of biomass resources. Here, we expound the advantages of microbial agents composting compared with conventional organic solid waste treatment technology, and review the important role of microbial agents composting in organic solid waste composting from the aspects of screening and identification, optimization of conditions, mechanism of action, combination with other technologies and ultra‐high‐temperature and ultra‐low‐temperature microbial composting. We discuss the value of microorganisms with different growth conditions in organic solid waste composting, and put forward a seasonal multi‐temperature composite microbial composting technology. Provide new ideas for the all‐round treatment of microbial agents in organic solid waste in the future. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau is an important ecological security barrier in China. Considering the rich local waste biomass with a single treatment method and low level of resource utilization, biochar utilization of solid waste biomass can be carried out based on the research that biochar has abundant material sources. According to the application methods of various types of solid waste resources that have not been carried out, this review analyzes and discusses various types of waste biomass resources in the plateau region, such as sewage plant sludge, food waste, green leaves, barley straw, yak manure, and the unique Tibetan tea and Tibetan medicine residue waste, and reviews the biochar methods and applications for similar raw materials at home and abroad. Further, the technical outlook of solar pyrolysis technology and UV radiation modification technology and the development of hybrid pyrolysis to enhance the performance of biochar materials and heavy metal passivation are proposed by utilizing the solar energy resources of the Tibetan Plateau. Collectively, it provides a reference for prevention and restoration methods for the fragile ecological environment of the Qinghai-Tibet Plateau, reduces the pressure of waste disposal in the region, and realizes the resource utilization of waste. [ABSTRACT FROM AUTHOR]

As an important resource insect, black soldier fly (BSF) can treat a variety of organic solid wastes and harvest insect biomass. BSF is rich in protein, fat and other nutrients. It can effectively replace fish meal and soybean meal as a new feed protein resource in the feed of livestock, poultry and aquaculture. BSF larvae also can effectively reduce the carbon emissions in the treatment process and fix more carbon elements in the form of organic matter on insect biomass. This paper provides a review from the following aspects: the conversion of different organic solid wastes by black soldier fly, Influence of different organic solid waste mixture on conversion and BSF nutrition; influence of microorganisms on the conversion of organic solid waste by black soldier flies to obtain BSF biomass and protein, harmless conversion of organic solid waste, fish meal and soybean meal could be replaced by BSF, which is a highly promising new type of "open source" feed protein; development and utilization of functional proteins (peptides) in black soldier flies - used for feed protein throttling, the role of black soldier fly in carbon sequestration and emission reduction; at the same time, the future research and development directions of the black soldier fly were discussed, to provide reference for the development and utilization of black soldier fly resources. [ABSTRACT FROM AUTHOR]

Two-stage anaerobic digestion and trace metals (TM) supplementation are promising techniques to improve biogas production. Fe2+ and Ni2+ can improve process stability since they are part of the cofactors of enzymes and microorganisms' growth. This work attempted to evaluate the effect of Fe2+ and Ni2+ addition on H2-rich biogas production from organic solid waste and the CH4-rich biogas production from the acidogenic effluents (AEs) enriched with TM. The TM concentrations that enhanced the hydrogen yield in the batch were 0.25 mg/L of Ni2+ and 334 mg/L of Fe2+. These concentrations were evaluated in a two-stage system. The substrate for the batch tests and fermentative reactor (first stage) was OSW. The AE generated in the first stage was the substrate to produce CH4-rich biogas in the second stage. In the first stage, the productivity achieved was 1823 ± 160 mL H2/L/day. However, TM supplementation decreased productivity by 65% since the VS removal increased. Megasphaera genus predominated in the first stage. Regarding the methanogenic reactor, the undiluted AE without TM caused the fast decay of the process. Nevertheless, the reactor operated stably after using AE enriched with TM as a substrate, and CH4 yields increased by 42%. The highest productivity achieved in the second stage was 1278 ± 42 mL CH4/L/day, operating with an organic loading rate of 2.8 gVS/L/day. The genera Proteiniphilum, Thermovirga, DMER64, Anaerovorax, and Syntrophomonas predominated in the second stage. In conclusion, AE enriched with TM can be used to recover the stability of anaerobic digesters, increasing methane production. [ABSTRACT FROM AUTHOR]

Different strategies have been tested to reduce nitrogen losses and gaseous ammonia emissions during composting. Among them, the supplementation of the composting mixture with biochar has shown good results and has attracted increasing attention from researchers over more than a decade. In order to capitalise on the numerous existing results, the relevant data from the literature were subjected to descriptive statistics and to a Pearson parametric correlation analysis. The statistical treatment of the literature data confirms that biochar reduces nitrogen losses, ammonia and nitrous oxide emissions during composting with highly variable performance (respectively reduction of 26.2% ± 16.7%; 46% ± 26.4%; 46.1% ± 31.1%). Statistically significant correlations were identified between N losses and biochar properties. However, the PCA results show that only 44.75% of the variability in the N loss reduction dataset and 57.8% of the ammonia emission reduction dataset were explained by the main variables available in the literature. This suggests that much of the variability in biochar performance remains unexplained. The large number of variables involved in the process and the lack of fine characterisation of biochar in most studies explain the remaining difficulty in fully understanding the complex action of biochar in composting and opens up prospects for further research. [ABSTRACT FROM AUTHOR]

Organic solid waste is a renewable resource as it can be transformed into a valuable product through various technologies. Composting is considered to be the most economical and effective technology for treating organic solid waste, but excessive amounts of heavy metals in organic solid waste compost are harmful to the environment. The current focus is on the addition of heavy metal passivators to organic solid waste to reduce the mobility and biotoxicity of heavy metals in situ or ex situ. The aims of this paper are to provide an overview of heavy metal passivators and their passivation mechanisms in the field of organic solid waste composting and to provide a reference for research on the control of heavy metal pollution in the treatment of organic solid waste. [ABSTRACT FROM AUTHOR]

The impact of inoculum (mature compost) was assessed in an aerobic system for the rapid degradation of organic solid waste, with a focus on the release of reducing sugars. Isothermal (35 and 55 °C) and non-isothermal (35-55°C) treatments were conducted. Key indicators, including the rate of oxygen consumption (O2) and carbon dioxide production (CO2), were measured to assess microbial activity. Additionally, the concentration of reducing sugars, pH, enzymatic activity, and the presence of pathogens were evaluated. Treatments with inoculum at 35 °C and without inoculum at 55°C exhibited an increase in oxygen consumption and CO2 production, indicating heightened microbial activity and, consequently, greater mineralization of organic matter. The treatment without inoculum at 35-55 °C presented the highest concentration of reducing sugars (160 mg/g dry weight), suggesting its potential as a pretreatment for bioconversion processes aimed at generating value-added products. At a temperature of 55°C, there was a reduction of 84.4, 87.28, and 67.33% in the concentrations of fecal coliforms, Escherichia coli, and parasites, respectively. This result suggests that elevated temperature contributes to the effectiveness of pathogen elimination. [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]

Waste management is a significant and widespread issue that challenges many countries, particularly developing countries. Organic waste is a primary contributor to greenhouse gas (GHG) emissions in waste management, making it a crucial problem to address. Proper waste management practices, including decentralized organic waste management, are necessary to address this issue. However, this decentralization requires the support of the community’s waste segregation behavior. Therefore, this study was conducted in Sukmajaya and Cilodong Districts to analyze the intention of organic waste sorting behavior utilizing Theory of Planned Behavior (TPB) analysis. The results showed that only two constructs, attitude and perceived behavioral control, positively impacted the intention to sort organic waste. In this study, norm construction does not serve as a supporting construction for the waste sorting intention. Additionally, knowledge of waste sorting programs and activities significantly affects perceived behavioral control. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper conducts an in-depth study on the gasification treatment of Organic Solid Waste (OSW) and its carbon emissions, intending to fill the gap in the existing literature regarding the calculation methods for carbon emissions from OSW gasification. The study establishes a methodology for calculating carbon emission factors during the OSW gasification process and explores the potential for negative carbon emissions. For this purpose, indicator including the Carbon Dioxide Equivalent Warming Number (CEWN) is used to assess the greenhouse gas emissions of the gasification process by calculating carbon emission factors under different gasification conditions. It is found that within a certain range, increasing the gasification temperature, Equivalence Ratio (ER), and Steam to Biomass ratio (S/B) can positively influences the achievement of negative carbon emissions. These findings hold significant implications for optimizing the OSW gasification process, reducing carbon emissions, and ultimately achieving carbon neutrality. Furthermore, this study fills a critical void in the gasification field within the IPCC framework and offers essential guidance for promoting to achieve peak carbon emissions in the gasification industry and accelerating the goal of carbon neutrality.

Methanation is an effective way to efficiently utilize product gas generated from the pyrolysis and gasification of organic solid wastes. To deeply study the heat transfer and mass transfer mechanisms in the reactor, a successful three-dimensional comprehensive model has been established. Multiphase flow behavior and heat transfer mechanisms were investigated under reference working conditions. Temperature is determined by the heat release of the reaction and the heat transfer of the gas-solid flow. The maximum temperature can reach 951 K where the catalyst gathers. In the simulation, changes in the gas inlet velocity and catalyst flow rate were made to explore their effects on CO conversion rate and temperature for optimization purposes. As the inlet gas velocity increases from 2.78 to 4.79 m/s, the CO conversion rate decreases from 81.6% to 72.4%. However, more heat is removed from the reactor, and the temperature rise increases from 78.03 to 113.49 K. When the catalyst flow rate is increased from 7.18 to 17.96 kg/(m²·s), the mass of the catalyst in the reactor is increased from 0.0019 to 0.0042 kg, and the CO conversion rate is increased from 66.8% to 81.5%. However, this increases the maximum temperature in the reactor from 940.0 to 966.4 K. [ABSTRACT FROM AUTHOR]

This work evaluated the performance of thermophilic aerobic co-composting of municipal sludge and blue-green algae and explored the dissolved organic matter dynamic evolution simultaneously. The results of 28-day monitoring demonstrated that the addition of blue-green algae greatly upgraded the municipal sludge thermophilic aerobic composting performance with the highest microcystin removal efficiency averaging 94.9%, germination index over 90% and moisture content below 45% at municipal sludge: blue-green algae ratio of 4:1. The synergistic effect of municipal sludge and blue-green algae enhanced microbial activity through creating a better aerobic composting environment and, therefore, improved the permeability of the input streams. Three-dimensional excitation-emission matrix spectra of the input streams were resolved by the parallel factor analysis model, and the main components were humic acid-like (Component 1), fulvic acid-like (Component 2), tryptophan-like (Component 3), and tyrosine-like (Component 4). In addition, the relative Fmax of Component 1 and Component 2 increased during aerobic composting, while the Fmax of Component 3 and Component 4 decreased sharply. The variation indicated that aerobic co-composting could enhance the decomposition of protein-like substances and promote the generation of humus-like substances, thus leading to the increased humification. Hence, the aerobic co-composting of municipal sludge and blue-green algae provided important theoretical support for the scale-up engineering treatment of MS. [ABSTRACT FROM AUTHOR]

Supercritical water gasification (SCWG) is one of the typical hydrothermal treatment technologies for organic solid waste. However, the current SCWG optimization methods perform deterministic optimization without considering the uncertainty of the model for calculating the objective function, which leads to low reliability of the optimization results. Therefore, an optimization framework that considers the prediction uncertainties of SCWG data-driven models is proposed to optimize the H 2 yield and cold gas efficiency of organic solid waste SCWG. An ensemble prediction model integrating random forest, gradient boosting regression, and K-nearest neighbor algorithms by the stacking learning method are built to predict SCWG gas yields. The cold gas efficiency prediction model is constructed based on the gas yield prediction models. The SCWG optimization models are constructed by combining the H 2 yield and cold gas efficiency prediction models. The uncertainties in the H 2 yield and cold gas efficiency prediction models are analyzed and integrated into the optimization models. The case studies were conducted to test the proposed framework. The optimization results were verified by the results of similar experimental conditions. It demonstrates that the proposed framework can obtain the robust results of the organic solid waste SCWG optimization, which can provide a reference for SCWG optimization. • A novel ensemble prediction model is built to predict the SCWG performance. • SCWG optimization model is constructed by combining the ensemble model. • Uncertainties are modeled and integrated to improve robust results. • H 2 yield and cold gas efficiency are optimized by the WOA algorithm. [ABSTRACT FROM AUTHOR]

At present, organic solid waste composting products have difficulties in applications and markets. The main reasons why composting products lose markets are analyzed: ①Changes in the way of production and life have led farmers to abandon the composting tradition; ②The high cost-effectiveness ratio of composting has led farmers to abandon composting; ③Organic solid waste composting has certain safety risks and quality problems. In view of the existing problems, some suggestions from the aspects of developing the agricultural mode integrated planting and raising, developing the large-scale management mode, establishing the safety classification standard of compost, opening up new ways of using compost, developing and popularizing more advanced and economical composting technology are put forward, in order to provide ideas for solving the outlet problems of composting products. [ABSTRACT FROM AUTHOR]

At present there is a great advance in the use of organic substances as fertilizers; humic substances are one of them with various forms of extraction. This article evaluates the extraction yield of humic substances (humic acid and fulvic acid) from three raw materials and different basic extractants and acids. In the basic extraction of humic substances, the type of raw material significantly influences, to a p value equal to 5 %. The maximum extraction volumes of humic substances are with garden waste. The fractionation stage of the humic and fulvic acids (acid extraction) depends on the type of basic extractant. The alternative Vermicompost - NaOH - HCl is the most economic and technically feasible, with 38.53 % of extraction yield value of humic acid and 64.90 $/h of gross profit. [ABSTRACT FROM AUTHOR]

A series of complex thermochemical reactions occur in the thermal conversion process of organic solid waste, which brings challenges to the in-depth understanding of its mechanism, the optimization of technical parameters for the conversion process and the directional regulation of products. The data-driven machine learning modeling method can promote the intelligence and refinement of organic solid waste disposal. In this review, the application of the intelligent modeling method based on machine learning in the whole chain disposal of organic solid waste was summarized. The prediction of machine learning on the upstream production and physical and chemical characteristics of organic solid waste, the thermal conversion process and product characteristics in the middle stream, and the utilization and benefit evaluation of downstream products were reviewed. The applicable scenarios, advantages and disadvantages of different models were compared. The purpose was to construct an intelligent disposal scheme for the whole chain of organic solid waste, and realize an efficient disposal mode of organic solid waste integrating harmlessness, reduction, resource utilization, high value and intelligence, and to provide some guidance for the effective management of solid waste.

The research status of traditional gasification technology for hydrogen production from organic solid waste are reviewed, the influence of three main factors, gasification medium, gasification temperature and catalyst, on hydrogen production effect is analyzed in detail, by analyzing the action mechanism and summarizing the advantages and disadvantages in the application process, the technical disadvantages of this technology are put forward purposefully, it is pointed out that the technology should be developed from four aspects: mechanistic exploration, development of high-performance composite catalyst/catalyst with special structure, development of hydrogen production technology by co gasification with coal, and coupling with other new gasification hydrogen production technologies in the future, so as to better promote the industrial application of the technology. [ABSTRACT FROM AUTHOR]

Organic solid waste (OSW) contains many renewable materials. The pyrolysis and gasification of OSW can realize resource utilization, and its products can be used for methanation reaction to produce synthetic natural gas in the specific reactor. In order to understand the dynamic characteristics of the reactor, a three-dimensional numerical model has been established by the method of Computational Fluid Dynamics (CFD). Along the height of the reactor, the particle distribution in the bed becomes thinner and the mean solid volume fraction decreases from 4.18% to 0.37%. Meanwhile, the pressure fluctuation range decreased from 398.76 Pa at the entrance to a much lower value of 74.47 Pa at the exit. In this simulation, three parameters of gas inlet velocity, operating temperature and solid particle diameter are changed to explore their influences on gas-solid multiphase flow. The results show that gas velocity has a great influence on particle distribution. When the gas inlet velocity decreases from 6.51 to 1.98 m/s, the minimum height that particles can reach decreases from 169 to 100 mm. Additionally, as the operating temperature increases, the particle holdup inside the reactor changes from 0.843% to 0.700%. This indicates that the particle residence time reduces, which is not conducive to the follow-up reaction. Moreover, with the increase of particle size, the fluctuation range of the pressure at the bottom of the reactor increases, and its standard deviation increases from 55.34 to 1266.37 Pa. [ABSTRACT FROM AUTHOR]

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study addresses the issues of difficult to treat organic solid waste and significant secondary pollution generated in the current steelmaking process by using the RHF process. Using pyrolytic slag of waste cloth and mill roll sludge produced in steel plants as raw materials, this study explores the feasibility of replacing part of the carbon powder with organic solid waste to produce metallized pellets. The results indicate that this method is feasible. With 12 % carbon addition, a roasting temperature of 1200 °C, a roasting time of 30 min, and a pellet size of 12 mm–14 mm, the metallization rate and de‑zincification rate of the pellets produced with organic solid waste replacing part of the carbon powder are both improved compared to those with full carbon powder. The metallization rate of these pellets can exceed 90 %, and the de‑zincification rate can consistently remain above 99 %. [Display omitted] • A new method to synergistic utilization of zinc-bearing dust and organic solid waste • Organic solid waste replaces carbon powder in the production of metallization pellets • Metallization and dezincification rates of metallized pellets are enhanced [ABSTRACT FROM AUTHOR]

Organic solid waste is a renewable resource as it can be transformed into a valuable product through various technologies. Composting is considered to be the most economical and effective technology for treating organic solid waste, but excessive amounts of heavy metals in organic solid waste compost are harmful to the environment. The current focus is on the addition of heavy metal passivators to organic solid waste to reduce the mobility and biotoxicity of heavy metals in situ or ex situ. The aims of this paper are to provide an overview of heavy metal passivators and their passivation mechanisms in the field of organic solid waste composting and to provide a reference for research on the control of heavy metal pollution in the treatment of organic solid waste.

The gasification kinetics of pellets obtained from organic solid wastes (OWS) and raw materials were studied using the Coats–Redfern and DAEM methods. The different methods were comparatively analyzed for mutual verification, and the similar activation energies obtained by each method affirmed the accuracy of the kinetics calculation. Overall, the activation energies of the char gasification stage ranged from 200 to 265 kJ mol−1, higher than those of the devolatilization stage, which ranged from 130 to 200 kJ mol−1 for all pellets and raw materials. During the devolatilization stage, the activation energies of the pellets were invariably higher than those of their corresponding raw materials, which was the opposite for the char gasification stage. A detailed comparison between the calculation results from the Coats–Redfern and DAEM methods confirmed that the devolatilization stage is controlled by one-dimensional diffusion, and the gasification stage is controlled by two-dimensional or three-dimensional diffusion for pellets and raw materials. [ABSTRACT FROM AUTHOR]

• A scheme of HTC coupled with co-gasification was proposed and confirmed. • Fresh kitchen waste with original moisture was used for HTC process. • Synergistic promotion effect mainly occurred in coke co-gasification stage. • Process water contained 785.82 mg/L of K, catalyzing the coke co-gasification. Kitchen waste has high moisture and rich organics, which can be transformed into hydrochar by hydrothermal carbonization (HTC) and then used for gasification efficiently. But process water (liquid product from HTC, containing organic compounds) has not been well utilized in the way of thermochemistry. In this study, a scheme of co-gasification of solid and liquid products of kitchen waste HTC process was proposed, and the separate gasification and co-gasification were studied. The results showed that after HTC process, the obtained hydrochar size became smaller and uniform, and the high heating value increased from 19.90 MJ/kg to 28.03 MJ/kg. The carbon skeleton of hydrochar was mainly composed of aromatic and alkyl C, which was easily converted into coke during gasification. Process water mainly contained pyrazine organics, and its C and N content were 18.94 g/L and 3.25 g/L, respectively. The co-gasification syngas yield of solid and liquid products was significantly higher than the calculated total yield of separate gasification. There was obvious synergistic effect in the coke co-gasification stage, and the H 2 production was 1.24 times of the calculated value. Synergistic effect was mainly caused by the introduction of process water, which contained 785.82 mg/L of K and would catalyze the coke co-gasification. HTC coupled with co-gasification is an efficient disposal for kitchen waste with high moisture. [ABSTRACT FROM AUTHOR]

Over the past decades, water pollution caused by organic dyes has attracted extensive attention. The development of efficient, environmental friendly photocatalysts is a promising route for wastewater purification. Herein, a novel wild jujube shell derived biochar/g-C 3 N 4 (BC/CN) composite has been prepared via a one-step calcination route. Although the specific surface area (9.37 m2/g) and pore size (14.57) of the BC/CN composite are smaller than those of g-C 3 N 4 , it exhibits enhanced photocatalytic activity. Especially, the 0.25-BC/CN composite (sour jujube shell powder/melamine ratio = 0.25) displays excellent photocatalytic activity, and can degrade ∼97.1 % of RhB under 40 min light irradiation, which is ∼46.51 times to that of pure g-C 3 N 4. The actives species of h+, ·OH, ·O 2 − and 1O 2 active species play the important roles in the photocatalytic system of the BC/CN composite. The results mechanistic study demonstrates that the enhanced photocatalytic activity of the BC/CN composite can be mainly attributed to the improved light absorption and charge separation efficiency of the catalyst. This work provides a simple method for preparing of novel highly efficient g–C 3 N 4 –based photocatalyts for wastewater purification, and provides a new idea for the recycling, and high-value utilization of the organic solid waste from traditional Chinese medicine. [Display omitted] • A novel biochar/g-C 3 N 4 composite is succuessfully fabricated. • 0.25-BC/CN composite can degrade 97.1 % rhodamine B within 40 min treatment. • Enhanced removal rate of RhB can be ascribed to the effect of adsorption-photocatalytic. • Charge separation efficiency of g-C 3 N 4 was significantly improved by the biochar. • The effect factors, active species, intermediates and mechanism were studied. [ABSTRACT FROM AUTHOR]