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Aerobic composting technology is an efficient, safe and practical method to reduce the residues of antibiotics and antibiotic resistance genes (ARGs) due to unreasonable disposal of livestock manure. Nowadays, it remains unclear how aerobic composting works to minimize the level of remaining antibiotics and ARGs in manure. Moreover, aerobic composting techniques even have the potential to enhance ARGs level. Therefore, this study conducted a literature review on ARGs variation during the composting process to assess the fate, migration, and risk features of antibiotics and ARGs in different livestock manure and compost. The relationship between ARGs reduction and crucial factors (temperature, heavy metal, and microbial community structures) in the composting process was discussed. The merits and limitations of different technologies used in compost was summarized. The effects on ARGs reduction in the aerobic composting process with various strategies was examined. We attempt to provide a fresh and novel viewpoint on the advancement of global aerobic composting technology., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

China, being a major agricultural nation, employs aerobic composting as an efficient approach to handle agricultural solid waste. Nevertheless, the composting process is often accompanied by greenhouse gas emissions, which are known contributors to global warming. Therefore, it is urgent to control the formation and emission of greenhouse gases from composting. This study provides a comprehensive analysis of the mechanisms underlying the production of nitrous oxide, methane, and carbon dioxide during the composting process of agricultural wastes. Additionally, it proposes an overview of the variables that affect greenhouse gas emissions, including the types of agricultural wastes (straw, livestock manure), the specifications for compost (pile size, aeration). The key factors of greenhouse gas emissions during composting process like physicochemical parameters, additives, and specific composting techniques (reuse of mature compost products, ultra-high-temperature composting, and electric-field-assisted composting) are summarized. Finally, it suggests directions and perspectives for future research. This study establishes a theoretical foundation for achieving carbon neutrality and promoting environmentally-friendly composting practices., Competing Interests: Declaration of competing interest The authors declare that they do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2024. Published by Elsevier Ltd.)

Nitrous oxide (N 2 O) production is associated with ammonia-oxidizing bacteria (amoA-AOB) and denitrifying fungi (nirK-fungi) during the incorporation of biochar and biogas residue composting. This research examined the relative contribution of alterations in the abundance, diversity and structure of amoA-AOB and nirK-fungi communities on N 2 O emission by real-time PCR and sequence processing. Results showed that N 2 O emissions showed an extreme relation with the abundance of amoA-AOB (rs = 0.584) while giving credit to nirK-fungi (rs = 0.500). Nitrosomonas and Nitrosospira emerged as the dominant genera driving ammoxidation process. Biogas residue changed the community structure of AOB by altering Nitrosomonadaceae proportion and physiological capacity. The denitrification process, primarily governed by nirK-fungi, served as a crucial pathway for N 2 O production, unveiling the pivotal mechanism of biochar to suppress N 2 O emissions. C/N and NH 4 + -N were identified as significant parameters influencing the distribution of nirK-fungi, especially Micromonospora, Halomonas and Mesorhizobium., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

This research investigated biogas residue and biochar addition on antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and changes in bacterial community during agricultural waste composting. Sequencing technique investigated bacterial community structure and ARGs, MGEs changes. Correlations among physicochemical factors, ARGs, MGEs, and bacterial community structure were determined using redundancy analysis. Results confirmed that biochar and biogas residue amendments effectively lowered the contents of ARGs and MGEs. The main ARGs detected was sul1. Proteobacteria and Firmicutes were the main host bacteria strongly associated with the dissemination of ARGs. The dynamic characteristics of the bacterial community were strongly correlated with pile temperature and pH (P < 0.05). Redundancy and network analysis revealed that nitrate, intI1, and Firmicutes mainly affected the in ARGs changes. Therefore, regulating these key variables would effectively suppress the ARGs spread and risk of compost use., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling functional genes and bacterial and fungal communities during composting with biochar and biogas residue amendments were studied. Correlations between microbial community structure, functional genes and physicochemical properties were investigated by network analysis and redundancy analysis. It was shown that the gene of acsA abundance accounted for about 50% of the C-related genes. Biogas residue significantly decreased the abundance of denitrification gene nirK. Biogas residues can better promote the diversity of bacteria and fungi during composting. Biochar significantly increased the abundance of Humicola. Redundancy analysis indicated that pile temperature, pH, EC were the main physicochemical factors affecting the microbial community. WSC and NO 3 -N have significant correlation with C, N, P, S functional genes. The research provides a theoretical basis for clarifying the metabolic characteristics of microbial communities during composting and for the application of biochar and biogas residues in composting.- -N have significant correlation with C, N, P, S functional genes. The research provides a theoretical basis for clarifying the metabolic characteristics of microbial communities during composting and for the application of biochar and biogas residues in composting., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study examined the effects of biochar, biogas residue, and their combined amendments on CO 2 and CH 4 emission, enzyme activity, and related functional genes during rice straw composting. Results showed that the biogas residue increased CO 2 and CH 4 emissions by 13.07 % and 74.65 %, while biochar had more obvious inhibition. Biogas residue addition enhanced functional gene abundance more than biochar. Biogas residue raised the methanogens mcrA gene by 2.5 times. Biochar improved the Acetyl-CoA synthase and β-glucosidase activities related to carbon fixation and decreased coenzyme activities related to methanogens. Biochar and biogas residue combined amendments enhanced the acsB gene abundance for CO 2 assimilation process and decreased methyl-coenzyme M reductase α subunit activity. Pearson correlation analysis indicated that organic matter was the significant variable affecting CO 2 and CH 4 emissions (P < 0.01). These results indicated biochar played significant roles in carbon loss and greenhouse emissions caused by biogas residue incorporation during composting., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Due to the increasing global severe soil pollution, a large number of heavy metal elements are enriched in biomass grown in polluted areas and hyperaccumulators used for phytoremediation. Disposing of above contaminated biomass through traditional in-situ combustion, return to the field, and composting strategies can result in heavy metals re-entering the environment and causing secondary pollution, which poses a huge challenge to the safe disposal of waste biomass. Pursuing more efficient strategies is necessary to achieve green, clean utilization of contaminated biomass and enhance the value. Retaining heavy metals in biomass serves them as functional materials through effective measures can be a sustainable idea. This review described the characteristics of widely used traditional biomass disposal strategies and discussed commonly used thermochemical technologies for heavy metal immobilization. The progress and application status of value-added materials such as chemicals, soil additives, catalysts, absorbents, capacitors, and antibacterial materials prepared from contaminated biomass were systematic overviewed, and the future development direction was prospected. It can be emphasized from the study that the conversion of contaminated biomass into high-value materials is significant and provides a new idea for the green treatment of contaminated biomass and are beneficial to the improvement of phytoremediation technology. Contaminated biomass deserves further exploration and attention as a resource with infinite potential. [Display omitted] • Thermochemical technology can effectively immobilize heavy metals in biochar. • Metals in contaminated biomass serve as active components and loading sources. • Contaminated biomass can convert to environmentally functional materials. • Recycling and valorization of contaminated biomass is a win-win strategy. [ABSTRACT FROM AUTHOR]

Red mud and compost are two inexpensive and effective materials available for the in situ treatment of soil contaminated with heavy metals. In order to investigate the specific process involved, a detailed analysis of the synergistic effects of combined red mud and compost was carried out. The efficiency of three different treatment systems, namely compost (C), red mud (R), and a mixture of compost and red mud (R + C), on the movability, ecological risk, and biological effective Cu, Zn, Cd, and Pb over time of incubation in agricultural soil was evaluated. Results showed that the pH, water extractable organic carbon (WEOC) and total organic carbon (TOC) showed significant changes after addition of these amendment materials to the target soil. The combination of red mud and compost mixture as amendment material (R + C) resulted in the largest reduction in efficiency of the available heavy metals. In addition, the microbial biomass in the treated soil increased after addition of the amendment materials, highest increase was observed with R + C. The results indicate that these amendment materials, especially R + C could lower the ecological risk of heavy metals in soil. [ABSTRACT FROM AUTHOR]