Search Results (142)

Composting represents a sustainable and effective strategy for converting organic waste into nutrient-rich soil amendments, providing a safer alternative to raw manure, which poses significant risks of soil, crop, and water contamination through pathogenic microorganisms. This study, conducted under semi-arid Moroccan conditions, investigated the efficiency of co-composting green garden waste with sheep manure in an open window system, with the objective of assessing pathogen inactivation and evaluating compost quality. The process, conducted over 120 days, maintained thermophilic temperatures exceeding 55 °C, effectively reducing key pathogens including Escherichia coli, total coliforms, Staphylococcus aureus, and sulfite-reducing Clostridia (SRC), while Salmonella was not detected throughout the composting period. Pathogen reductions exceeded 3.52-log despite moderate temperature fluctuations, indicating that additional sanitization mechanisms beyond heat contributed to inactivation. Compost quality, assessed using the CQI, classified Heap 2 (fallen leaves + sheep manure) as good quality (4.06) and Heap 1 (green waste + sheep manure) as moderate quality (2.47), corresponding to differences in microbial dynamics and compost stability. These findings demonstrate that open windrow co-composting is a practical, low-cost, and effective method for safe organic waste management. It supports sustainable agriculture by improving soil health, minimizing environmental and public health risks, and providing guidance for optimizing composting protocols to meet regulatory safety standards. Full article

Spent mushroom substrate (SMS) is an excellent conditioner for livestock manure composting. However, existing studies have confirmed that it is difficult to achieve the desired effect by directly mixing SMS with manure. Coarse (≥2 mm) and fine (<2 mm) of SMS particles from an edible fungus (Auricularia auricula) were obtained after sieving and used for cow manure composting. In our study, the appropriate ratio of coarse SMS to fine SMS particles added to the manure was explored. Four treatments were designed, adding 20% coarse SMS (T1), 15% coarse SMS + 5% fine SMS (T2), 5% coarse SMS + 15% fine SMS (T3), and 20% fine SMS (T4) to cow manure for composting, respectively. The physicochemical properties, maturity, and nutrient content of the composts were analyzed in a 35-day composting trial. The optimal treatment was determined through a comprehensive evaluation using the entropy-weighted TOPSIS method. The results showed that the highest composting temperature reached 65.13 °C in T3, and the duration of the thermophilic phase of T2 was the longest. The relative germination rate was not affected, and the relative radicle growth (RRG) reflected the variation in phytotoxicity during composting. After composting, the pH of the finished composts was between 8.78 and 9.05. The electric conductivity was between 2207 and 2513 μS cm⁻¹. The ammonium nitrogen content was less than 150 mg kg⁻¹, which was at the level found in mature compost. The RRG was no less than 80%, indicating the compost was mature and had no phytotoxicity. The available phosphorus and potassium contents increased by 4.8% to 59.1% compared with that before composting. The comprehensive evaluation showed that the treatment supplemented with 15% coarse SMS and 5% fine SMS was optimal. Full article

This study investigated the effects of different Effective Microorganism (EM) inoculation concentrations (0%, 0.5%, 2%, 5%, 10%, 15%) on the co-composting of Auricularia heimuer residue with chicken manure and the subsequent growth of maize. The aim was to enhance composting efficiency and promote maize productivity. Results showed that EM addition, particularly at medium concentrations, significantly accelerated the composting process by shortening the heating phase and prolonging the thermophilic period, with the 10% treatment reaching >50 °C by day 2. The 5–10% EM treatments markedly promoted the degradation of cellulose and hemicellulose, and enhanced key enzyme activities (e.g., cellulase and hemicellulase) during composting and maize growth stages. Regarding soil nutrients, the 5% EM treatment led to the most balanced increases in total nitrogen (TN), total phosphorus (TP), and total potassium (TK) contents, with rises of 58.7%, 47.8%, and 130.4%, respectively, during the seedling stage. For maize yield, this treatment enhanced total grain weight, hundred-grain weight, and root activity by 25.7%, 30.9%, and 53.2%, respectively, while also increasing dry matter and root weight. Redundancy and correlation analyses indicated strong positive relationships among root activity, soil TN, cellulase activity, and final yield. In conclusion, EM inoculation at 5–10% optimizes the composting process, improves substrate quality and nutrient supply, and promotes maize root development and yield, with 5% EM offering the most comprehensive benefits. This study provides a practical approach for agricultural waste recycling and sustainable maize cultivation. Full article

To mitigate the environmental burden of sugar industry filter mud in Guangxi and unlock its resource potential, this study introduces a novel approach leveraging the unique microbial resources of mangrove ecosystems to enhance composting efficiency. Microbial strains were isolated from rhizosphere sediments of mangroves in the Beilun River in Fangchenggang and inoculated into a composting system using sugar filter mud. The results demonstrated that inoculation with a mangrove-derived microbial consortium—represented by the nitrogen-fixing strain P1N2—significantly accelerated and prolonged the thermophilic phase (≥53.6 °C for 12 days), leading to greater organic matter degradation and a reduced carbon-to-nitrogen ratio (C/N = 15.2). High-throughput sequencing revealed distinct microbial succession patterns during composting. It confirmed that the exogenous inoculant reshaped the indigenous microbial community, promoting the dominance of functional taxa, including Ochrobactrum, Bacillus, and Nocardiopsis, at key stages, thereby facilitating efficient humus synthesis. Pot experiments further verified that the resulting compost improved soil structure, stabilized nutrient availability, and markedly increased the yield and quality of Chinese flowering cabbage (Brassica parachinensis). These findings demonstrate that mangrove-derived microbial inoculants serve as potent bio-enhancers, providing an environmentally sustainable and technically feasible pathway for the high-value reutilization of sugar industry filter mud. Full article

Livestock manure is a major source of environmental pollution and greenhouse gas emissions if improperly managed. Aerobic composting represents a sustainable approach to manure recycling that can stabilize organic matter, mitigate carbon loss, and recover nutrients for agricultural use. In this study, sheep manure was mixed with sawdust to optimize the carbon-to-nitrogen (C/N) ratio and enhance aeration, and the mixture was subjected to aerobic composting with a cellulose-degrading microbial inoculant. To rigorously evaluate the biological effects, a control treated with sterilized inoculant was included to eliminate nutrient inputs from the carrier matrix. The inoculant significantly improved composting performance by extending the thermophilic phase by five days and reducing the C/N ratio to 19.8 on day 32, thereby shortening the composting cycle. Moreover, microbial inoculation enhanced nutrient retention, resulting in a 20.14% increase in total nutrient content, while the germination index (GI) reached 89.75%, indicating high compost maturity and reduced phytotoxicity. Microbial community analysis revealed that cellulose-degrading inoculants significantly altered microbial richness and diversity and accelerated community succession. Redundancy analysis (RDA) and hierarchical partitioning analysis showed that total organic carbon (TOC) and GI were the main environmental drivers of bacterial community dynamics, whereas pH and GI primarily regulated fungal community succession. These findings suggest a strong link between compost maturity and microbial community restructuring. This study demonstrates that cellulose-degrading microbial inoculation accelerates the composting of sheep manure, enhances organic matter degradation, and improves fertilizer efficiency while reducing the phytotoxicity of the final product. Full article

Direct agricultural use of digestate from food waste is hindered by its high phytotoxicity, and the addition of common auxiliary materials during composting increases the project cost. In this study, mature compost (MC) was used to replace part of mushroom residue as auxiliary materials for controlled experiments at a pilot-scale horizontal double-layer mechanical composting device. The results showed that the MC addition heated up more rapidly than the control group (NC), peaking at 72 °C on day 5. The moisture content was reduced from 47.17% to 25.36%, which was lower than the final value of 28.48% in the NC. The final humic acid (HA) content in the MC group (60.88 g/kg) was higher than that in the NC (44.82 g/kg). The seed germination index (GI) for both groups exceeded 70%, meeting the national standard. The MC group achieved a final GI of 119.37%, which was significantly higher than that of the NC (81.29%). The phylum Firmicutes became the dominant group in the MC group during the thermophilic phase, demonstrating strong thermotolerance and a high capacity for degrading recalcitrant organic compounds such as cellulose. At the genus level, Bacillus demonstrated a relatively high abundance during the thermophilic phase. These findings imply that the MC addition improves the composting property, enhances the degree of humification, and shortens the composting time, providing technical support for the improvement of aerobic composting of food waste digestate, thus contributing to more sustainable waste management by promoting a circular economy and reducing reliance on external inputs. Full article

Inefficient chromium (III)–collagen cross-linking during leather tanning generates solid waste and effluents containing residual chromium, raising environmental and health concerns. Biological strategies are increasingly popular for tannery waste treatment, but the microbial communities involved in leather degradation remain poorly understood. This study did not seek to evaluate leather disintegration according to standardised compostability criteria, but to establish a thermophilic composting system suitable for characterising leather-associated microbial communities, biofilm formation on leather and isolating cultivable strains. Composting assays were carried out at two scales, in which wet blue leather was mixed with organic compost under self-heating thermophilic conditions. Temperature was monitored, and mass loss and changes in leather structure were determined by gravimetry and scanning electron microscopy. Bacterial and fungal communities in compost with and without leather were analysed using high-throughput amplicon sequencing. Thermophilic consortia dominated by Firmicutes, Actinobacteria and Ascomycota were established, and several bacterial isolates and a filamentous fungus were recovered. Together, these results provide a first basis for understanding the communities and strains associated with chromium-tanned leather during thermophilic composting, supporting future searches for microorganisms and enzymes of interest for biological strategies to manage chromium-tanned leather waste. Full article

Humus is the core product and key indicator of compost maturity. How to improve the humus content and accelerate its formation in composting is critical for the improvement of compost quality. This study investigated the effects of adding compost derived from different stages including thermophilic, cooling, and maturation phases on compost initiation and efficiency in terms of humus formation and microbial community dynamics. The results reveal that adding compost from the cooling stage markedly outperforms the thermophilic and maturation phases, achieving a germination index of 107.22%, a carbon-to-nitrogen ratio of 15.95, a humus content of 91.12 g/kg, a humic acid concentration of 71.49 g/kg, and a polymerization degree of 3.64. EEMs indicated that the cooling-phase additive increased humic-like fluorescence (Region V) at day 35. The abundance and diversity of humifying bacteria were significantly enriched, and the succession of microbial community was accelerated as confirmed by redundancy analysis. This approach also improved compost quality and reduced the overall composting duration, thus suggesting that using compost from the cooling phase as an additive is an effective way to increase the humus content and accelerate the humification, providing a green solution for organic waste recycling and sustainable agricultural development and production. Full article

Increasing concerns about environmental issues have recently intensified the search for sustainable alternatives to conventional plastics that minimize ecological impacts. This study evaluates the biodegradability, compostability, and ecotoxicity of a PLA-based biocomposite containing 30–40% micronized cellulose fibers. The material complied with the European limits for fluorine and heavy metals. Biodegradability was assessed through a respirometric test under thermophilic conditions, achieving 81% degradation in 155 days. Thermophilic compostability was evaluated by monitoring the disintegration of injected products made from the biocomposite pellets and cut into pieces with thicknesses of 1.0 mm and 2.1 mm, revealing that increased specific surface area prolongs composting time. Ecotoxicity was tested through seed germination and plant growth assays on barley, onion, sunflower, tomato, and wheat using the biocomposite mature compost mixed (25% and 50%) with a TÜV Austria certified soil. Results showed species-dependent effects: sunflower germination was enhanced, while other plants experienced slight growth delays. No severe phytotoxicity was observed, except for barley and wheat. Despite the proven biodegradability and compostability, the biocomposite product’s dimensions influence disintegration and decomposition rates. Furthermore, compost applications may have variable effects on plant development. These findings improved knowledge about sustainable materials performance, raising awareness about more responsible design, consumption, and disposal strategies. Full article

This study focused on the effect of electric field intensity on carbon transformation in aerobic composting of biochar–pig manure. Four treatment groups were set up with voltages of 0 V (CK group), 2 V (L group), 4 V (M group), and 5 V (H group). The physicochemical properties and carbon forms of the compost were characterized, and how they influence composting was investigated by observing the changes in the functional groups of the compost and the interactions between microorganisms and environmental factors. The results showed that the electric field treatment groups entered the thermophilic phase 2–3 d earlier than the CK group, and the duration of this phase was extended by 3–5 d. The seed germination indices were 95.2%, 106%, 110%, and 121% for the CK, L, M, and H treatment groups, respectively. The DOC content decreased by 11.7%, 11.4%, 16%, and 16.5%. The degradation rates of hemicellulose were 38.6%, 41.1%, 42.7%, and 42.8%, respectively. Those of cellulose were 46.8%, 47.7%, 51.8%, and 54.5%, respectively. Those of lignin were 37.2%, 40.8%, 47.9%, and 53.3%, respectively. Compared to the CK group, the cumulative emissions of CO₂ and CH₄ in the L, M, and H groups were reduced by 13.8–25% and 47.86–75.76%, respectively, resulting in lower carbon losses. Fourier transform infrared spectroscopy indicated that applying an external electric field induces changes in the functional groups of humic acid, the formation of aromatic functional groups, and the optimization of the maturation process. Compared to the CK group, applying an electric field (L/M/H groups) optimized the microbial communities (especially the Bacteroidota, Chloroflexi, and Acidobacteriota abundances), enriched Proteobacteria and Myxococcota, and regulated the moisture content and C/N ratio. These changes in the electric field treatment groups significantly improved the degradation efficiency of cellulose, lignin, and hemicellulose and reduced greenhouse gas emissions. Full article

The proliferation of antibiotic resistance genes (ARGs) in livestock manure has raised growing environmental and public health concerns. Composting is widely recognized as an effective method to mitigate ARG dissemination; however, recent studies have increasingly reported a rebound in ARG abundance during the curing stage of composting, undermining its long-term effectiveness. Here, “rebound” refers to a renewed increase in ARG abundance—either in absolute terms or relative to the 16S rRNA gene—following its decline to a minimum during the thermophilic phase. This review systematically summarizes the dynamic changes in ARGs throughout the composting process, with a particular focus on the mechanisms and drivers underlying ARG rebound. Vertical and horizontal gene transfer, along with microbial succession, are discussed as key contributors to this phenomenon. Current strategies to suppress ARG rebound, including microbial community manipulation, hyperthermophilic composting, and exogenous amendments, are evaluated. Furthermore, the roles of heavy metals and extracellular polymeric substances in promoting ARG persistence are examined, highlighting their potential involvement in ARG rebound. This review aims to provide a comprehensive understanding of ARG rebound in composting and to inform the development of more effective, integrated mitigation strategies. Full article

The composting of organic waste is a sustainable strategy for waste management and soil fertility improvement. However, the composting process is often associated with greenhouse gas (GHG) emissions, having a negative impact on the environment. This study investigated the effects of BC pyrolysis temperature (300 °C, 600 °C) and application rate (5% and 10%) on GHG emissions during the thermophilic phase and compost quality. The experimental treatments were a control and four BC treatments varying in pyrolysis temperature (300 °C, 600 °C) and application rate (5%, 10%). As a result, BC pyrolyzed at 600 °C and added at 10% (T2R2) resulted in the highest thermophilic temperature (63.5 ± 0.5 °C). This treatment significantly achieved substantial reductions in NH₃, N₂O, CH₄, and CO₂ emissions by 55 ± 2.7%, 50 ± 2.7%, 88 ± 4.2%, and 23 ± 2.3%, respectively, relative to the control. Compost quality was enhanced notably, with dry matter increasing to 46.4 ± 0.11% (T2R1), organic matter reaching 30.9 ± 0.05% in T2R1, and total nitrogen peaking at 0.8 ± 0.001% (T1R2). The C:N ratio decreased from 27:1 in the control to 21:1 in the treatment of T1R2, indicating an accelerated composting process. The NH₄-N levels were the highest in T1R2 and T2R2 (659 ± 0.1 and 416 ± 0.2 mg kg⁻¹), while EC increased to 9.5 ± 0.006 ms/cm (T2R1), and bulk density decreased to 410 ± 0.08 kg/m³ (T1R1). These results demonstrate that high-temperature biochar, especially at a rate of 10%, is effective in reducing emissions and improving compost quality. Future research should explore long-term effects and microbial mechanisms to optimize biochar use in composting systems. Full article

Although bacterial and fungal communities play essential roles in organic matter degradation and humification during composting, their composition, interactions, abiotic compost properties, and succession patterns remain unclear. In this study, the succession of bacterial and fungal communities during algal sludge composting was explored using 16S and ITS rRNA amplicon sequencing. The compost rapidly entered the thermophilic phase (>50 °C) within the first phase. During the composting process, the diversity of bacterial and fungal communities did not show a significant response to the different composting phases. The physicochemical parameters and microbial community structures changed significantly during the thermophilic and cooling phases, particularly in the former, and gradually stabilized as the compost matured. Integrated random forest and network analyses suggested that the bacteria genera Geobacillus and Parapedobacter, along with the fungus genus Gilmaniella, could serve as potential biomarkers for different composting phases. The functional activity of the bacterial communities was obviously higher during the thermophilic phase than during the other phases, while fungal activity remained relatively high during both the thermophilic and cooling phases. Structural Equation Modeling (SEM) further indicated that bacterial communities primarily mediated nitrogen transformation and humification processes, while fungal communities mainly contributed to humification. These results cast a new light on understanding about microbial function during aerobic algal sludge composting. Full article

In this study, the effects of composting phase and bulking agent on macronutrient extraction and the chemical, physicochemical, and biological properties of 20 compost teas from poultry waste composting mixtures were evaluated. Phosphorus (P) extraction was more efficient during stabilization after the thermophilic phase; however, water-soluble P declined as composting progressed. K was more amenable to extraction, with yields ranging from 30% to 70%, followed by N (2% to 12%) and P (1% to 7%). Compost tea quality was clearly affected by both the bulking agent and the composting stage. Bulking agents that accelerate the process, such as cotton waste (CW) and Napier grass (NG), contributed to nutrient mineralization, increasing availability in the compost tea but also raising salt contents responsible for phytotoxicity. In contrast, tree trimmings (TT), sawdust (S), and sugarcane bagasse (SCB) showed better results, striking a balance between nutrient availability and salt content. The period between the thermophilic phase and cooling was the most suitable for extraction, providing the greatest contribution of water-soluble nutrients. This study highlights the influence of bulking agents and composting phases on nutrient extraction and phytotoxicity of compost teas and provides new insights into the role of electrical conductivity as a threshold indicator for safe agricultural application. Full article

With the rapid expansion of urban green spaces and the increasing amount of domestic waste, efficient and sustainable treatment of green waste (GW) and kitchen waste (KW) has become a pressing issue. Co-composting offers a green and low-carbon solution, yet a systematic understanding of its greenhouse gas (GHG) emission dynamics remains lacking. This study aims to investigate the impact of varying GW:KW ratios on GHG emissions during composting, in order to identify optimal mixing strategies and sup-port the development of low-carbon urban waste management systems. Six treatments with different GW:KW ratios (10:0, 9:1, 8:2, 7:3, 6:4, and 5:5) were evaluated under continuous aeration for 42 days. Results showed: (1) All treatments exhibited a typical composting temperature profile (mesophilic, thermophilic, cooling, maturation), with final seed germination index (GI) > 95% and significantly reduced E4/E6 ratios, indicating maturity. (2) When kitchen waste (KW) was ≤20%, cumulative GHG emissions slightly increased; KW ≥ 30% led to net reductions, with the 6:4 treatment (A4) achieving the highest decrease (17.44%) in total CO₂-equivalent emissions. In conclusion, maintaining KW at 40–50% optimally balances compost maturity and emission reduction, providing a viable strategy for the high-value utilization of urban organic waste and carbon mitigation. Full article