Food waste anaerobic digestion is susceptible to acidification, and its treatment process encompasses a wide concentration range, from wet to dry. To investigate the enhancement efficiency and mechanism of ethanol pre-fermentation (EP) at varying total solids (TS) concentrations, this study systematically compared its performance in wet (TS 5%), semi-dry (TS 15%), and dry (TS 20%) systems. The results indicate that the enhancement efficiency and mechanism of EP are highly dependent on the TS concentration. In the semi-dry system with TS 15%, EP significantly increased methane production by 1514%, successfully restoring stability to a system on the brink of failure. Mechanistic studies reveal fundamental differences in EP's mode of action: at low solid concentrations (TS 5%), stability improvement primarily arises from fermentation pathway optimization and favorable mass transfer conditions; at higher solid concentrations (TS 15% and 20%), all physicochemical data, thermodynamic analysis, and shifts in microbial communities support a plausible hypothesis: the electroactive functional microbes enriched (e.g., Petrimonas, Syntrophomonas, and Methanosarcina) by EP may have activated the direct interspecies electron transfer (DIET) pathway, effectively overcoming mass transfer limitations through an efficient syntrophic network. This study reveals for the first time that solid concentration is the key parameter determining the enhancement mechanism of EP, challenging the conventional understanding of its universal mode of action. It provides a new theoretical framework for precisely enhancing the digestion processes of organic waste with varying solid concentrations.

Anaerobic digestion (AD) is widely applied for its ability to convert organic waste into bioenergy, which helps to optimize the energy structure. However, ammonia inhibition, which is frequently associated with process instability in biogas plants, has significantly limited AD applications. Existing reviews have explored ammonia inhibition from various perspectives but have primarily focused on the methanogenesis process. By contrast,​ the contribution of impaired acetogenesis function to ammonia-induced inhibition has been largely overlooked. This review integrates molecular biological evidence to demonstrate that acetogenesis serves as the key link affecting ammonia-inhibited reactor performance, with a particular focus on the effects of ammonia stress on the dynamic succession, energy harvest, and enzymatic activities involved in acetogenesis. The impaired energy harvest and downregulation of enzymatic activities have been identified as the primary causes of the irreversible ammonia inhibition of acetogens, which then leads to the failure of the acetogenesis process, volatile fatty acid accumulation, and ultimately the irreversible deterioration of reactor performance. Furthermore, building on this new mechanistic insight, this review re-evaluates the efficiency and limitations of ammonia inhibition mitigation strategies. Future efforts should focus on developing innovative multi-data integration analysis strategies—such as combining activated cell sorting with targeted metaproteomics, and stable isotope probing with metabolomics—to overcome current methodological challenges in analyzing​ ammonia inhibition mechanism. These insights provide a new perspective on the ammonia inhibition mechanism and important guidance for the stable operation of fermentation systems.

The large-scale utilization of lithium slag (LS) is constrained by a dosage bottleneck induced by its high intrinsic crystallization energy barrier and sluggish early-age reaction kinetics. This study innovatively develops a low-carbon alkali-activated ternary cementitious system comprising LS, ground granulated blast furnace slag (GGBFS), and steel slag (SS), with a fixed LS dosage of 60 wt%. Integrating multi-scale characterization with hydration kinetics, the cross-age synergistic activation mechanism of multiphase solid wastes is systematically decoupled. Results demonstrate that the preferential depolymerization of highly reactive GGBFS constructs the initial C-(A)-S-H gel network, compensating for the early-age dilution effect of massive LS. Subsequently, the controlled hydration of SS exhibits an ion slow-release effect, which is phenomenologically inferred to drive a deep secondary alkaline etching on the LS skeleton. This restructures the low-polymerization aluminosilicate network into a highly cross-linked state. Coupled with the in-situ coprecipitation of micro-expansive ettringite, which is synergistically driven by the SS-supplied calcium and the inherent sulfates released from LS, the system builds a hierarchical interlocking skeleton with a high spatial fractal dimension, refining capillary pores down to the gel-pore level (< 10 nm). Furthermore, cradle-to-gate life cycle assessment (LCA) confirms the optimal system achieves a 28-day compressive strength nearing 50 MPa while reducing global warming potential (GWP) and fossil fuel depletion (FFD) by over 64% on a per-unit-mass basis compared to ordinary Portland cement (OPC). These findings provide a viable strategy for the large-scale safe and sustainable utilization of bulk LS.

This study investigated how ethanol pretreatment (EP) enhances the resilience of high-solid anaerobic digestion against rapid organic loading shocks. Semi-continuous reactors fed with either untreated or EP-treated food waste were compared, and the underlying mechanisms were elucidated by integrating thermodynamic calculations with metagenomic analyses. At an organic loading rate of 6.0 g VS/(Lˑd), the control group (untreated) collapsed due to the accumulation of propionate and other longer-chain volatile fatty acids (VFAs), resulting in a methane yield decrease exceeding 70%. In contrast, the EP group maintained stability, exhibiting a methane yield decrease of less than 5%, with VFAs dominated by readily degradable acetate. Thermodynamic analysis confirmed that EP significantly lowered the energy barriers for VFA degradation. Metagenomic analysis revealed that both propionate/butyrate activation pathways (with lower energy cost or independence from acetyl-CoA) and syntrophic acetate oxidation were activated in the EP group, thereby avoiding the VFA metabolic stress observed in the control group. Furthermore, higher abundances of conductive type IV pili genes, Complex II, and archaeal V/A-type ATPase were detected in the EP group, suggesting the establishment of direct interspecies electron transfer and enhanced electron flux and energy capture efficiency. Moreover, under high loading conditions, only a few high-abundance metagenome-assembled genomes (MAGs) were detected in the control group, while multiple MAGs carrying identical VFA-degrading enzyme systems were identified in the EP group. The functionally redundant microbiota, unobstructed VFA metabolic pathways, and efficient electron transfer and energy supply collectively sustained the stability of the EP group under loading shocks.

Foaming poses a significant threat to the stability of food waste anaerobic digestion (AD) systems. This study elucidates the regulatory mechanisms of quorum sensing (QS) underlying foaming by integrating multi-omics tracking and quorum quenching verification methodologies. The results indicate that an increased organic loading rate leads to the proliferation of core microorganisms (MAG25, MAG57, MAG153) and upregulates QSrelated genes (hdtS, RpfB, DAC, DGC), which drives the accumulation of short-chain acyl-homoserine lactones (AHLs) (C4/C6/C8-HSL), diffusible signal factor (DSF), and cyclic di-nucleotides (c-di-AMP/c-di-GMP), thereby activating the QS network. This network triggers foaming events by activating the transcription factor bapA, coordinating the complete protein (PN) metabolic cascade, and secreting excessive PN in extracellular polymeric substances (EPS), with an increase of 31 % to 1914 +/- 28 mg/L within 5 days. Additionally, vanillin (100 mg/L) was found to concurrently quench signaling molecules, reduce EPS-PN accumulation, decrease foaming, and maintain methane production, thereby confirming the causal relationship between QS and foaming. This study provides the first direct evidence of c-di-AMP in AD foaming and indicates that the QS network (core signals: short-chain AHLs/DSF/c-di-AMP/c-di-GMP) drives the excessive synthesis of EPS-PN as the core mechanism of foaming, offering theoretical support for foam control based on quorum quenching.

Biogas produced by conventional anaerobic digestion (AD) requires upgrading due to its elevated CO2 content. The microbial electrolysis cell coupled with anaerobic digestion (MEC-AD) facilitates in-situ biogas upgrading by enhancing microbial metabolism through bioelectrochemical processes. However, the performance of MEC-AD in treating real organic wastes is often constrained by challenges such as complex electron flow competition, mass transfer limitations, and instability within the microbial ecosystem. This review begins by elucidating the mechanisms through which MEC-AD achieves CO2 reduction and methane enrichment, primarily via hydrogenotrophic methanogenesis and direct electromethanogenesis. It then critically examines the performance gaps and underlying causes of these limitations when transitioning from ideal substrates to real waste streams. To address these challenges, the paper systematically evaluates three synergistic enhancement strategies: optimizing electrode systems to improve electron transfer, manipulating microbial syntrophic networks to enhance electron utilization, and precisely controlling operational parameters to direct electron flow. Finally, future research directions are proposed, emphasizing the necessity for cross-scale precise regulation of electron transfer, intelligent reactor design, and comprehensive assessments of energy efficiency to facilitate the engineering application and carbon reduction potential of MEC-AD technology.

Ammonia inhibition represents a significant bottleneck that constrains the stability and efficiency of anaerobic digestion (AD) processes, particularly for high-nitrogen organic waste. This review synthesizes multi-scale evidence to illustrate that while elevated ammonia levels can alter the overall microbial community structure, process failure is most directly linked to its profound inhibition of two thermodynamically constrained, low-redundancy metabolic steps: syntrophic propionate oxidation and acetoclastic methanogenesis. This selective vulnerability is fundamentally linked to the mechanism by which ammonia stress interferes with core cellular functions related to transcription and translation. To address this bottleneck, existing mitigation strategies can be categorized into those aimed at overcoming ammonia inhibition or those focused on ammonia removal. The former, which includes additive application and bioaugmentation, can alleviate ammonia stress in the short term and may further facilitate the acclimation of microbial communities, thereby supporting relatively stable operations under high-ammonia conditions. However, challenges related to cost, operational complexity, and long-term stability persist. Alternatively, ammonia removal strategies, such as iron-mediated anaerobic ammonium oxidation and vacuum evaporation, offer potential for fundamental mitigation, although techno-economic feasibility remains critical for practical implementation. Notably, the phenomenon of microaeration-driven nitrogen removal, repeatedly reported in recent studies, suggests that AD systems may possess an underappreciated micro-oxygen interface along with potentially unrecognized nitrogen transformation pathways. This observation indicates a potential paradigm shift from strictly anaerobic operation to controllable micro-oxygen regulation, representing a promising frontier for future research. This review aims to provide systematic insights into clarifying the cascading failure mechanisms of ammonia inhibition and developing next-generation, efficient, and economical mitigation strategies.

Efficient degradation of thiocyanate (SCN-) under alkaline conditions is essential to suppress the volatilization of toxic hydrogen cyanide (HCN). However, conventional catalyst-activated persulfate (PDS) advanced oxidation processes often exhibit limited efficiency in such alkaline media. This study presents a catalyst-free, thermally activated PDS system that effectively overcomes this limitation. At pH 12 and 60 °C, the system achieved complete SCN- removal within 720 min, with a reaction rate constant (5.66 × 10-3 min-1) 2.2 times higher than that at pH 2. Critically, the accumulation of the toxic intermediate cyanide (CN-) was effectively controlled, with its final concentration maintained below 0.01 mg L-1. Mechanistic studies confirmed the established pH-dependent radical transition: sulfate radicals (SO4•-) dominated under acidic conditions, while hydroxyl radicals (•OH) prevailed under alkaline conditions, accounting for 90.97% of the contribution. The superior performance under alkaline conditions is attributed to the higher reaction rate constant between •OH and SCN-, coupled with the system's inherent buffering capacity. The degradation pathway involved the sequential conversion of SCN- to CN-, cyanate (CNO-), and ultimately to NH4+, NO2-, and NO3-, with a balanced total nitrogen. When applied to real gold mining wastewater containing both SCN- and refractory iron-cyanide complexes, a hybrid "UV pretreatment + Heat/PDS" process achieved simultaneous removal of SCN- and total cyanide (to below 0.01 mg L-1), reducing the electrical energy per order (EE/O) by 74.6% compared to UV/PDS alone. This work validates an efficient and safe strategy for SCN- remediation by leveraging a homogeneous, thermally activated PDS system under essential alkaline conditions, offering a practical solution for the treatment of complex cyanide-containing wastewater.

This study investigates the efficacy and mechanisms of hydrogen/oxygen nano-bubble water (H-2/O-2-NBW) in enhancing anaerobic digestion (AD) performance. Batch experiments demonstrated that H-2-NBW and O-2-NBW significantly increased methane yields by 4.21 % to 16.98 % and 3.37 % to 13.43 %, respectively, compared to the control group (p < 0.05). Partial least squares path modeling and random forest algorithms identified 100 %H-2-NBW and 80 %O-2-NBW as optimal dosages. Under these optimal dosage conditions, semi-continuous tests revealed that methane production rates increased by 4.9-fold for H-2-NBW and 4.1-fold for O-2-NBW at an organic loading rate of 4 g volatile solids (VS)/(Ld) compared to the control group, while maintaining a stable output of 157.01-163.66 mL/gVSd at 5 g VS/(Ld) when the control failed. Mechanistic investigations indicated that O-2-NBW generates hydroxyl radicals that reduce cellulose crystallinity by 39.81 % and upregulate hydrolytic enzymes such as xylanase, cellulase, protease, and alpha-glucosidase, targeting the regulation of hydrolytic and acidogenic bacteria (Sedimentibacter). In contrast, H-2-NBW activates hydrogenotrophic methanogenesis through the stimulation of dehydrogenase, acetokinase, and coenzyme F-420, along with the enrichment of DMER64 and Methanobacterium. Microbial co-occurrence network analysis indicated that the addition of NBW significantly altered microbial interaction patterns. Functional predictions confirmed that H-2/O-2-NBW specifically strengthened the putative metabolic pathways of hydrogenotrophic methanogenesis and hydrolysis-acidogenesis. The synergistic mechanism of physical deconstruction and biological regulation of nanobubble water revealed in this study has opened a new pathway for the development of technologies aimed at enhancing AD performance.

To investigate the potential and mechanisms of bioaugmentation in overcoming ammonia and salt exposure, this study first examined the performance of food waste anaerobic digestion under two sequential batch experiments (R1, R2) exposed to salt (5-15 g/L) and ammonia (3-9 g/L), respectively. R1 and R2 proceed consecutively and under identical operating conditions. Subsequently, domesticated sludge from the highest exposure group was mixed with fresh inoculum (0 %-50 % ratio) and reintroduced into new systems with 9 g/L ammonia and 15 g/L salt exposure to evaluate performance and microbial community responses. The results demonstrated that reactor performance declined with increasing exposure levels in R1. However, under identical exposure levels, R2 consistently outperformed R1, indicating that microbial domestication enhanced reactor resistance to both ammonia and salt exposure within the tested ranges. In bioaugmentation experiments, all test groups exhibited superior digestion performance compared to controls. While salt-exposed groups showed no significant differences across domesticated sludge dosages ( p > 0.05), ammonia-exposed reactors displayed improved performance with the increasing domesticated sludge ratios. Microbial analysis revealed that sequential exposure enriched 7 salt-tolerant and 8 ammonia-tolerant genera. However, only a subset of these resilient genera (4/7 in salt-exposed and 3/8 in ammonia-exposed groups) successfully colonized the bioaugmented systems. Notably, the introduction of domesticated sludge triggered a "microbiological domino effect ", enriching functionally redundant non-dominant microbes, which likely contributed to the enhancement of digestion performance.

Passivation of metal catalysts hinders heterogeneous catalytic ozonation in degrading refractory organic pollutants (ROP). With strong electron interactions, polymetallic catalysts can enhance interfacial electromigration and regenerate active sites, improving ROP degradation. In this study, a Ni-Cu@Fe-Ceramsite catalyst was developed by co-doping nickel and copper onto Fe-ceramsite derived from sludge digestion residue, targeting ozonation of fiberboard wastewater. Morphological analysis showed nickel and copper uniformly distributed on the catalyst surface, increasing active sites while preserving porosity. Ni-Cu@Fe-Ceramsite achieved a 76.1 % removal of ROP at an initial CODcr concentration of 260 mg/L, representing a 14.6 % increase in ROP degradation efficiency and a 12 % improvement in ozone utilization compared to unmodified Fe-ceramsite. Additionally, it outperformed ozone alone by 33.6 % in degradation efficiency and 23 % in ozone utilization. The enhanced performance is attributed to the synergistic effects of nickel, copper, and iron, which boost metal reduction and the catalyst's electron-supplying ability, initiating reactions that decompose ozone molecules into reactive oxygen species such as center dot OH, center dot O2-, 1O2. This study underscores the potential of Ni-Cu@Fe-Ceramsite as an effective catalyst for wastewater treatment.

To address the problem of wellbore instability in the development of deep coalbed methane reservoirs in Daniudi gas field, this study takes the coal seam cores from Member 1 of the Taiyuan Formation at a depth of approximately 2880 m as the research object. Through CT scanning, scanning electron microscopy (SEM), mineralogical analysis, laboratory mechanical tests, and drilling fluid interaction experiments, the study investigated the coal seam fabric characteristics, mechanical response, anisotropy, and the interaction between drilling fluids and the formation. Based on the double-weak-plane criterion, a wellbore collapse prediction model was established, and instability risk assessment under multi-factor coupling conditions was carried out. Experimental and computational results indicate that the deep coal seam exhibits significant heterogeneity in fabric structure, the clay minerals show low swelling potential, and the bright coal and semi-bright coal are prone to instability due to their dual pore structures. The average uniaxial compressive strength (UCS) of the coal cores is 16.3 MPa, which is weaker than that of the roof, floor, and dirt band. The coal also exhibits anisotropy, with the lowest strength occurring when the loading direction forms an angle of 30–60° with the weak planes, corresponding to 67.5% of the intrinsic compressive strength. Immersion in drilling fluid causes the coal rock strength to decay in a pattern of “rapid decline in the initial stage—gradual decrease in the middle stage—stabilization in the later stage.” After 24 h, the strength is only 55–65% of that in the dry state. Due to its excellent plugging and inhibition performance, HX-Coalmud drilling fluid delays strength loss more effectively than the strongly inhibitive composite salt drilling fluid. The wellbore instability risk assessment indicates that as the drilling time is extended, the collapse pressure rises significantly. After 7 and 20 days of contact between the wellbore and drilling fluid, the equivalent collapse pressure density increases by 0.08–0.15 g/cm3 and 0.13–0.20 g/cm3, respectively. Therefore, homogeneous isotropic models tend to underestimate the risk of wellbore collapse. The findings can provide theoretical and technical support for the safe drilling of deep coalbed methane in Daniudi gas field.

We present an improved Anaerobic Digestion Model No.1 (ADM1) that models methane production under different organic load conditions during the anaerobic digestion of food waste. Modifications to the model include structural modifications and the addition of inhibition functions, including a proposed volatile fatty acid suppression function that takes into account both microbial concentration and inhibitor concentration. Model modification and simulation were carried out using AQUASIM 2.0 software. Two batch experiments and one semi-continuous experiment were used to calibrate and validate the modified model, called ADM-FWAI. The predictions of the new model agreed well with experimental data for methane production under stable operating conditions and during acidification inhibition (R-2>90 %). The new model provides additional information about fluctuating process parameters during the acidification inhibition stage and can predict the operating state of the reactor and propose safe operating thresholds.

To evaluate the effect of vanillin, a quorum sensing inhibitor (QSI), on the defoaming potential in food waste anaerobic digestion (AD) systems, various concentrations of vanillin were introduced into different AD reactors. The performance of these systems, along with foaming characteristics, extracellular polymeric substances (EPS) parameters, and microbial community structure and functional genes were monitored. The results show that the addition of vanillin at varying concentrations effectively reduced the foaming potential of the AD system. Specifically, vanillin at low concentrations (50 and 100 mg/L) did not inhibit methane production, whereas higher concentrations (200 and 500 mg/L) significantly inhibited methane production performance (p < 0.05). Optimal methane production and defoaming performance were observed at a vanillin concentration of 100 mg/L, where its methane production rate was not significantly different from that of the control group, but foam stability was significantly reduced by 84.69 % (p < 0.05). The incorporation of vanillin suppressed AHLs-mediated quorum sensing effects, reduced the synthesis and secretion of proteins (PN), decreased the content of PN and hydrophobic PN in EPS, lowered the viscosity of the digestate, reduced the contact angle, and ultimately diminished both foaming potential and stability, thereby achieving effective defoaming.

This study investigated the effect of the partially substituting chemical fertilizers (CF) with digestate-based organic amendment (OA) on the amelioration of red soil and the growth of plant. OA with nitrogen substitution rates ranging from 10 % to 40 % were mixed with CF and applied to red soil in a pot experiment. The results indicated that plant growth was significantly enhanced in the treatment where 20 % of the CF was substituted with the OA (OA20) compared to other treatments (p < 0.05). Specifically, the OA20 treatment increased nutrient use efficiency by 54.76 %-100.42 % compared to the treatment using only CF. Furthermore, all OA treatments improved the quality of red soil, with the nutrient content significantly higher in the OA20 group than in the other treatments (p < 0.05). The parameters of total phosphorus (TP), available nitrogen (AN), available phosphorus (AP), and total potassium (TK) significantly affected the soil quality index and plant growth, serving as reliable indicators of soil quality and plant yield. Microbial analysis revealed that the bacterial Chao index and the abundance of microorganisms involved in C-N nutrient cycling, such as Chryseolinea and norank_f__norank_o__Actinomarinales, were highest in the OA20 group. Significant correlations were observed between soil nutrient content (AN, AP, and TK) and the abundance of norank_f__norank_o__Actinomarinales and Chryseolinea, indicating their close relationship with pakchoi growth. Consequently, digestate-based OA may positively affect plant growth in acidic ecosystems by enhancing soil properties, inducing shifts in microbial community composition, and promoting the enrichment of potentially beneficial bacteria. This study provides valuable insights for the enhancement of low-quality soils and the resource utilization of digestate.

Dissolved organic matter (DOM) is a crucial component of aquatic environments and is shaped by both natural and anthropogenic factors. In this study, we screened optical indicators associated with human-derived pollution by combining the fluorescence spectroscopy with source identification analysis. Three distinct components were identified: one microbial-like component (C1) and two terrestrial-like components (C2 and C3). Overall, the water quality was good, with autochthonous DOM dominating the composition, accounting for 66 %-69 % of the total DOM. In cluster and redundancy analyses, C2 showed a strong correlation with dichloromethane and petroleum substances, suggesting a strong correlation to gas extraction industry. While C3 was closely associated with linear alkylbenzene sulfonate, a commonly used anionic surfactant, as well as nutrients, indicating a connection to domestic wastewater discharges. This study provides a screening strategy for optical indicators which allows tracing the source of human-derived pollution in a rapid and economic way.

To investigate the potential of high-temperature pretreatment composting of food waste for the amendment of cadmium(Cd)and lead(Pb)-contaminated soil,food waste subjected to high-temperature pretreatment composting(HC),traditional composting(TC),and only high-temperature pretreatment were combined with inorganic passivators(lime/zeolite)for an indoor passivation cultivation experiment.The results indicated that HC combined with the inorganic passivators group(HLZ)exhibited the most effective passivation potential for Cd and Pb in soil,achieving passivation rates of 76.92%and 86.29%,respectively.Additionally,the residual fraction of Cd and Pb in the soil increased by 10.65%and 19.94%compared to that of the control group(CK).Fourier transform infrared spectroscopy analysis revealed that high-temperature pretreatment could facilitate the degradation of organic matter during aerobic composting,thereby improving the humification degree of organic fertilizer.As a result,the produced carboxylic acids and hydroxyl compounds were able to complex with more Cd and Pb ions,reducing their bioavailability and mobility.Moreover,the pH and electrical conductivity(EC)of the soil in the HLZ group significantly increased by 28.23%and 23.80%,respectively(P<0.05).Furthermore,the HLZ group exhibited the highest levels of available nitrogen,phosphorus,and potassium nutrients(1.62,2.94,and 1.34 times higher than in CK),as well as activities of urease,hydrogen peroxide enzyme,sucrase enzyme,and phosphatase enzyme(7.17,2.09,1.83,and 8.36 times higher than in CK).Notably,phosphatase activity was positively correlated with the passivation rates of Cd and Pb(P<0.05).The HLZ group,characterized by high phosphatase activity(23.83 mg·g-1·d-1),exhibited greater potential in passivating heavy metals Cd and Pb and improving soil ecological functions.Redundancy analysis of soil physicochemical indicators and the passivation effect of heavy metals indicated that soil pH,available nitrogen,organic matter,and EC significantly influenced the transformation of Cd and Pb fractions(P<0.01).The soil in the HLZ group possessed high pH,effective nitrogen,organic matter,and EC and particularly significantly higher levels of effective nitrogen content and EC compared to those in other treatment groups(P<0.05),which could be the primary reason for the optimal potential of HLZ in the amendment of Cd and Pb-contaminated soils.This study provides a feasible application of high-temperature pretreatment compost products from food waste and the amendment of heavy metal-contaminated soil.

Food waste digestate (FWD) composting faces significant challenges, including prolonged processing times, high emissions of odorous gases and greenhouse gases (GHGs), and poor compost maturity. To address these issues, this study investigates the effects of high-temperature pretreatment (HTP) on FWD composting by testing various conditions (temperature: 70, 80, 90 degrees C; duration: 2, 4, 6 h; aeration rate: 0, 0.1, 0.2 m3 center dot min- 1 center dot m-3). The results demonstrate that HTP significantly enhances composting efficiency, with the optimal condition (80 degrees C, 2 h, 0.2 m3 center dot min- 1 center dot m-3, referred to as the 822 group) achieving a 33.33 % reduction in composting time, a 30.94 % increase in polymerization degree (DP), and a 4.90 % improvement in total nutrient content compared to the calvinKlein (CK). Gas emission analysis reveals that the 822 group shows significant reductions relative to CK: NH3 (16.90 %), H2S (21.82 %), Me2S (41.18 %), Me2SS (32.79 %), CO2 (20.42 %), CH4 (17.12 %), and N2O (14.54 %). Microbial analysis demonstrates that HTP altered the microbial composition, increasing the abundance of microorganisms that facilitate humification while decreasing the abundance of those positively correlated with odorous gas and greenhouse gas emissions. Network analysis indicated that HTP improved the modularity of the microbial community, promoting the clustering of key functional bacteria and strengthening intra-colony interactions. This study not only identifies optimal HTP parameters for FWD composting but also elucidates the microbial mechanisms underlying its efficacy, providing a scientifically grounded strategy to improve composting efficiency and reduce environmental impacts.

Heterogeneous catalyst-activated peroxydisulfate (PDS) process has great potential in environmental remediation, but its complex preparation process, high cost, low efficiency, and unclear mechanism hinder its practical application. To overcome these limitations, we introduced an innovative metal-free biochar catalyst (SCSS-NC) derived from waste biomass through co-pyrolysis of shrimp shell and sludge with nitrogen doping. This catalyst improved its performance, achieving 78.45 % degradation of tetracycline, outperforming sludge carbon/PDS systems (46.89 %) and shell carbon/PDS systems (22 %) under the dosage of PDS (0.5 mM) and catalysts (0.5 g/L) within 60 min. This improvement stems from its increased surface area, porosity, and electron transport capabilities. Quenching experiments, delayed contaminant addition experiments, and EPR results demonstrated that the SCSS-NC/PDS system relies on electron transfer, in which activated PDS binds to the catalyst surface, forming a highly reactive composite [SCSS-NC/PDS]* to degrade pollutants. The open-circuit potential and linear scanning voltammetry results confirm the existence of an electron transfer pathway, while the situ Raman spectroscopy results validate the presence of the composite [SCSS-NC/PDS]*. The DFT theoretical calculations provide further confirmation of the conductivity, low energy barrier, and ability to expedite electron transfer exhibited by SCSS-NC. The catalyst performance and characterization before, after, and post-recovery from the reaction pinpoint key active sites: pore adsorption, sp2 graphitic carbon, and graphitic nitrogen doping sites. The SCSS-NC/PDS system demonstrates robust anti-interference capability, suggesting its potential for practical organic wastewater treatment. This study provides novel insights into economical carbocatalyst and their mechanisms for environmental applications.

Rice consumption serves as a primary pathway for human dietary exposure to methylmercury (MeHg), a potent neurotoxin predominantly formed in paddy soils. Although soil physicochemical properties exert a strong influence on MeHg production and accumulation, soil heterogeneity has hindered the identification of consistent controlling factors. In this study, a systematic meta-analysis of 22 peer-reviewed datasets was conducted to evaluate environmental regulators of MeHg contamination in paddy soils, with a specific distinction made between sites located within and outside Hg mining areas. The results revealed significantly elevated Hg and MeHg levels in paddy soils associated with Hg mining activity. Across both site types, soil pH, organic matter (OM), and total Hg (THg) were identified as key determinants of MeHg dynamics. MeHg accumulation was highest under weakly alkaline conditions (pH 7.0-8.0), while both low (<10 g/kg) and high OM (>60 g/kg) OM levels were unfavorable for MeHg accumulation. In Hg mining area paddy fields, maximum %MeHg occurred at OM levels of 30-40 g/kg, whereas in ordinary paddy fields, the optimal range was 20-30 g/kg. In addition, rice cultivation significantly absorbs soil MeHg. In acidic paddy soils, modest pH reduction coupled with appropriate OM amendments may suppress MeHg production. These findings offer important insights for the targeted management and remediation of Hg and MeHg in paddy soil.