The slow growth and environmental sensitivity of anaerobic ammonium-oxidizing bacteria (AnAOB) limit the startup and stable recovery of anammox systems. This study investigated the effects of nano zero-valent iron (nZVI) and biochar-supported nZVI (nZVI-BC) on the reactivation of starved anammox sludge in upflow anaerobic sludge blanket (UASB) reactors. Short-term operation (29 days) showed that both nZVI and nZVI-BC significantly accelerated the recovery of anammox activity. Under equal additive dosage (30 mg/L), pure nZVI outperformed nZVI-BC (16% iron content), increasing nitrogen removal efficiency by 14.3% compared to the control, versus 11.2% for nZVI-BC. Mechanistically, nZVI provided higher bioavailable iron, promoted heme c synthesis, upregulated iron transport genes (feoB, exbD, ABC.FEV), and optimized nitrogen metabolism by downregulating hao and nxr. Although nZVI-BC showed slower short-term effects, it enhanced microbial diversity and ATPase activity. These findings highlight the importance of iron release kinetics and bioavailability in anammox reactivation. This study provides new insights into the differential roles of nZVI and nZVI-BC in restoring anammox function and guiding iron-loaded material design.

Grease-rich kitchen waste (KW) challenges biological treatment via lipid inhibition and high salinity, yet provides a cost-effective bioeconomy feedstock. Maximizing economic viability requires a shift from volume reduction to high-value biochemical production. This review evaluates physicochemical constraints and explores Large Language Models (LLMs) for mining functional genes to unravel microbial degradation mechanisms. Furthermore, this work categorizes KW valorization pathways, contrasting mature bioenergy recovery with emerging biochemical synthesis. To overcome techno-economic barriers like downstream processing costs, this review highlights advanced engineering strategies—such as non-sterile fermentation and In-Situ Product Recovery (ISPR). Integrating these digital and engineering approaches offers a roadmap from laboratory to industrial scale, ensuring profitable and sustainable KW valorization.

Nitrogen loss remains a challenge in chicken manure composting. Although zeolite amendment can effectively mitigate nitrogen loss, the response mechanisms of microbial communities remain unclear. This study investigated zeolite's effects on nitrogen transformation and bacterial communities, particularly abundant and rare taxa, during composting of laying hen manure. Compared to the control without zeolite, adding 7.5 % zeolite reduced ammonia emissions by 16.91 % and nitrogen losses by 17.91 %. Adding 10 % zeolite reduced them by 31.34 % and 28.36 %, respectively. Zeolite reduced heating rates by 0.09-1.45 C-degrees/d and pH by 0.13-0.73 to facilitate ammonia mitigation. Rare taxa exhibited stronger responses to zeolite than abundant taxa. Their responses included greater compositional shifts and network restructuring, characterized by decreased clustering coefficient, density, and centralization (p < 0.05) and increased modularity (p < 0.05). Increased zeolite enhanced ammonification suppression in both subcommunities to conserve nitrogen. Furthermore, nitrogen transformation was correlated (p < 0.01) with the co-occurrence patterns and nitrogen metabolic genes of rare taxa, not those of abundant taxa. These findings demonstrate the distinct mechanistic roles of abundant and rare taxa in nitrogen conversion under zeolite amendment. This study proposes a novel strategy for enhanced nitrogen conservation via targeted regulation of rare subcommunities.

Organic pollutants are a major environmental problem in water bodies. This research will focus on developing a new semiconductor photocatalyst through the hydrothermal method to maximize the degradation rate of organic pollutants. XRD, FTIR, BJH adsorption–desorption, PL, UV–Vis, TEM, and XPS were used to characterize CuNi@ZrC. The CuNi@ZrC/PMS/light system demonstrated excellent TC degradation (95.92 %, k = 0.213 min−1) by improved PMS activation under optimal parameters (0.18 g·L−1 catalyst loading, 0.48 g·L−1 PMS concentration and 7 pH within 15 min), which is significantly higher than that of pristine ZrC (66.03 %), indicating catalytic effectiveness of bimetallic Cu/Ni sites. It was established that the rate of TC degradation was significantly higher under magnetic stirring compared to ultrasonication. The contribution of SO4•−, •OH, O2•−, e−, and h+ in the degradation pathway was confirmed by scavenging experiments, and the CuNi@ZrC catalyst was found to have excellent stability and recyclability with greater than 80 % degradation capacity over four sequencing cycles. These findings confirm that CuNi@ZrC is highly capable of degrading a wide range of pollutants (MO, TC, MB, NOR) and remains active across a wide range of real-water environments, including river, lake, tap water, and waters containing inorganic ions and HA. This paper presents a plan to design an innovative photocatalyst that will be highly efficient at degrading organic pollutants in water.

The escalating burden of food waste and the widespread prevalence of saline-alkali soils present urgent global challenges that threaten both environmental sustainability and food security. Conventional composting of food waste to organic fertilizer suffers from large space demands and long processing time. Here, we propose a dual-benefit strategy that converts food waste into organic fertilizer (FWOF) via rapid enzymatic hydrolysis for effective soil amelioration and resource valorization. A 2 % FWOF application optimally reduced soil pH and increased available phosphorus, total nitrogen, and organic carbon by 56.31 %, 16.41 %, and 95.79 %, respectively, leading to a substantial enhancement in soil fertility while keeping electrical conductivity below phytotoxic thresholds. In contrast, higher doses (5-10%) caused excessive salinity and suppressed seed germination. FWOF also restructured microbial communities, enriching Firmicutes and Actinobacteria by about 40 % while accelerating soil humification, a process essential for improving soil productivity. This study provides the first integrated mechanistic evidence that food waste-derived fertilizer can simultaneously achieve sustainable waste valorization and saline-alkali soil restoration. The proposed dual-benefit strategy offers a cost-effective, scalable, and circular economy-based solution for both urban waste management and amelioration of saline-alkali soil.

The rapid accumulation of food waste worldwide poses significant challenges to conventional waste management strategies. Recent studies have increasingly focused on the valorization of food waste for circular biorefineries. Among the multiple steps involved in biological conversion, e.g. anaerobic digestion, composting, and fermentation, hydrolysis is widely recognized as a critical rate-limiting step as it determines the release of soluble organic substrates and directly influences the efficiency of downstream biorefineries processes. Enzymatic hydrolysis offers advantages in terms of selectivity and mild reaction conditions, but its implementation is constrained by a core contradiction, i.e. food waste complexity requires adaptive, multi-enzyme systems, whereas current reliance on externally supplied commercial enzymes imposes substantial economic limitations. This mismatch has emerged as a central bottleneck in food waste biorefining. Thus, this review summarizes recent advances in improving enzymatic hydrolysis of food waste, and particular attention is given to the development of in situ enzyme cocktail production approaches, in which food waste is utilized as a fermentation substrate for generating compound enzyme systems. Such strategies enable the integration of enzyme production and substrate conversion, thereby reducing costs and improving process flexibility under heterogeneous feedstock conditions. The review further elucidates how enzyme-driven hydrolysis unlocks multi-pathway valorization, including enhanced anaerobic digestion, denitrification via functional carbon sources, biofertilizer generation, and the synthesis of high-value biochemicals from carbohydrates, lipids, and proteins. Engineering translation is addressed through process retrofitting, co-digestion strategies, and scale-up considerations. Finally, future directions are outlined toward adaptive, data-driven biorefineries, integrating machine learning, reactor innovation, and life-cycle assessment. Overall, a comprehensive framework for advancing food waste valorization toward sustainable, closed-loop systems was provided in this review, which is essential to reposition food waste management from an end-of-pipe solution to a cornerstone of circular, low-carbon biorefineries. By linking in situ enzyme cocktail production, enzymatic hydrolysis, product valorization, and engineering-scale retrofitting, this review highlights enzyme cocktails as enabling interfaces between food waste and downstream high-value bioconversion.

In recent years, the risk of antibiotics in the environment has increased due to the inefficient treatment of antibiotics in conventional wastewater treatment plants (WWTPs). This has resulted in the emergence of antibiotic resistance (AMR), which is becoming a significant public health concern in modern society. Conversely, wastewater treatment plants (WWTPs) have emerged as a pivotal site for addressing the issue, given their role as reservoirs of antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARG). It has been reported that conventional WWTPs employ specialised disinfection processes to disinfect the target water body, yet the efficacy of removing ARBs and ARGs has been found to be inadequate. This paper presents a review of the efficiency of several advanced oxidation processes (AOPs) for the removal of ARBs and ARGs from wastewater. The review focuses on the combined ultraviolet (UV) and H2O2/chlorine/peroxymonosulfate (PMS)/ozone processes, Fenton/Fenton-like/photo-Fenton, ultrasonic, and multiphase photocatalysis. The objective is to provide an analysis of their bacterial inactivation mechanisms and removal effects. It must be acknowledged that the treatment of actual wastewater still presents certain limitations, and that further comprehensive studies are required to ascertain the full potential of AOPs for the removal of contaminants.

In the context of carbon neutrality, adding conductive materials (CMs) such as biochar to anaerobic digestion (AD) systems has become a key strategy for treating high-concentration organic wastewater and promoting methane production. This study utilized biochar as bio-carriers to build an anaerobic biofilm reactor. It investigated the impacts of two kinds of biochar, one with Fenton iron sludge (FC600) and the other without (BC600), on the methane production performance of a continuous-flow anaerobic digestion system. The reactor was operated for 76 days. When the organic loading rate (OLR) increased to 18 kg/(m3 d), reactor R3 with FC600 added demonstrated the highest COD removal efficiency (98.68 %) and methane production (1230 mL/d). Concurrently, the coenzyme F420 concentration reached 0.9 mmol/g SS. Additionally, the maximum current of FC600 increased to 1.78 mA, indicating enhanced microbial charge-discharge capacity. High-throughput sequencing revealed that FC600 facilitated the enrichment of hydrogenotrophic methanogens (such as Methanobacterium), syntrophic bacteria (such as Syntrophobacter), and iron-reducing bacteria (such as Desulfomicrobium). Gene function prediction analysis further indicated that functional genes related to conductivity, especially those encoding C-type cytochrome, are most abundant in R3, and these genes can promote direct interspecies electron transfer (DIET). Moreover, key enzymes involved in methanogenesis were also highly expressed in R3, collectively enhancing its methane production capacity. This study developed Fenton iron sludge-enriched granular biochar and directly applied it as bio-carriers, providing a theoretical basis and a new technical strategy for practical engineering applications.

This research aims to explore how incorporating various materials influences gentamicin residue, enzyme activity, and microbial populations during the composting of gentamicin mycelia residues (GMRs). In the study, rice chaff, corn cobs, mushroom residue, and peanut shells were added to GMRs in specific ratios for co-composting. The results showed that the addition of rice chaff, corn cobs and mushroom residue led to a rise in composting temperature, prolonged the thermophilic phase, and enhanced gentamicin degradation. The elevated temperatures also induced shifts in bacterial community composition and fostered greater diversity. Throughout composting, gentamicin suppressed the activities of cellulase, urease, phosphatase, and catalase.

This study developed a novel strategy for food waste (FW) valorization through incorporating plant ash and biochar into enzymatic hydrolysis of FW. After 12-h hydrolysis of FW with fungal mash, the solid and soluble products were separated and harvested as solid biofertilizer and carbon source for denitrification respectively. Soluble COD produced from plant ash and biochar mediated FW hydrolysis could reach approximately 170 g/L on average, which showed a specific denitrification rate of 26.23-31.33 mg N/g MLVSS/h higher than that with commercial glucose (i.e. 25.92 mg N/g MLVSS/h). The applicability of solid biofertilizers produced from plant ash- or biochar-assisted hydrolysis of FW was evidenced by the higher germination rate of 138-166 % against that without exogeneous additives (122 %). It is expected that the proposed approach can offer an effective solution for upgrading FW into value-added products, while realizing a complete resource recycle with no wastes discharged.

The anaerobic ammonium oxidation (anammox) process presents a sustainable approach for nitrogen removal in wastewater treatment; however, its efficiency reduces in low-temperature conditions due to the inhibited activity of anaerobic ammonia-oxidizing bacteria (AnAOB). This review focuses on the response of AnAOB to low temperatures and measures to enhance their activity. Adaptation strategies of AnAOB to low temperatures increased secretion of extracellular polymeric substances and heme c, tweaking its membrane structure to increase fluidity and secreting cold shock proteins to maintain physiological functions. Despite a decrease in enzyme activity, the most noticeable reduction is in NIR. Different species of AnAOB exhibit different changes in gene expression and metabolic pathways under low temperatures. Notably, Ca. Kuenenia shows enhanced energy production and amino acid metabolism, which is more conducive to adapting to low temperatures. The composition of AnAOB and the lower activation energy also seem to confirm this point. Therefore, it is speculated that Ca. Kuenenia is more adapted to low temperature. In order to improve the performance of AnAOB in low-temperature, three strategies were adopted: chemical additives, using external physical fields and optimizing reaction conditions, aiming at enhancing enzyme activity and electron transport, improving the permeability and metabolic rate of biofilm and stabilizing microbial activity. Although these strategies have potential, their economic feasibility and long-term stability are worth considering. Future research should prioritize the synergistic integration of multiple strategies, cultivate AnAOB suitable for low-temperature growth and promote anammox applications in cold.

Oxidation performance of the Fenton-like technology decreases under near-neutral and high-salt conditions, which will hinder the deep removal of emerging contaminants (ECs). In this work, the coordination environment of Fe sites in carbon-based catalysts was regulated by gradient heating, and the model contaminant bisphenol A (BPA) was effectively degraded under near-neutral (pH=5.0-9.0) and high-salt (TDS=2922-7102 mg/L) conditions. The results show that the reactive species dominated by O-1(2) (55.84 %) and high-valent iron-oxo (44.16 %) were generated in Fe-NC-700/PMS system. According to the extended X-ray absorption fine structure and Mossbauer spectroscopy, the coordination number of Fe-N in Fe-NC-700 was 3.4. The higher isomer shift values (0.384 mm s(-1)) and lower binding energy (712.87 eV) of Fe 2p orbitals in Fe-NC-700, compared with the catalysts obtained under other temperature, will facilitate the formation of O-1(2) and high-valent iron-oxo through oxygen transfer process. And these non-radical species will overcome the bottleneck of ECs removal under nearneutral and high-salt conditions, and bring an enlightenment for the advanced purification of wastewater.

This study investigated the effect of acetic acid on reducing nitrogen losses in pilot-scale chicken manure composting and provided a comprehensive analysis of the distinct roles of abundant and rare bacteria in nitrogen transformation. Acetic acid was added at concentrations of 4.05 (AAL) and 8.09 g/kg (AAH), and physicochemical parameters, ammonia emissions, and bacterial communities were monitored. AAL and AAH reduced thermophilic-phase ammonia emissions by 27.67 % and 12.81 %, respectively, contributing to 53.48 % and 43.34 % of overall nitrogen loss reductions, respectively. Acetic acid enriched rare taxa rather than abundant taxa in the thermophilic phase, which contributed to reduced ammonia emission in AAH by promoting nitrification and ammonia assimilation. Network analysis indicated that nitrogen conversion was related to rare taxa interactions (p < 0.001) rather than abundant taxa interactions, while the relationship was enhanced in AAL but not in AAH. For community assembly, rare taxa were more affected by stochasticity than abundant taxa, while AAH enhanced the stochasticity of rare taxa (p < 0.05) but did not affect that of abundant taxa. Rare taxa assembly was related to nitrogen transformation (p < 0.05), while abundant taxa assembly was not. These results indicated that rare taxa responded differently to varying doses of acetic acid. This study demonstrated that a lower dose of acetic acid was more effective in reducing ammonia emissions during the thermophilic phase of composting and highlighted the importance of rare taxa in nitrogen transformation. This study will promote the application of organic acids for nitrogen retention in manure composting.

Antibiotics are widely used in modern medicine. However, as global antibiotic consumption rises, environmental contamination with antibiotics and antibiotic resistance genes (ARGs) is becoming a serious concern. The impact of antibiotic use on human health is now under scrutiny, particularly regarding the emergence of antibiotic-resistant bacteria (ARB) in the environment. This has heightened interest in technologies for treating ARGs, highlighting the need for effective solutions. This review traces the life cycle of ARB and ARGs driven by human activity, revealing pathways from antibiotic use to human infection. We address the mechanisms enabling resistance in ARB during this process. Beyond intrinsic resistance, the primary cause of ARB resistance is the horizontal gene transfer (HGT) of ARGs. These genes exploit mobile genetic elements (MGEs) to spread via conjugation, transformation, transduction, and outer membrane vesicles (OMVs). Currently, biological wastewater treatment is the primary pollution control method due to its cost-effectiveness. However, these biological processes can promote ARG propagation, significantly amplifying the environmental threat posed by antibiotics. This review also summarizes key mechanisms in the biological treatment of antibiotics and evaluates risks associated with major ARB/ARG removal processes. Our aim is to enhance understanding of ARB risks, their pathways and mechanisms in biotreatment, and potential biomedical applications for pollution control.

At present, the future innovative sewage treatment processes should have the advantages of resource utilization and energy self-sufficiency, of which the aerobic granular sludge process has great potential in resource recovery of high value-added biological materials based on its own characters. The relationship between the mechanism of aerobic granular sludge formation and its resource recovery is closely related. Based on the aerobic granular sludge resource recovery pyramid, the status of high value-added products deserves in-depth study. Meanwhile, the extraction methods are correspondingly different and uneconomic according to the characteristics of diverse high value-added products. Thus, the exploitation of efficient and low-cost separation and purification technologies is the key to realize the resource utilization of aerobic granular sludge.

As volatile organic compounds (VOCs), gaseous ethylbenzene has adverse effects on human health and ecology. Therefore, an effective degradation process is highly desirable. The Fenton process under UV 365 nm was selected as the first option to remove gaseous ethylbenzene in a bubble column reactor. The main parameters for the batch experiments were systematically studied, including H2O2 concentration, [H2O2]/[Fe2+], pH, UV wavelength, UV intensity, gaseous ethylbenzene concentration, gas flow rate, and process stability towards removal efficiency. The optimum conditions were found to be H2O2 concentration of 100 mmolL-1, [H2O2]/[Fe2+] of 4, pH of 3.0, UV wavelength of 365 nm, UV power of 5 W, gas flow rate of 900 mLmin(-1), and gaseous ethylbenzene concentration of 30 ppm, resulting in a removal efficiency of 76.3%. The study found that the Fenton process, when coupled with UV 365 nm, was highly effective in removing gaseous ethylbenzene. The degradation mechanism of gaseous ethylbenzene was proposed in the UV365/Fenton process based on EPR, radical quenching experiments, iron analysis, carbon balance, and GC-MS analysis. The results indicated that center dot OH played a crucial role in the process.

The treatment and resource utilization of a large amount of anaerobically treated livestock and poultry manure has become a significant research focus in sewage treatment due to the rapid expansion of large-scale live-stock and poultry farms in China.This article discussed the drawbacks and limitations of traditional biochemical treatment methods and microalgae technology in biogas slurry resource treatment,and explored the emergence and progression of bacteria-algae symbiosis technology in this area.The research status of bacteria-algae symbiosis technology were systematically examined,including the development and application of reactors,the selection of functional bacterial and algal species,the determination of bacteria-algae inoculation ratio,and the development of bacteria-algae granular sludge,all based on the mechanism and efficiency of biogas slurry treatment.Additionally,the research direction of bacteria-algae symbiosis technology in the field of biogas slurry treatment and resource uti-lization was analyzed,emphasizing the potential of bacteria-algae granular sludge resource utilization technology as a pivotal research area in biogas slurry resource treatment technology.