Microplastics (MPs) are ubiquitous in wastewater treatment plants (WWTPs), but there is still much to learn about their role in WWTPs. In this study, polypropylene (PP) and polylactic acid (PLA) were added to a sequencing batch reactor (SBR), and the single and combined effects of MPs and copper ions on the wastewater treatment process were evaluated. The study revealed that single copper ions had a significant negative effect on SBR operational performance, inhibiting the removal efficiency of chemical oxygen demand (COD) and nitrogenous compounds. The removal efficiencies of COD and NH4+-N decreased to 70.61% and 16.42%, respectively, at the end of the SBR. Single MPs had no effects on SBR performance. However, when MPs coexisted with copper ions, the MPs partially mitigated the toxicity of copper ions through adsorption. In addition, the coexistence of MPs with copper ions significantly promoted the secretion of extracellular polymers (EPS). Copper ions significantly affected the abundance of copper resistance genes (CRGs), while MPs in combination with copper ions could promote the abundance of CRGs. The combination of MPs and copper ions increased the abundance of antibiotics resistance genes (ARGs) and integrons (intl1), and PLA presented a more severe risk of transmission compared to PP. Furthermore, single copper ions significantly suppressed the abundance and diversity of microbial communities, while MPs and copper ions combined to relieve the inhibitory effect of single copper ions on microbial communities. Dechloromonas, OLB12, Saccharimonadales, and Blastocatellaceae were the dominant genera in SBR. pcoA, copA, and cusA were the primary CRGs influencing the copper resistance of Dechloromonas, while sul1, sul2, tetQ, and tetM were the main ARGs affecting Dechloromonas and Saccharimonadales. This study provides new insights into understanding the effects of heavy metal and MPs contamination on the performance of SBR.

The potential of biochar as an alternative fuel for sintering is limited by its physicochemical disparities compared to fossil fuels. To address this, this study developed two combined processes by integrating hydrothermal carbonization (HTC) and pyrolytic carbonization (PC) for multi-stage regulation. The effects of process temperatures (HTC: 180/200/220 °C; PC: 400/500/600 °C) and sequences - specifically HTC followed by PC (HTC-PC) and PC followed by HTC (PC-HTC)-were systematically evaluated. Comparative tests at 600 °C showed HTC-PC biochar performed best: fuel ratio increased by 32.9%-49.9%, ash content decreased by 56.2%-70.3%, K (44.4-58.8%) and Na (31.6-67.6%) were effectively removed, with equilibrium moisture reduced by 13.5%-21.6%. It had excellent fixed carbon (71.9%-88.2 wt%), low ash (3.4%-7.2 wt%), high HHV (27.5-31.5 MJ/kg) and controlled metal content, whose combustion performance was comparable or superior to metallurgical fossil fuels. These findings provide important insights for optimizing biochar replacement rate in low-carbon sintering while maintaining sinter quality.

Microplastics (MPs) in biological wastewater treatment provide a unique niche for the enrichment of antibiotic resistance genes (ARGs) and pathogenic bacteria, yet the comparative roles of biodegradability and aging are not well-defined. This study investigated the biofilm properties, microbial community structure, and enrichment of ARGs and pathogens on pristine and UV-aged biodegradable (polylactic acid, PLA) and non-biodegradable (polystyrene, PS; polyethylene terephthalate, PET) microplastics. Pristine and UV-aged MPs were incubated in a sequencing batch reactor for 30 days to facilitate biofilm development. Microbial community assembly was analyzed via high-throughput sequencing, while targeted ARGs and integrase genes were quantified through real-time PCR. The surface biofilm biomass was ranked as PLA > PET > PS and increased by UV-aging treatment. PLA enriched more qnrA and drfA1 genes than PS and PET, whereas PS favored tetC, aac(6')-Ib-cr and ermB genes, and UV-aging promoted selective enrichment of ARGs and integrase genes on UV-aged MPs, particularly on UV aged PLA. Stochastic processes were found to dominate community assembly, and aging was observed to increase the number of bacterial genera positively correlated with ARGs. Both polymer type and aging status are critical keys of the plastisphere's biological risks in wastewater systems. These findings offer new insights into the health risks of ARGs and pathogenic bacteria enriched on different types of MPs.

Municipal Solid Waste Incineration Fly Ash (MSWI FA) is a hazardous by-product containing toxic heavy metals and persistent organic pollutants (POPs), posing serious environmental and public health risks. This review critically examines its chemical and toxicological properties, human exposure pathways, and the evolving global regulatory landscape, with particular attention to regional disparities between developed and developing nations. Conventional treatment methods such as stabilization/solidification and thermal processing reduce toxicity but are often limited by high energy demands, costs, and inconsistent long-term performance. Emerging technologies, such as nanomaterials for heavy metal immobilization, hybrid geopolymerization systems, and AI-assisted risk modeling, offer promising alternatives but face technical and scalability challenges. The reuse of treated MSWI FA in construction materials is evaluated as a viable pathway to support circular economy goals, reduce carbon emissions, and alleviate landfill pressure. However, gaps remain in long-term field validation, standardization of performance metrics, and dose-response data for health risk assessments. Addressing these challenges through multidisciplinary research, strengthened governance, and context-specific implementation will be crucial in sustainable reuse of MSWI fly ash while safeguarding both human health and the environment.

The large-scale use of lithium iron phosphate (LFP)-based lithium-ion batteries has raised increasing challenges in environmental protection and resource recovery. This study investigated the feasibility of recovering spent LFP using lactic acid assisted by hydrogen peroxide, aiming to develop an efficient, mild, and economically viable recycling process. The leaching performance of five organic acids was compared, and the results showed that the lactic acid-hydrogen peroxide system exhibited excellent selectivity for lithium extraction. Under the optimized conditions of 0.2 mol/L lactic acid, 2.5% H2O2 (vol.%), and water-bath heating at 25 °C for 30 min, the lithium leaching efficiency reached 99.4%, while the residue could be further treated to obtain high-purity iron phosphate. Kinetic analysis suggested that the leaching process was jointly controlled by surface chemical reaction and internal diffusion. High-purity lithium carbonate was recovered from the leachate through concentration and precipitation.A preliminary EverBattery-based assessment showed that the proposed route reduced total energy consumption and greenhouse gas emissions compared with conventional sulfuric acid-based hydrometallurgy, indicating its potential as an efficient and environmentally favorable recycling strategy for spent LFP batteries.

A three-electrode electrochemical system was configured in a sequencing batch bioreactor (SBR configured with electrodes, CE-SBR) to inhibit nitrite-oxidizing bacteria (NOB) and promote partial nitritation (PN) in low-strength ammonia wastewater treatment. The results demonstrated that, compared with the control reactor, the nitrite (NO2-) concentration and accumulation rate in the CE-SBR have been significantly increased from 1.02 mg/L and 0.68 % to 26.07 mg/L and 59.36% respectively. Kinetic analysis demonstrated that the maximum specific NO2- oxidation rate of the sludge and the affinity for NO2- were remarkably reduced, reflecting a notable decline in NO2- oxidation capacity of the sludge. Microbial community analysis showed that the relative abundance of NOB significantly reduced, indicating significant inhibition of NOB activity. After the shutdown of electrochemical system, CE-SBR could remain a stable NO2- accumulation for a long time. Electrochemical tests demonstrated that the carbon felt anode could adsorb NO2- in simulated wastewater and oxidize it to nitrate (NO3-). The maximum NO2- removal rate reached about 271.10 g N/(m(3)center dot d), which was higher than the volumetric ammonia oxidation rate of CE-SBR (71.33 g N/(m(3)center dot d)). NOB could be effectively inhibited by the rapid consumption of NO2- in nitrification mixture by anode. The results will improve PN of low-strength ammonia wastewater, and support the application and development of novel biological nitrogen removal techniques.

Hydrothermal carbonization (HTC) minimises the volume and environmental hazards of sludge while generating useful products. However, the substantial volumes of toxic HTC-aqueous phase (HTC-AP) generated by this technology are often overlooked, posing a significant barrier to its advancement. This review thoroughly examines the characteristics, transformation mechanisms, treatment, and recycling technologies associated with sludge-derived HTC-AP. Additionally, it suggests utilizing machine learning to forecast the properties of HTC-AP. The characteristics of HTC-AP are closely linked to the chemical properties of the sludge and parameters of the HTC process, with higher proportions of high-nitrogen sludge and higher temperatures correlating with increased toxicity. Detoxification is essential before HTC-AP recycling. Achieving the full treatment and recycling of HTC-AP in a single process is challenging and necessitates greater integration and synergy between systems. A strong connection between the upstream sludge HTC process and downstream HTC-AP value-added strategy is vital for ensuring process sustainability. Furthermore, this review proposes a novel strategy that combines a machine learning approach with multi-process integration using systems thinking to enhance the energy yield and economic performance and optimize the HTC process. This comprehensive review provides guidance for optimizing sludge-derived HTC-AP recycling and HTC process regulations, with the goal of increasing the sustainability of HTC for sludge management.

Biodegradable plastics decompose more easily into microplastics (MPs) as alternatives to traditional plastics. However, the effects of biodegradable microplastics (BMPs) on the aerobic biological treatment process in activated sludge need further investigation. This study compared the effects of three BMPs (Polylactic acid (PLA), Polyhydroxyalkanoate (PHA) and Polybutylene succinate (PBS)) with 1, 10 and 50 mg/L on nitrogen removal, microbial community and antibiotic resistance genes (ARGs) in activated sludge. The results demonstrated that 10 and 50 mg/L PHA and 50 mg/L PLA enhanced specific nitrate and specific nitrite reduction rates, promoting total nitrogen removal. The positive effects on denitrification-related functional genes (such as napA, nirK, nirS) were also identified. Additionally, 10 mg/L PLA and PHA stimulated the production of loosely bound extracellular polymeric substances (EPS). However, 50 mg/L PLA and PHA decreased the tightly and loosely bound EPS contents. The response of nitrogen removal and EPS were attributed to the shifts of dominant bacteria abundance including Bacteroidota, Chloroflexi and Acidobacteriota. Moreover, PHA and PLA promoted the abundance of ARGs and intI1 in activated sludge, particularly at high concentrations. However, PBS did not affect the nitrogen removal, EPS and microbial communities. The results might shed light on the influence of BMPs on activated sludge.

Improving the efficiency of leaching arsenic from arsenic-containing gold ores is still a problem that needs to be solved urgently by traditional biological oxidation method. In this work, the effect of oxidant on mineral leaching and the change of arsenic ion valence during biological oxidation were investigated in detail. The results showed that when 5 g/L Peroxymonosulfate(PMS) was added on the second day of bioleaching, the concentration of arsenic ion in the solution was 0.682 g/L on the 14th day of the reaction, and the leaching rate of arsenic reached 71.06 %. Compared with the mixed microbial leaching system, the leaching rate of arsenic was increased by 8.95 %, while the content of As (III) was decreased by 12.82 %. The results of electrochemical experiments show that PMS plays a cathode strengthening role in mineral oxidation and the passivation phenomenon in the process of microbial leaching is reduced by improving the oxidation capacity of the system. And the dissolved charge transfer resistance of the mineral is reduced from 44.17 S2 to 32.29 S2. This study provides a new research perspective for improving the arsenic leaching rate of arsenic-containing gold ores, and our strategy also provides guidance for the research mechanism of increasing the arsenic leaching rate.

There is increasing interest in measuring the effect of microplastics and nanoplastics (MNPs) in the environment, but it is difficult to compare the results obtained in these studies due to variations in the extraction and characterization techniques, as well as the variability of the matrices analyzed. Here we provide a workflow consisting of three separate procedures for (1) preprocessing of different environmental samples, (2) methods for MNP extraction (four-step extraction method) and (3) techniques for qualitative and quantitative characterization of MNPs. The four-step extraction method (FSEM) involves predigestion, predensity separation, postdigestion and postdensity separation. This process has been optimized to maximize recovery (between 83.7 This Protocol describes preprocessing of different environmental samples and extraction of microplastics and nanoplastics, as well as qualitative and quantitative characterization of microplastics and nanoplastics. The analytical technologies used for characterization include attenuated total reflection-Fourier transform infrared spectroscopy, laser direct infrared spectroscopy and optical photothermal infrared microspectroscopy.

Bioleaching is frequently applied to low - grade ores, and mixed - strain leaching can be influenced by factors such as temperature and substrates. This study compared the cooperative leaching effects of mesophilic and thermophilic strains, including Leptospirillum ferrooxidans (L. f), Acidithiobacillus caldus (A. c), and Sulfobacillus thermosulfidooxidans (S. t). An efficient strain combination of (L. f + A. c): S. t =1:1 was identified. Subsequently, the original sparger was replaced with a nano - aeration pipe (NAP) to investigate its impact. Results indicated that NAP considerably elevated the oxygen uptake rate (OUR) and volumetric mass transfer coefficient (kLa) within the reaction system. Moreover, by analyzing the extracellular polymeric substances (EPS) content in leaching samples and assessing the microbial community, it was shown that the improved sparger, namely NAP, increased EPS content and altered the dominant bacterial groups in bioleaching. Leaching efficiency rose by 3.61 %, while daily energy consumption fell by 1.59 %. Scanning electron microscopy also confirmed that NAP enhanced microbial leaching. This study not only improves leaching efficiency and demonstrates economic potential but also offers a novel perspective for optimizing stirred - tank technology in bioleaching.

Dissolved organic matter (DOM) universally present in drinking water reacts with chlorine-based disinfectants to form disinfection byproducts (DBPs) such as trihalomethanes (THMs), haloacetic acids (HAAs) and other potentially more toxic compounds. Given that DOM removal is the primary goal of drinking water treatment, establishing models to predict DOM removal by coagulation is crucial for intelligent control in drinking water treatment plants (DWTPs). However, due to the lack of online methods for characterizing DOM reactivity in coagulation, predicting its performance for various water sources and variations of applicable seasonal conditions remains a great challenge. This study demonstrates that while DOC removal exhibits significant variations, it is primarily determined by the maximum DOC concentration removable by coagulation (DOCmax), the alkalinity in source waters, and coagulant type and its dosage. The main finding of this study is that DOCmax can be determined based on the properties of absorbance Band A3, identified as a deconvoluted Gaussian band within the Ultraviolet-Visible (UV-Vis) absorbance spectra of DOM, with the Band A3 maximum near 350 nm (R2 = 0.84). This result allows developing a universal model that accurately predicts, based on UV-Vis absorbance spectra of source waters, DOC removal by coagulation for a wide range of source conditions, alkalinity, and coagulant dosage (R2 = 0.93). These insights can be used to develop smart dosing systems for control of coagulation in DWTPs.

Municipal solid waste incineration fly ash (MSWI fly ash), classified as hazardous waste due to its heavy metal and dioxin content, requires urgent attention for large-scale safe disposal. High-temperature thermal treatment effectively immobilizes heavy metals and decomposes dioxins while enabling resource utilization of MSWI fly ash treated products. Although previous studies have examined heavy metal stabilization in MSWI fly ash, comprehensive evaluation of the treatment products against Chinese standards GB 41015-2021 and HJ 1134-2020 remains limited. This study optimized the high-temperature thermal treatment processes for MSWI fly ash, identifying three standard-compliant resource utilization pathways with their respective application scenarios and energy consumptions: (1) Using 45% industrial waste slag at 1250℃ yielded products meeting GB 41015-2021 at 1793.5 yuan/t FA. (2) Permissible utilizing urban centralized treatment facilities, the lowest energy consumption for washed fly ash thermal treatment is 1360.7 yuan/t FA. (3) Explicitly available washed fly ash treatment products application in cement mortar production, the minimum energy consumption drops to 787.5 yuan/t FA.

Hydrothermal treatment of septic sludge can result in the transfer of significant amounts of dissolved organic matter (DOM) into the hydrothermal liquid (HL). However, there is a lack of research exploring the relationship between temperature-sensitive fractions of DOM in HL and ecological risks. In this study, spectroscopic techniques combining two-dimensional correlation spectroscopy (2D-COS), self-organizing maps (SOM) and structural equation modeling (SEM), respectively, were employed to investigate temperature-sensitive DOM and its potential correlation with phytotoxicity at five process temperatures (180-340 °C). The findings revealed that DOM content peaked at 260 °C, measuring 7625 mg·CL-1. At peak levels, the concentrations of chemical oxygen demand, ammonium nitrogen, total nitrogen, and total phosphorus in the HL reached 16900 mg L-1, 34.8 mg L-1, 1920 mg L-1 and 756 mg L-1, respectively. Results from EEM-PARAFAC-SOM indicated that temperature significantly influences the variations in fluorescent components within DOM. Additionally, 2D-COS analysis identified conjugated structures and critical turning points at 220 °C and 300 °C. Notably, the -CO-NH- functional group, which is closely associated with aromatic protein II, exhibited the highest sensitivity to temperature changes. Wheat seed germination experiments revealed that the DOM sample at 180 °C exhibited the most pronounced inhibition of wheat root length, while demonstrating the least effect on germination. In contrast, seed growth was most severely impaired at 340 °C. SEM analysis revealed the influence of temperature-both direct and indirect-on the properties of DOM, identifying aromatic protein I as the primary determinant limiting seed germination. This research provides valuable insights for the management and utilization of HL.

The removal and recovery of ammonia from wastewater are critical processes for achieving global environmental sustainability and promoting circular economic development. High-gravity technology is an advanced solution to achieve ammonia stripping from wastewater. This study used machine-learning (ML) techniques to provide more comprehensive insights on various influencing factors, including the operating parameters, wastewater characteristics, and design parameters of rotating packed beds. Bayesian auto-optimization combined with a boosting algorithm effectively overcame the challenges of modeling complex datasets with small sample sizes, multidimensional data, missing values, and skewed distributions. Accurate ML based predictive models for the ammonia removal efficiency (eta) and mass transfer coefficient (KLa) were developed, the performance on the training set was R2 = 0.98 and R2 = 0.89, and on the testing set was R2 = 0.98 and R2 = 0.82. The developed model revealed that the stripping stage and gas-liquid ratio were the most influential features for predicting eta, whereas the liquid flow and high-gravity factor were the most important features for predicting KLa. The well-trained model was then deployed in an online software application that could provide both predictive and auto-update functions for operators and managers, ensuring that practitioners could use the model. The end-to-end machine-learning approach used in this study-that is, covering data collection, model development, and application-could improve the availability of research results, providing valuable references for the further advancement of technology in the field of environmental.

Microplastics (MPs) in water environment are potential carriers for many substances. In this study, pristine degradable poly-L-lactic acid (PLLA) and non-degradable polyethylene terephthalate (PET) MPs and their UV-aged counterparts were exposed to the Yuhangtang River (Y-River). The results showed that the surface morphology and structure of all MPs markedly changed after exposure. Oxygen-containing functional groups and hydrophilicity of aged MPs were higher compared with their pristine counterparts, and further increased after river exposure. The content of extracellular polymers (EPS) of biofilms on MPs increased with the exposure time, and was higher on aged MPs than on pristine ones. Similar results were obtained for most antibiotic resistance genes (ARGs) between pristine and aged MPs, and ARGs were positively related to pathogens. Dominant bacteria on all MPs were Proteobacteria (51.3 %-81.1 %), Chloroflexi (5.2 %-20.9 %) and Firmicutes (0.4 %-15.9 %), which markedly differed from the Y-River community. Aged MPs could enrich more microbes but relatively fewer bacterial species than pristine MPs, and higher enrichment and species diversity were observed on PLLA compared with PET. This study demonstrates that MPs are highly effective carriers for microbes, and the results provide valuable insights for evaluating the potential impact of bio-MPs on aquatic ecological environment.

Nutrient recovery and recycling are of great importance in sustainable development. Blackwater (BW) refers to wastewater from toilets, which contains feces, urine, water, and toilet paper from flush toilets. The highly concentrated nutrients of blackwater could be collected through source separation and treated adequately to recover nutrients efficiently and economically. The review intends to give an overview of the characteristics of BW and different techniques to recover nutrients and other valuable products. A number of these technologies are currently under development or being tested at laboratory or pilot scale. The perspective for blackwater nutrient recovery technologies is very positive due to their great potential. For application of source-oriented sanitation infrastructure and systems, there is still a long way to go for development of commercial technologies and valuable products.