Micro-nano bubbles have unique physical and chemical properties and can form a synergistic coupling effect with traditional water treatment technologies, making them a green and efficient way for technological iteration and upgrading. Compared to ordinary bubbles, micro-nano bubbles have larger specific surface area and longer hydraulic retention time, which helps to expand the gas-liquid contact area and enhance the mass transfer efficiency. Their abundant surface charges can also promote the generation of reactive oxygen species, promoting the degradation of organic pollutants. The generation methods, common characterization techniques, and visualization methods of micro-nano bubbles were summarized. The research progress and application practices of micro-mano bubbles in water treatment processes were reviewed. The mechanism and influencing factors of micro-nano bubbles enhanced water treatment technology were systematically analyzed. The significant advantages of micro-nano bubbles arisen from their unique physicochemical properties were emphasized, especially in enhancing biochemical, physical-chemical, and membrane treatment processes. Furthermore, it was pointed out that there were still limitations in the continued in-depth research and expanded application of current micro-nano bubble technology. The key research directions for the innovation and upgrading of micro-nano bubbles in water treatment technology were also discussed.

Taking the circulating cooling water system of a certain power plant as the research object, an integrated prediction model based on “concentration ratio + influent water quality + effluent water quality” was constructed. Combined with a causal analysis framework, the relationship between effluent water quality and make-up water quality was systematically explored, and the key factors affecting effluent water quality were identified. Five relatively mature machine learning models were selected for distributed learning and prediction of the influent and effluent (i.e., make-up water and drainage) water quality of the circulating cooling water system, including temporal convolutional network (TCN), long short-term memory network (LSTM), convolutional neural network (CNN), extreme gradient boosting (XGBoost), and support vector machine (SVM). Simulation results showed that the TCN model performed optimally in all prediction tasks, with an average R ² of 0.86. The root mean square error (RMSE) and mean absolute error (MAE) were 3.15 and 2.47, respectively, and the inference time was less than 1 second, enabling fast and accurate prediction of effluent water quality. Causal inference analysis indicated that each water quality index of the effluent was most significantly affected by its corresponding make-up water index, followed by the concentration ratio. Further analysis by SHAP (Shapley additive explanations) revealed that the pH of influent had different directions of influence on different effluent indices, with a positive effect on ammonia nitrogen, and negative effects on total nitrogen, nitrate nitrogen, COD, and total phosphorus. When the concentration ratio reached 5, the system approached dynamic equilibrium, and the impact of the concentration ratio on effluent water quality weakened.

Excessive nitrogen in water bodies can lead to poisoning of aquatic organisms and eutrophication. The membrane-aerated biofilm reactor (MABR), as an emerging, efficient, and low-consumption wastewater nitrogen and carbon removal process, has garnered attention in treating low-concentration wastewater. To further expand the application of MABR in high-nitrogen wastewater treatment, this study focused on soybean processing wastewater. The raw water, effluent from anaerobic digestion via a spiral symmetric stream anaerobic bioreactor(SSSAB), and the mixed wastewater were treated in stages to examine the nitrogen and carbon removal performance of MABR. Results showed that efficient nitrogen and carbon removal was achieved by using mixed influent and appropriately adjusting the ratio of anaerobic effluent to raw water. When the proportion of anaerobic effluent was 70%, the average influent C/N ratio was 14.36, with the higher COD and total inorganic nitrogen(TIN) removal rates in MABR reaching 85.13% and 31.33%, respectively. When the proportion of anaerobic effluent was 30%, the average influent C/N ratio was 29.41, with the higher COD and TIN volumetric removal loads in MABR reaching 2.04 kg/(m³·d) and 21.24 g/(m³·d), respectively.

By loading MnO₂ on the surface of natural fibrous brucite (FB), an efficient MnO₂/FB nano-composite was successfully prepared and applied to the catalytic degradation of rhodamine B (RhB) in wastewater using peroxymonosulfate (PMS). The prepared MnO₂/FB composite was characterized, and the effects of MnO₂/FB loading and ratio, PMS dosage, pH, and temperature on RhB degradation were systematically investigated. Results indicated that the MnO₂/FB composite exhibited higher catalytic PMS activity compared to either MnO₂ nanoparticles or FB alone. Under reaction conditions of 25 ℃, initial RhB mass concentration of 50 mg/L, MnO₂/FB composite dosage of 1.0 g/L (with n(MnO₂)∶m(FB)=1 mmol∶1 g), and PMS mass concentration of 2.0 g/L, the MnO₂/FB+PMS system achieved RhB degradation rate exceeding 99%. After five cycles of reuse, the system maintained RhB degradation rate above 70%, demonstrating high stability. MnO₂/FB exhibited high PMS catalytic activity across a wide range of pH (2-10). Mechanism studies indicated that SO₄ ^·-, O₂ ^·-, ·OH and ¹O₂ generated by MnO₂/FB composite-catalyzed PMS all participated in RhB degradation, with ¹O₂ playing a dominant role. Synergistic effects between MnO₂ and FB promoted the generation of active species, thereby effectively achieving RhB degradation.

The biochar catalyst loaded with MnO _x -CeO _x (MnO _x -CeO _x /BC) was prepared by crosslinking-carbonization method. The structure of the catalyst was characterized, and the mechanism and degradation effects of COD, UV₂₅₄ and TOC in the biochemical effluent of landfill leachate under the electrocatalytic-ozone coupling system were investigated. The synthesized MnO _x -CeO _x /BC catalyst exhibited abundant oxygen vacancy formation during the Ce⁴⁺ to Ce³⁺ transition. The Mn-Ce bimetallic synergy further facilitated efficient electron transfer, thereby significantly improved catalytic performance. Moreover, in contrast to the pristine BC support, the catalyst displayed a well-defined rod-like morphology with an enhanced specific surface area and a highly porous structure, which collectively provided ample active sites for efficient pollutant degradation. When the ozone concentration was 8.1 mg/L, the dosage of MnO _x -CeO _x /BC was 60 g/L, the current density was 20 mA/cm², and the initial pH was 7, MnO _x -CeO _x /BC exhibited the best catalytic degradation performance, with the removal rates of COD, UV₂₅₄, and TOC in the biochemical effluent of landfill leachate reaching 86.5%, 92.9%, and 80% within 60 min, respectively. After six consecutive experiments, the removal rates of COD and UV₂₅₄ by MnO _x -CeO _x /BC remained above 70% and 80%, respectively. Additionally, the free radical quenching experiments demonstrated that ·OH was the main active substance during the degradation process of landfill leachate.

Water pollution control in rural areas is one of the key challenges to achieve the goal of sustainable development, and effective rural sewage treatment technology has become the focus of research and practice. A hybrid purification tank was developed for treating decentralized sewage in rural areas. Through long-term operation experiments, the pollutant removal performance of the process was systematically evaluated, and the characteristics of microbial community structure was analyzed. The results showed that the hybrid purification tank had good removal effects on COD, NH₄ ⁺-N and TN, with average removal rates of 78.74%, 98.53% and 73.94%, respectively. The average effluent concentrations were 52.85, 0.97, and 18.02 mg/L, respectively, meeting the Class B standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918—2002). The hybrid purification tank had strong resistance to shock loads. Microbial analysis showed that Nitrospira, norank_f__Saprospiraceae, norank_f__norank_o__norank_c__OLB14 were the dominant bacteria in the system, which promoted the degradation of COD and the removal of TN. Economic analysis showed that hybrid purification tank did not require complex pipeline construction, and had low operating costs, offering good application prospects in decentralized sewage treatment in rural areas.

Electronic grade ultra-pure water(E-UPW) is one of the basic production materials for semiconductor industry. It has extremely high water quality standards that require the removal of all soluble and insoluble substances from the water as much as possible. Total organic carbon(TOC) in water is one of the important indexes affecting the product yield. First, the differences between Chinese standard Electronic Grade Water (GB/T 11446.1—2013) and Standard Guide for Ultra-Pure Water Used in the Electronics and Semiconductor Industries (ASTM D5127—2018) formulated by American Society for Testing Materials(ASTM) in terms of the classification, index requirements, and detection methods of E-UPW were interpreted. Based on the source and characteristics of TOC, the efficacy, mechanism and bottleneck problems of existing E-UPW preparation technologies in the treatment of TOC were reviewed. The conventional technologies(pre-treatment, desalination, polishing) adopted the combined process of activated carbon adsorption, reverse osmosis(RO), vacuum ultraviolet(VUV), and polishing resin, which could reduce TOC to 1-20 µg/L, but its removal capacity for low molecular and electrically neutral organic matter was limited. Frontier technologies such as ozone/sodium bromide, supercritical water oxidation, and sulfate radical advanced oxidation showed the potential for efficient degradation of trace organic matter. Future research should focus on optimizing AOPs-conventional process coupling mode, developing low-energy consumption activation technology, establishing dynamic evaluation models, integrating intelligent regulation to realize the efficient operation of E-UPW systems and the sustainable development of the semiconductor industry.

Homogeneous Fenton-like technology, as an efficient water treatment process, has been widely applied in the remediation of complex industrial wastewater. In recent years, the continuous proposal of novel mechanisms within homogeneous Fenton-like systems has provided new opportunities for the deep degradation of pollutants,among which the complexation-mediated interactions between metal ions and pollutants are of particular significance. This paper systematically reviewed the critical roles of metal-pollutant complexes in Fenton-like systems, with a focused analysis of the efficiency-enhancing mechanisms of complexes in three representative reaction systems: Photo-Fenton systems, H₂O₂ activation systems, and peroxymonosulfate(PMS)/peroxydisulfate(PDS) activation systems. This paper revealed that complexes significantly improved pollutant degradation efficiency by modulating metal redox cycling kinetics, lowering redox potentials, and altering radical generation pathways. Furthermore, the influences of metal ion properties(oxidation states, coordination modes) and pollutant structural characteristics(functional groups, steric hindrance) on complexation behavior were clarified. Based on these mechanistic insights, an innovative “coordination-oxidation synergy” regulatory strategy was proposed. This strategy not only provided novel perspectives for designing highly selective heterogeneous catalysts but also established a theoretical foundation for optimizing process parameters in complex wastewater treatment.

With increasingly stringent fluoride emission standards, the reverse osmosis (RO) process has been widely applied for advanced treatment of fluoride-containing wastewater in the integrated circuit (IC) industry. However, RO concentrate is characterized by a high diversity of pollutants, elevated fluoride and salt concentrations, making deep fluoride removal a critical bottleneck in RO applications. This study investigated the application of a two-stage aluminum salt coagulation process for advanced fluoride removal of RO concentrate from a water purification plant serving an IC industrial park as a case study. The results showed that when the influent fluoride concentration was 15-25 mg/L and total dissolved solids (TDS) ≥5 000 mg/L, stable fluoride removal could be achieved under optimized conditions: pH=7, total polyaluminum chloride (PAC) dosage of 1 000 mg/L, with a first-stage to second-stage PAC dosage ratio of 1.5∶1, and a reaction time of 30 minutes. Under these conditions, the effluent fluoride concentration remained consistently below 1.0 mg/L, meeting the Class Ⅲ standard of the Environmental Quality Standards for Surface Water (GB 3838—2002). Cost analysis indicated that the chemical cost of the two-stage aluminum salt coagulation process was approximately 4.06 RMB/m³. These findings provide a technical and economic basis for the practical application of the two-stage aluminum salt coagulation process in deep fluoride removal from RO concentrate in the IC industry.

The treatment, disposal, and resource utilization of dredged sediments are facing challenges in current dredging projects, while achieving effective dewatering and consolidation of sediments is a necessary prerequisite for solving this problem. The technology routes based on flocculation conditioning to enhance the dewatering and consolidation effect of dredged sediments have been at the forefront of dredging engineering applications. Regarding the dewatering and volume reduction of dredged sediments, several easily-confused concepts (such as sediment, dredged sediment, sludge) and parameters (such as moisture ratio, water content) were firstly analyzed. Secondly, by combining three common dewatering methods, namely vacuum preloading, geotextile tubes, and mechanical pressure filtration, the technical status and main bottlenecks of these methods in engineering applications were systematically analyzed. Approaches to improve the dewatering efficiency of different methods by flocculation conditioning technology were summarized. Finally, the development directions of flocculation conditioning enhanced sediment dewatering technology were discussed, highlighting the necessity of designing dedicated flocculants, achieving synergistic effects of pollution reduction and carbon mitigation, and optimizing pathways for sediment resource utilization.

In order to solve the problem of removing refractory organic matter in the deep treatment of industrial wastewater, self-made biochar(BAC) applied as a co-catalyst into the traditional Fenton system, and the treatment efficiency of secondary biochemical effluent in a pharmaceutical industrial park in Sichuan was investigated. The results showed that the addition of self-made BAC significantly increased the COD removal rate from 34.0% in the traditional Fenton method to 78.5%, and COD in the effluent was reduced from 130-150 mg/L initially to less than 30 mg/L, meeting the standard of Class Ⅳ water in Environmental Quality Standard for Surface Water (GB 3838—2002). The introduction of BAC not only promoted the generation of ·OH, but also improved the agulation sedimentation performance of the system. Correlation analysis showed that the reinforcement of Fenton reaction by BAC was mainly due to its C \stackrel{}{̿}O, carbon defects and conductivity. In addition, the optimized BAC/Fe²⁺/H₂O₂ system could effectively reduce the COD in water over a wide pH range (3-7). BAC could be reused for 4 times without regeneration. Therefore, BAC was an ideal environmental friendly co-catalyst material for Fenton reaction, which had engineering application prospects in the field of deep treatment of industrial wastewater.

The traditional operation mode of the primary circuit desalting bed in M310 pressurized water reactor(PWR) nuclear power plants poses risks such as cross-contamination between units, elevated sulfate levels, and excessive generation of radioactive solid waste. To address these issues, this study proposed and implemented three major technical optimizations. First, reducing the resin loading in the outage-specific desalting bed from 1 500 L to 500 L to achieve volume reduction. Second, separating the functions of outage and normal operation purification,with the TEP system bed exclusively purifying during outages and the RCV system bed dedicated to routine operation, thereby eliminating cross-contamination and residual pollutants. Third, adopting high-strength, radiation-resistant macroporous nuclear-grade resins to enhance resistance to degradation and minimize sulfate release. Theoretical calculations and on-site application in over 30 outages across six units demonstrated that the optimized scheme significantly improved purification efficiency, reduced radioactive waste and collective dose, and contributed substantially to chemical control and radiation protection in PWR nuclear power plants.

p-cresol is a typical aromatic phenolic pollutant found in wastewater from the coal chemical, petrochemical, pharmaceutical, and pesticide industries. It is essential to understand the microbial metabolic pathways of p-cresol for the design and optimization of microbial wastewater treatment systems. Despite the microbial degradation pathways of p-cresol have been reported, the metabolic diversity within a single strain remains unknown. This study focused on the diverse metabolic pathways for p-cresol biodegradation in a p-cresol degrading bacterium Acinetobacter sp. L1. A total of nineteen p-cresol metabolic intermediates were detected and identified in the culture of strain L1, and three possible degradation pathways of p-cresol were proposed on the basis of LC-MS analysis. The methyl oxidation, the aromatic ring hydroxylation and the phosphorylation of the hydroxyl group were possible together involved in p-cresol biodegradation by strain L1. Moreover, under optimal degradation conditions at 35 ℃ and pH=7.0, strain L1 could metabolize 22.5% of 8 mg/L p-cresol in minimal medium within 14 d, and could degrade 90% of 10 mg/L p-cresol in wastewater containing cresol within 5 d.

During industrial processes such as oil and gas exploration, extraction, transportation, and refining, leaks of petroleum-based substances lead to the widespread presence of non-aqueous phase liquids (NAPLs) in groundwater, posing serious threats to aquatic ecological safety and human health and creating an urgent need for remediation. The common disposal methods include physical, chemical, and biological. This article summarized the development and application of NAPL phase treatment techniques. The advantages and disadvantages of these methods were analyzed. Among them, physical methods can achieve relatively thorough remediation. However, traditional techniques like excavation and replacement or centrifugal disposal involve massive engineering work, while multiphase extraction technology suffers from high energy consumption, limited efficiency, and high costs. Membrane separation, whereas, places high demands on the performance of the membrane materials. Chemical methods needed a lot of reagents, which could easily cause secondary pollution. Biological treatment was greatly influenced by the ambient environment. Finally, the future development trends of NAPL treatment technologies involving in groundwater were prospected.

Saline wastewater is widely generated in the fields of chemical industry, printing and dyeing, pharmaceuticals and waste leachate treatment, etc. Its high salinity not only inhibits the effectiveness of traditional biological treatment, but also easily causes soil salinization, ecological imbalance of water bodies and other environmental risks. With the deep implementation of the “dual-carbon” goal and the continuous upgrading of the demand for the development of circular economy, the technology of saline wastewater treatment has been developed continuously, but still faces challenges. This paper applied a combination of literature research and bibliometrics to systematically show the research progress and development trend of saline wastewater in recent years with the results of cluster analysis. The principles, applicability targets, advantages and disadvantages of physical, chemical and biological methods, such as thermodynamics, adsorption, membrane separation, advanced oxidation, chemical precipitation, electrochemical method, biofilter and membrane bioreactor, were summarized. The synergistic principles and application cases of the combined process of “reduction, harmlessness and resource utilization” were highlighted, and the technological progress of multi-dimensional resource synergistic recovery (salt, water, energy, valuable metals), development of low-energy-consuming materials (e.g. anti-pollution membranes,high-efficiency electrodes), and construction of an intelligent control system (dynamic process optimization based on AI) were also emphasized. The paper also summarized the applicable treatment technologies according to the characteristics of saline wastewater in different industries, with a view to providing theoretical basis and practical instruction for building a low-carbon and high-efficiency saline wastewater management system, and promoting the transformation of saline wastewater from “standard discharge” to “resource recycling”, and supporting for industrial green upgrading and ecological environment safety.

When using phosphorus containing wastewater as the electrolyte, the iron-air battery can utilize its own produced ferrous ions(Fe²⁺) to react with phosphates in the wastewater to generate blue iron ore, thereby achieving efficient phosphorus removal from the wastewater. A dual chamber iron-air battery with a proton membrane and a single chamber iron-air battery without a proton membrane flocculation reactors were constructed, and the phosphorus removal effects of both were investigated under different initial conditions using simulated wastewater as the treatment object. Single-factor experiments revealed that the optimal phosphorus removal performance for the single-chamber and dual-chamber batteries occurred at pH levels of 9.0 and 11.0, respectively. Increasing the influent conductivity enhanced the phosphorus removal efficiency of both configurations, but the single-chamber battery was unsuitable for treating low-conductivity wastewater, while the dual-chamber battery maintained good performance under both high and low conductivity conditions. As the influent phosphorus concentration increased, the treatment efficiency of the single-chamber battery declined, whereas the dual-chamber battery retained better performance. However, excessively high phosphate concentrations could lead to membrane fouling, resulting in a slight decrease in treatment efficiency. Increasing the external resistance reduced the phosphorus removal efficiency of both battery types. However, when the external resistance reached a certain level, it alleviated passivation and raised the pH, thereby improving the phosphorus removal performance of the single-chamber battery. To verify the treatment efficacy of iron-air batteries for real wastewater, a single-chamber iron-air battery was used to treat low-phosphorus and high-conductivity industrial wastewater. Within 48 hours, the phosphorus removal rate reached 90.14%.

A novel dithiocarbamate heavy metal chelating agent(PEI-DTC) was prepared using water-soluble polyethyleneimine(PEI) as the raw material and carbon disulfide (CS₂) under alkaline conditions. The presence of abundant dithiocarbamate groups in PEI-DTC was confirmed by UV spectroscopy, infrared spectroscopy, elemental analysis,and scanning electron microscopy. The effects of the preparation conditions of PEI-DTC and the chelation process on the removal of Cu²⁺ were investigated in detail through single-factor experiments using simulated wastewater containing Cu²⁺ and contaminated soil as treatment objects. Under pH≥3, PEI-DTC could remove 99.8% of Cu²⁺ from water and 99.9% of Cu²⁺ from soil. Compared with traditional commercial sodium dimethyldithiocarbamate(SDD) and sodium sulfide(Na₂S), PEI-DTC showed stronger heavy metal removal ability, wider adaptability(pH 1-9), and higher stability. The risk of secondary leaching of Cu²⁺ after treatment was low, meeting the national solid waste landfill treatment standards. Meanwhile, PEI-DTC chelated with Fe was used to activate persulfate for the degradation of oxytetracycline(OTC) in water. Under the optimal conditions, the degradation rate of OTC could reach 83.4%.

Nanofiltration membranes are widely used in water treatment, drinking water treatment, seawater desalination, lithium extraction from salt lakes, zero discharge of industrial wastewater and other fields due to their advantages of low operating pressure and strong selective separation, while membrane pollution restricts the long-term stable operation of nanofiltration membranes in actual production. Therefore, improving the anti-fouling properties of nanofiltration membranes is crucial for ensuring the application of nanofiltration membranes. Firstly, starting from the primary preparation technology of nanofiltration membranes, interfacial polymerization technology, the research status of nanofiltration membranes with excellent performance was introduced in detail through the regulation of interfacial polymerization process and the development of new interfacial polymerization technologies. Secondly, the application of nanofiltration membranes in various fields and membrane fouling issues were briefly described. Then, the research progress of anti-fouling nanofiltration membrane preparation was reviewed from the aspects of developing new monomer materials, selecting modification materials (including nanomaterials and polymer materials), and post-treatment modification technology. Finally, the problems faced by anti-fouling nanofiltration membranes in the application process were summarized, and the future development direction of anti-fouling nanofiltration membranes was pointed out.

The domestic large-scale wet oxidation device was adopted to treat spent caustic from ethylene cracking. The effluent COD was less than 1 000 mg/L, the sulfide was stably less than 1 mg/L, the average COD removal rate was 96.4%, and the average sulfide removal rate was greater than 99.99%. When using aerobic biochemical technology with salt-tolerant bacteria as the core to treat wet oxidation effluent, the COD removal rate of direct biochemical treatment could reach up to 40%, while the COD removal rate of phenol synergistic biochemical treatment could be increased to 70%. When the dilution ratio was 8 with phenol solution, COD after 36 hours biochemical reaction had decreased to below 50 mg/L. GC-MS analysis showed that wet oxidation technology could efficiently remove odorous substances represented by thiols and sulfides from spent caustic, while the remaining organic compounds could be further removed through synergistic biochemical treatment with salt tolerant bacteria as the core. Eventually, only a small amount of organic matter, represented by toluene, remained in the effluent.

With the development of industry and agriculture and the improvement of living standards, a variety of emerging contaminants continue to be released into the environment. In particular, organophosphate esters, phthalate esters, bisphenols, per- and polyfluoroalkyl substances, antibiotics, pesticides, polybrominated diphenyl ethers, and polychlorinated biphenyls, pose a serious threat to human health and the ecological environment. The adsorption method is one of the efficient technology for treating emerging contaminants wastewater. This paper reviewed the research progress of four types of adsorbents, including biomass, natural minerals, synthetic polymers, and nanomaterials, in the treatment of emerging contaminants wastewater, compared the advantages and disadvantages of these four adsorbents in treatment process, pointed out the future research directions for the application of the adsorption method to treat emerging contaminants wastewater. This review aims to provide theoretical insights and technical support for the efficient purification of emerging contaminants in aquatic environments.