The removal efficiency of glyphosate may be affected due to the quenching process of radicals by in-situ produced inorganic phosphorous. To address the problem, we have developed a novel approach to achieve the direct electron transfer between glyphosate and PMS by adding NaOH to adjust the pH values. The effectiveness and mechanisms of glyphosate degradation in various NaOH concentration were evaluated by several experiments: optimizing the concentrations of reactants, radical trapping tests, and electron paramagnetic resonance (EPR) characterization. Varying pH could change the morphologies of glyphosate and PMS, as a result, accompanied the various glyphosate removal rate. Under alkaline condition, the mechanisms of glyphosate degradation depended on the direct electron transfer process, and insignificant contribution of hydroxyl and sulfate radicals. Thus, it effectively prevented the negative effects on radical oxidation by produced inorganic phosphorous during glyphosate removal processes. As a result, glyphosate (10mg/L) was completely decomposed after five minutes with the addition of 5mmol/L PMS and 6mmol/L NaOH.

Based on the acidic and phosphorus-rich properties of phosphogypsum (PG), it was dope-modified (PO-PG) to cement (PO) and used for lead removal from acid mine wastewater. The results showed that PO-PG removed more than 99% of lead at different concentrations (15~100mg/L) with suitable dosage; under the reaction conditions of initial pH=3, PO-PG dosage of 0.2g/L, and 25℃, the effect of PO-PG on the removal of lead from 30mg/L Pb²⁺ was completely removed in 20min instead of 120min for PO; meanwhile, PO-PG had a high affinity for lead, and the removal effect of lead remained stable in the simulated wastewater with complex composition. Mechanistic analysis showed that isomorphous replacement and surface heterogeneous chemical precipitation were the main mechanisms for lead removal by PO-PG, Ca(OH)₂, CaCO₃ and Ca₅(PO₃)₃ OH were the main lead removal factors in PO-PG, and Pb²⁺ is removed by lattice displacement and other chemical reactions with Ca²⁺ to form a water-insoluble precipitate, and the products of the lead removal mainly included PbCO₃, Pb₃(CO₃)₂(OH)₂, Pb(OH)₂ and Pb₅(PO₄)₃ OH precipitates. In summary, the doping of acidic PG can accelerate the hydration rate of alkaline PO, thus improving the reaction efficiency and alleviating the problem of high pH in PO-treated effluent, in addition to the presence of phosphates in PG can be an effective species for lead removal. This study provides a cost-effective and efficient new method for the removal of lead from acid mine wastewater and can realize the resource utilization of phosphogypsum.

Sulfate radical (SO₄^•−)-based advanced oxidation processes (SR-AOPs) are characterized by in situ generation of SO₄^•− with strong oxidation capacity, which can effectively degrade a variety of organic pollutants. However, SO₄^•− can transform nitrite (NO₂⁻) and bromide (Br⁻) into toxic nitrated byproducts and halogenated byproducts, respectively. In this study, the mechanisms underlying the formation of nitrated and brominated byproducts on the reaction system in which NO₂⁻ and Br⁻ coexist were systematically investigated. Results showed that three nitrated byproducts, including 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol were produced during the heat-activated persulfate nitrification process. It was observed that nitrophenols accounted for approximately 34.5% of the phenol transformed under reaction conditions of [phenol]= 50µmol/L, [NO₂⁻]=100µmol/L,[PDS]=2mmol/L and temperature of 60℃ C. Once NO₂⁻ was co-present, the formation rate of nitrophenol was significantly accelerated. The conversion rate increased to 46.0% under the same conditions. Br⁻ can be oxidized by SO₄^•− to form reactive bromine species, which rapidly react with NO₂⁻ to form a strong oxidizing agent, nitryl halide. Then nitryl halide reacts with the phenol and plays a key role in promoting the formation of nitrophenol. Note that, Br⁻ is eventually released and acts as a catalyst equivalent. Meanwhile, the presence of NO₂⁻ results in an inhibition of the rate of formation of brominated byproducts, such as dibromoacetic acid. Therefore, the transformation mechanisms of NO₂⁻ and Br⁻ influence each other in SR-AOPs. When they coexist, promote the formation of nitrophenol byproducts but inhibit brominated byproducts.

In order to clarify the interference effect of multiple coexisting pollutants on the degradation of target pollutants during the irradiation treatment process of complex wastewater, a multivariate pollution model was constructed according to the composition of typical antibiotic wastewater, and radiolytic degradation experiments under different conditions were designed. The results showed that ionizing irradiation could effectively improve the water quality of cephalosporin antibiotic wastewater. After irradiation at 5kGy, the COD and TOC of the pollution model decreased by 15.4% and 13.9%, respectively. The degradation percentage of the target pollutant cefotaxime sodium (CTX) in pure aqueous solution reached more than 93%. The coexisting compounds in the pollution model all have a certain degree of interference effect on the radiolytic degradation of CTX, and there is no significant correlation between the intensity of the interference effect and the relative concentration. After irradiation at 5kGy, the degradation percentage of CTX in the pollution model was 11.8% lower than that in pure water. There were differences in the interference modes of CTX degradation when the coexisting substances existed alone (binary model) and at the same time (multivariate model). Benzothiazole, thiourea and MIBK had the greatest influence on the degradation of CTX when existing alone, of which the interference effects Δk_p were 0.18, 0.14 and 0.12, respectively; while thiourea, benzothiazole and xylene had the greatest interference effect on the degradation of CTX when existing simultaneously, the de-interference effect Δk_n were 0.22、0.17 and 0.03, respectively. The sequence of the reaction between different compounds and free radicals and the interaction between the coexisting substances have a significant effect on the degradation of CTX.

We systematically investigated the effects of two model foulants, sodium alginate (SA) and bovine serum albumin (BSA), on the efficiency of the PRO process and organic fouling behavior on both sides of the membrane when natural seawater was used as the draw solution. The presence of foulants in the feed solution led to the flux reduction caused by the fouling within the support layer, in which the fluxes of SA and BSA decreased by 42.54% and 30.99%, respectively. When filtering BSA with smaller particle size instead of SA, it led to a more significant membrane fouling due to the blockage of internal pores in the support layer. The flux was 10.08% lower in SA filtration compared to BSA in the presence of model foulants in the draw solution, with fouling behavior primarily existed on the membrane surface. According to the XDLVO theory, the interfacial energy barrier of SA towards the feed solution side was lower than that towards the support layer side, leading to less repulsion with the active layer side of the membrane and increased membrane fouling. Conversely, BSA showed lower repulsion towards the membrane support layer side, suggesting that BSA existed on the feed solution side lead to more significant membrane fouling behavior, resulting in greater flux loss.

Box-Behnken response surface methodology (BBD-RSM) and back propagation artificial neural network (BP-ANN) algorithms were used to model and predict the process parameters (contact time, initial concentration, temperature, pH) of activated carbon adsorption of total phosphorus (TP), and the reaction conditions in the BP-ANN model were optimized in combination with genetic algorithms (GA). The results showed that in the BBD-RSM model, the P<0.0001, which could better predict the TP removal process, and contact time was the most significant parameter for TP removal, with the relative influence order of the factors in the TP adsorption process being: contact time > pH > temperature > initial concentration. The BP-ANN model was used for optimization, and the optimal network structure was 4-8-1. Sensitivity analysis showed that the factors affecting the TP removal rate were ranked as contact time (34.05%) > pH (28.67%) > temperature (19.56%) > initial concentration (17.72%). Based on the BP-ANN model, the GA was used to optimize the operating conditions of the artificial percolation system, and the optimization results for the TP removal process were: contact time of 720.53min, initial concentration of 2.75mg/L, temperature of 30.62℃, and pH value of 5, achieving the optimal removal rate (99.63%). Experimental validation analysis showed that BP-ANN-GA had a higher R² (0.9939) and lower RMSE (1.2851) compared with BBD-RSM when predicting against the experimental values, indicating that this model had better predictive ability and could better describe the TP removal process in the constructed rapid infiltration (CRI) system.

Based on water quality indicators, climate indicators, and wetland operation parameters, data from previous studies were collected to predict the effluent concentrations of ammonia nitrogen (NH₄⁺-N), COD, sulfamethoxazole (SMX), and some heavy metals in constructed wetlands using three machine learning models. The results showed that the Random Forest model slightly outperformed XGBoost and LightGBM in overall performance, demonstrating more stable R² and RMSE values. In particular, it achieved higher accuracy in predicting NH₄⁺-N and SMX concentrations, with R² values of 0.93, 0.89, and 0.87, respectively, for NH₄⁺-N. In contrast, the models performed relatively weaker in COD predictions, with R² values of 0.71, 0.61, and 0.64, respectively. By incorporating the SMOTE data augmentation technique, the prediction performance and accuracy of the models were significantly enhanced, especially for COD, where improvements ranged from 7.04% to 26.23%. This study combines scientific data analysis with machine learning algorithms, providing a feasible approach for practical engineering applications.

This study investigated the regulatory mechanisms of zero-valent iron-graphite composite materials (0~4.0g/L) on sludge fermentation via chain elongation(CE) systems through a gradient dosing approach. The enhancement of iron-carbon materials on the CE process were systematically analyzed by monitoring the variations of short-chain carboxylic acids (SCCAs) and medium-chain carboxylic acids (MCCAs) concentrations, decomposition and metabolism of organics, electron transfer efficiency, and evolution of microbial community structure. The results demonstrated that the MCCAs production reached 10.65g/L at an iron-carbon dosage of 0.5g/L, representing a 2.04-fold increasement compared to the control group. The selectivity of caproic acid reached 53.60%, enhanced by 24.96% compared to the control. Mechanistic studies revealed that iron-carbon materials influenced the three stages of anaerobic fermentation (solubilization, hydrolysis, and acidification), promoting the decomposition and metabolism of organics and the conversion of polysaccharides to SCCAs. Simultaneously, a significant enhancement in electron transfer activity was observed in the groups with iron-carbon addition. Microbial community analysis further indicated that iron-carbon materials increased the relative abundance of the phylum Firmicutes and the genus Clostridium sensu stricto 12, which facilitated hydrolysis and CE processes in anaerobic fermentation. This study suggested that the application of iron-carbon materials could enhance MCCAs production in sludge anaerobic fermentation systems.

This study systematically investigated the synergistic interactions between biochar and the model electroactive microorganism Shewanella oneidensis MR-1 in electron transfer processes through comprehensive electrochemical analyses, kinetic modeling, and electron pathway characterization using chromium(VI)-contaminated soil as the experimental matrix. The biochar-based microbial agents demonstrated effective Cr(VI) bioremediation, with biological reduction mediated by MR-1identified as the predominant mechanism following dual-process kinetics. Optimal remediation performance (96.30% Cr(VI) reduction efficiency) was achieved under conditions of 25mg/kg Cr(VI) contamination, 5% (w/w) biochar-based microbial agents dosage, and 30% soil moisture content. Comparative analysis revealed distinct temporal remediation patterns: adsorption-based biochar-microbial composites exhibited rapid initial Cr(VI) sequestration but limited long-term stability, whereas encapsulation-based formulations showed gradual but sustained reduction capacity. Mechanistic studies demonstrated that biochar functioned as an effective microbial carrier, simultaneously enhancing MR-1proliferation and facilitating extracellular electron transfer from microbial cells to Cr(VI) contaminants through its conductive carbon matrix. Notably, the immobilized system maintained 60.44% reduction efficiency after three operational cycles, highlighting its potential for sustainable in situ remediation of chromium-contaminated soils.

In this study, we measured the contents of P in various forms in the topsoil (0~10cm) of 8representative pine (Pinus massoniana) forests in the main urban area of Chongqing. We used high-throughput sequencing technology to investigate the community characteristics of the phoD-harboring bacteria. The results showed that the surface soils of Pinus massoniana forests in the study area had relatively low phosphorus levels, with average total phosphorus (TP) contents of 192.787mg/kg in winter and 169.512mg/kg in summer. Among the inorganic phosphorus fractions, the content distribution followed the order: occluded phosphorus (O-P) > iron-bound phosphorus (Fe-P) > aluminum-bound phosphorus (Al-P) > calcium-bound phosphorus (Ca-P) > exchangeable phosphorus (Ex-P), showing a seasonal pattern of higher levels in winter and lower levels in summer. The dominant phyla of phoD-harboring bacteria in the soil were Proteobacteria, Actinobacteria, and Planctomycetes, collectively accounting for 96% of the average relative abundance. Correlation analysis showed a significant negative correlation (P<0.05) between the diversity of phoD-harboring bacteria and Al-P, as well as a significant positive correlation (P<0.05) with soil pH. Redundancy analysis indicated that Al-P and pH were the most important factors influencing the community structure of phoD-harboring bacteria. In conclusion, the topsoil of pine forests in the main urban area of Chongqing is generally P-deficient, and the P content is significantly influenced by season. The forms of P occurrence affect the community structure and diversity of phoD-harboring bacteria.