Oxygen vacancy-rich magnesium oxide (OV-MgO) microrods were prepared through the combination of chemical precipitation method with high-temperature calcination. The effects of adsorbent dosage, pH values of the solution, coexisting ions and humic acid on the phosphate removal performance were explored. The adsorption kinetic and isotherm models were used to analyze the mass transfer process and the equilibrium characteristics of phosphate adsorption. X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) were adopted to reveal the phosphate adsorption mechanisms. The results indicated that OV-MgO microrod was a mesoporous material with a total pore volume of 0.18cm³/g, and had a good acid resistance. The phosphate adsorption was influenced by SO₄²⁻ and HCO₃⁻ ions, but its adsorption capacity only decreased by 5.18% and 4.67%, respectively, exhibiting an extremely high selectivity. NH₄⁺ and Ca²⁺ ions present in the solution contributed to the phosphate adsorption based on the formation of struvite crystals and calcium phosphate precipitates. The adsorption of phosphate on OV MgO nanorods followed the fractal-like pseudo-first-order kinetic model (Adj. R²=0.9979 and RMSE=3.25). The fitting result of the Vermeulen model indicated that the intraparticle diffusion was the rate-controlling step. The maximum adsorption capacity predicted by the Langmuir isotherm model was 267.1mg/g (as PO₄³⁻-P). The adsorption mechanisms of phosphate mainly included ligand exchange, surface precipitation and oxygen vacancy capture.

Achieving anaerobic ammonium oxidation (Anammox) in low ammonia nitrogen wastewater represents a significant challenge for municipal wastewater treatment plants. This study employed a mainstream Anammox continuous-flow oxygen-limited biofilm system (DO: 0.4~0.7mg/L) and investigated the nitrogen removal performance for treating simulated domestic sewage with low ammonia nitrogen content under different influent carbon-to-nitrogen (C/N) ratios (C/N: 2~5). Long-term experimental results indicated that a C/N ratio of 3.5~4.5 achieved over 85% total nitrogen (TN) removal efficiency. There was a positive correlation between activity of Anammox bacteria (SAA) and the nitrogen removal efficiency, with the highest SAA observed at a C/N ratio of 4. Additionally, the C/N ratio significantly influenced the extracellular polymeric substances (EPS) composition of the biofilm, with the highest protein-to-polysaccharide ratio (PN/PS) and most stable biofilm structure observed at C/N:4. Metagenomic analysis identified Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia sinica as the dominant species, with relative abundances of 21.5% and 4.7%, respectively. A diverse microbial community, including complete ammonia oxidizers (Comammox), and heterotrophic denitrifiers, contributed to microbial community structure in the system. Nitrogen metabolic analysis further uncovered the involvement of partial denitrification genes (HZS、hdh) and Anammox genes (HZS、hdh) in nitrogen removal processes, thus ensuring stable and efficient mainstream nitrogen removal. Research findings are expected to provide a novel option of mainstream anammox-based nitrogen removal process for wastewater treatment plants.

In advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS), efficient activation and utilization of PMS was considered to be an important goal for the removal of organic pollutants. The piezoelectric effect driven by water flow was introduced into PMS activation in this study, using the prepared MoS₂/PVDF membrane as a piezoelectric membrane to remove tetracycline (TC) from water. The degradation efficiency of TC by MoS₂/PVDF membrane was 77.9% within 60min was showed in the results, with a reaction rate constant of 0.0231min^-1, which was higher than that of MoS₂ (0.0135min^-1) and PVDF (0.0085min^-1). Sacrificial agent experiments combined with LC-MS were used to explore the intermediates of the TC degradation process and analyze the reaction mechanism. In cycling experiments, the excellent reusability and recyclability was exhibited in MoS₂/PVDF membranes. These results indicated that under the mechanical vortex force of water flow, MoS₂/PVDF membrane can trigger piezoelectric potential and generate abundant free electrons to activate PMS, thereby producing various active substances to degrade organic pollutants.

In response to the challenge of coexisting high concentrations of fluoride (F^-) and sulfate (SO₄^2-) in photovoltaic wastewater, based on the principle of nucleation crystallization pelleting process (NCP), its efficacy and mechanisms for removing F^-in such ion coexistence systems were thoroughly investigated. Our study demonstrated that under conditions (nucleation inducer dosage 4.46gMgCl₂/gF, flow rate 67.8×10^-4m³/h, static bed height 30%, and seed particle size 80~100mesh, F^- removal efficiency reached up to 90%. To further validate the stability of the process system, continuous flow defluorination experiments were conducted over 120h. In the first stage (0~40hours), F^- removal efficiency stabilized at approximately 89%, increasing to over 92% in the second stage (40~120hours), with granule purity exceeding 90%. Analysis using XRD and Roman revealed that F^- predominantly adhered to seed surfaces in the forms of magnesium fluoride (MgF₂) and sodium magnesium fluoride (NaMgF₃). Static water contact angle tests and SEM-EDS characterization indicated that granules exhibited greater hydrophobicity compared to the raw seeds and formed a loose porous structure, thereby increasing their specific surface area and enhancing F^- removal. The ZP revealed that in pH 6~8, the seed surface was positively charged, and F^- was mainly concentrated around the surface of the seeds by electrostatic attraction, and then driven by the inducer to nucleate and grow into dense granulation on the surface of the seeds, effectively separating F^- from water.

Corn straw biochar (Y-BC) was prepared by high-temperature pyrolysis method and its structure and morphology properties were characterized with a series of analytical techniques. The effects of initial pH and co-existing ions on tetracycline (TC) removal by Y-BC activated two types of persulfates: peroxydisulfate (PDS) and peroxymonosulfate (PMS) were systematically compared. The results showed that Y-BC activated PDS system could effectively remove TC under acidic and neutral conditions (pH=3~7), and TC removal efficiency was between 69.0% to 75.7% in 60min, while alkaline conditions (pH=9~11) TC removal efficiency reduced to 47.8%~48.4%. In contrast, the Y-BC-activated PMS system demonstrated a broad pH range for TC removal, and TC removal efficiency stabilized at 80.9%~86.8% at initial pH 3~11. The Cl^- and NO₃^- anions exhibited negligible effects on both activated persulfate systems. Meanwhile, HCO₃^- showed an inhibitory effect on TC removal by the Y-BC-activated PDS system while promoting the effect by the Y-BC-activated PMS system. TC removal efficiency decreased by 7.6% and increased by 5.1% with Y-BC-activated PDS and PMS, respectively. Combined the results of X-ray photoelectron spectroscopy, quenching experiments, and electron paramagnetic resonance analysis, it was deduced that the primary active sites for Y-BC activated PDS system were defect structures, and TC degradation was mainly through singlet oxygen (¹O₂) generation and electron transfer mechanisms. Conversely, functional groups served as key active sites for the Y-BC-activated PMS system, and TC degradation was primarily via hydroxyl radical (·OH) formation.

In this study, GCW was coupled with the advanced oxidation system based on Fe²⁺ activated O₂ to achieve efficient transmission and uniform distribution of chemical agents while continuously replenishment of oxygen to groundwater, so as to enhance the remediation effect of the Fe²⁺/O₂/ligand was advanced oxidation system. The variation law of groundwater flow field and enhanced transport effect of solute under the enhancement of GCW were clarified using two-dimensional simulation tank experiment combined with visualization methods such as tracer dyeing. In addition, sodium tripolyphosphate (STPP) was selected as the ligand, and the effect of advanced oxidation system on the remediation of p-nitrophenol (PNP) polluted aquifer was investigated by injection of chemicals into the well. The results show that GCW had achieved efficient transmission of chemical agents and provided sufficient O₂ for advanced oxidation reactions. Under the enhancement of GCW, PNP was degraded throughout the simulated tank, with an average degradation rate of 62% in 15h. The results provide a new insight for efficient remediation of organic contaminated groundwater.

Passive convergence-permeable reactive barrier (PC-PRB) is an eco-friendly and sustainable in-situ groundwater remediation technology. Based on mathematical models of groundwater flow and contaminant transport, this study innovatively proposed a grid self-adaptive refinement algorithm and developed a contaminant convection-diffusion numerical simulation software PRB-Trans. Utilizing PRB-Trans, the impact of the decompression convergence process on the contaminant capture performance of PC-PRB was analyzed. Under given simulation contaminant source conditions, compared with the continuous permeable reactive barrier (C-PRB), the required PRB length (L_PRB) and PRB height (H_PRB) of PC-PRB were reduced by 40.0% and 70.0%, respectively. The PC-PRB's planar and cross-sectional contaminant treatment efficiencies were increased by 102.9% and 348.3%, respectively. The results of the investigation of influencing factors show that with the increase of the drainage pipe length (L_p), the required L_PRB and H_PRB of PC-PRB decreased, but the reduction rate gradually decreased. Simultaneously, the PRB thickness (H_PRB) increased significantly, leading to an increase in the PRB filler volume. To avoid this situation, it is recommended that the L_p/L_PRB ratio is less than 2. In addition, due to the mixing and matching function of the decompression convergence wells and the uniform water distribution function of the buffer layer, PC-PRB can effectively solve the problems of low filler utilization rate and local breakthrough of C-PRB, demonstrating its application potential in the field of groundwater remediation.

Using carboxymethyl chitosan (CMCS) and carboxymethyl cellulose (CMC) as stabilizers, two sulfidated nano zero-valent iron (S-nZVI) composite materials were synthesized in one-step. The apparent morphology, functional group composition, and surface chemical properties of the materials were characterized using SEM-EDS, FTIR, and XPS. Static adsorption experiments were conducted to analyze the removal performance and mechanisms of Cr(VI) and trichloroethylene (TCE) by the two S-nZVI materials. Furthermore, the resistance of the optimal material to interference from groundwater pH and coexisting anions was evaluated. The results showed that CMCS and CMC surfaces contained various functional groups that could form covalent bonds with S-nZVI, improving the dispersion of the sulfidated nano zerovalent iron particles. The adsorption kinetics of Cr(VI) and the degradation kinetics of TCE by the two S-nZVI composite materials were described by pseudo-second-order kinetic models and pseudo-first-order kinetic models, respectively. The isothermal adsorption process of Cr(Ⅵ) removal by the two S-nZVI composite materials was capable of being simulated by the Langmuir model. Moreover, the S-nZVI composite material stabilized with CMCS (CMCS-S-nZVI) presented the highest maximum adsorption capacity for Cr(Ⅵ), whic h was recorded as 79.46mg/g. The removal efficiency of Cr(VI) and TCE by CMCS-S-nZVI was not significantly affected by pH in the range of 6~9 or by the presence of NO₃^- and SO₄^2-. During engineering applications, the possible negative effects of Cl^- should be paid special attention to. These findings provide theoretical guidance for the effective implementation of permeable reactive barrier (PRB) technology to remediate groundwater contaminated by chlorinated hydrocarbons and heavy metals.

Heterogeneous catalytic ozonation (HCO) was used to degrade organic pollutants in water via both direct oxidation and reactive oxygen species (ROS) converted from ozonation. In general, the physicochemical catalysts properties were considered as an important factor that influenced the wastewater purification efficiency. Being attributed to stable chemical properties, easily regulated surface properties and pore structures, carbon-based materials for HCO arose much attention in wastewater treatment. Herein, the research progress and application of carbon-based catalysts for HCO in wastewater treatment were systematically discussed, which helped reader make a complete view. Furthermore, the functionalization and regulation methods of commonly used carbon-based catalysts were introduced in details, and the relationship between carbon-based materials structure and ROS generation was deeply discussed. Meanwhile, organic pollutants degradation mechanisms via radical and non-radical reaction under different reaction conditions such as water quality were expounded. Finally, the prospection and development of carbon-based materials for HCO in wastewater treatment was proposed. The results showed that carbon-based materials for HCO have broad application prospects in wastewater treatment. Future research should focus on the optimization of catalysts and the in-depth exploration of practical applications.

This study established 4treatments, straw degradation microbial agent (MC), organic fertilizer (OF), MC+OF, and control check (CK), and conducted a 120 days straw returning experiment to analyze the impact of different treatments on straw decomposition rate, soil nutrients, and soil microecology. The results demonstrated that the MC+OF treatment significantly improved the straw returning rate, especially enhanced the lignin degradation of stubborn components in the straw. After 120 days, the MC+OF group showed significantly higher rates of hemicellulose, cellulose, lignin degradation, and strawweight loss compared with other treatments, with increases ranging from 2.87% to 11.78%, 3.20% to 10.59%, 6.00% to 32.97%, and 9.49% to 26.77% respectively (P<0.05). The total amount of humus reached 70.39g/kg, a 24.87% increase compared with the CK; additionally, soil organic carbon and dissolved organic carbon increased by 33.39% and 62.00%, respectively, from their initial levels, while soil total nutrients(nitrogen, phosphorus, potassium) increased relatively by 134.21mg/kg. The combination of microbial and organic fertilizers also enhanced the activity of invertase, urease, and neutral phosphatase in the soil. Moreover, microorganisms such as Aspergillus in the MC treatment became dominant genera during the straw returning process, induced a significant enrichment of indigenous microorganisms with lignocellulose degradation functions like Alcaligenes, Ensifer, and Brevundimonas. The combination of microbial and organic fertilizers decreased the total amount of pathogenic saprophytic fungi in the soil and improved soil quality. These results indicate the immense potential of MC+OF in accelerating the recycling and utilization of straw resources.