When drinking water quality and hydraulic conditions change, the solid-liquid balance between pipe scales and water in drinking water distribution systems (DWDSs) will be destroyed, causing iron release and secondary pollution of drinking water. In this paper, dynamic experimental systems were set up to analyze the process of iron release in DWDSs under coupled changes of flow rate (v), pH, sulfate (SO₄^2-), and alkalinity (Alk). Principal component regression was used to establish the model for predicting the release of iron. The results indicated that under the condition of v=0.12m/s, pH=6.5, [SO₄^2-]=250mg/L, and Alk=100mg/L CaCO₃, the total iron concentrations in steel and cast iron pipes reached the maximum of 1.423mg/L and 0.184mg/L, respectively. A large amount of flaky and scattered spherical structures were observed in steel and cast iron pipe scales, with α-FeOOH being the main component. After the experiment, the contents of α-FeOOH, γ-FeOOH, and Fe₂O₃ in both pipe scales increased, while those of Fe₃O₄ decreased. The predictive model showed that the total iron concentrations were negatively correlated with pH and Alk, and positively correlated with SO₄^2- and v. The order of the influences of the four factors was: v > pH > Alk > SO₄^2-.

To control the addition of chlorine disinfectant in drinking water disinfection technology, and to combine the coagulation and disinfection units to reduce energy consumption, a quaternary ammonium chitosan-based flocculant (CTS-g-CHPTAC) with dual functions of flocculation and sterilization was developed. This flocculant effectively removes kaolin and Escherichia coli from wastewater. Material characterization results showed that CTS-g-CHPTAC had a higher cationicity (29.51%) and better water solubility. Flocculation performance tests indicated that the turbidity and bacterial removal rates of CTS-g-CHPTAC reached up to 98.5% and 99%, respectively, when dosages were 0.2mg/L and 2mg/L. Meanwhile, the removal rate was as high as 97% when the dosage of CTS-g-CHPTAC was only 1~1.6mg/L in the mixed simulated wastewater, and the removal rate of mixed pollutants was as high as 95% within the pH range of 5~11. It is speculated that CTS-g-CHPTAC's higher cationic content and rougher surface topography enhance charge neutralization, adsorption bridging, and net sweeping effects, leading to improved flocculation.Furthermore, CTS-g-CHPTAC has bactericidal function, which can interact with the cell wall and cell membrane of E. coli through the quaternary ammonium group on CHPTAC and the amino group on chitosan and kill E. coli.

The porous two-dimensional carbon nanosheets with high graphitization and defect sites, designated M-C and M-N, were successfully synthesized via molten salt-assisted pyrolysis of glucose, with oxysalts (K₂CO₃ or KNO₃) as additives, respectively. The oxysalts significantly enhanced the specific surface area of the carbon nanosheets. Particularly, KNO₃ promoted nitrogen doping in M-N, resulting in a maximum adsorption capacity for acid orange 7 (AO7) of 480.77mg/g, surpassing that of biochar (BC) from direct pyrolysis and M-BC from molten salt-assisted pyrolysis without oxysalts. The adsorption and catalytic degradation of AO7 removal over carbon materials exhibited a synergistic effect. The catalytic activity of M-N in peroxymonosulfate (PMS) activation was 22.64times that of M-BC and 33.48times that of BC. Additionally, the impact of nitrogen doping and other structural defects on the non-radical pathway-dominated catalytic processes was preliminarily assessed using density functional theory (DFT) calculations. This study indicates that oxysalts can significantly reduce the amount of molten salt required in the preparation of carbon nanosheets, and also provides theoretical guidance for developing bifunctional biomass-based carbon materials for highly efficient organic pollutants adsorption and PMS activation.

In this study, a full-scale CANON system was constructed to treat high ammonia nitrogen iron oxide wastewater following physicochemical pretreatment. Over the course of 165days of continuous operation, the CANON system demonstrated excellent stability and shock resistance, achieving ammonia and total nitrogen removal efficiencies (TNRE) of 90% and 80%, respectively.Spearman correlation analysis and SHAP feature importance analysis were employed to elucidate the impact of water quality and environmental parameters on TNRE. Microbial community profiling unveiled substantial shifts in microbial population structures within the system, marked by the transition of the dominant anammox bacteria from Candidatus Anammoxoglobus to Candidatus Kuenenia, accounting for a relative abundance of 13.22%. Nitrosomonas was identified as the predominant ammonium-oxidizing bacteria with a relative abundance of 1.27%. Additionally, a machine learning model based on XGBoost was developed, which achieved a predictive accuracy of over 99.9% for TNRE, with a prediction precision of 98% for new data points in practical applications. This research provides valuable empirical insights into the engineering application and intelligent development of anammox processes.

Because of singlet oxygen (¹O₂)’s strong oxidation capability and environmental friendliness, understanding the mechanism of chlorine-mediated ¹O₂ generation in electrochemical processes can enhance wastewater treatment efficiency and minimize the side effects of active chlorine. Thus, electrochemical tests and treatment of Rhodamine B (RhB) simulated wastewater were used to assess the performance of Ir-Ta/Ti and Pt/Ti electrodes. The effects of different conditions (Cl^- concentration, chlorine evolution activity of electrodes, H₂O₂ addition, O₂ aeration) on electrochemical ¹O₂ generation were also explored. The results demonstrated that the ¹O₂-dominated electrochemical system can remove over 96% of RhB and shorten degradation pathways.Efficient ¹O₂ production depends on balancing hypochlorite (ClO^-) and hydroperoxyl (HO²_-) in the system, as an excess of either suppresses ¹O₂ generation. This study provides a theoretical framework for enhancing ¹O₂ generation under various conditions and the targeted preparation and modification of electrodes.

This paper chose epoxy resin modified loess as the primary filler for the biological retention tank. It tested 48 different raw material types with varying parameters to improve the ratio of epoxy resin to loess as the benchmark (greater than 2mm/min). The corresponding epoxy resin content is 5% (b5), 10% (b10), 5% (b5d1), and 10% (b10d1). The adsorption capability of the four enhanced materials for NH₄⁺ -N and phosphate was stronger than that of conventional fillers. After the biological retention tank was filled, b5d1had the best average removal of NH₄⁺ -N and COD, reaching 93.97% and 77.5%, respectively. b5also removed NO₃^- -N(76.6%), TN (62.4%), and TP (98%) more successfully than the other two. Through microbial investigation, b5was found to contain more organisms including Chloroflexi and Steroidobacter that are engaged in the flora process. The NH₄⁺ -N, NO₃^- -N, TN, TP, and COD can all be efficiently removed by an enhanced loess packed biological tank. According to studies, loess enhanced with epoxy resin has a wide range of promotional uses, may be utilized as biological tank packing, and effectively filters contaminants in runoff rainfall.

To prepare a highly efficient heterogeneous carbon-based magnetic catalyst with excellent solid-liquid separation properties and good stability for activating potassium peroxymonosulfate (PMS), this study employed Mn.Zn.FeO (MZF)magnetic nanoparticles (MNPs) as the magnetic core, and dopamine (DA) along with powdered activated carbon (PAC) was utilized to synthesize the magnetic nanocomposite MZF@PDA-PAC through a step-by-step deposition method. MZF@PDA-PAC was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a vibrating sample magnetometer (VSM). The efficiency of MZF@PDA-PAC in activating PMS for the degradation of diclofenac sodium (DS) was investigated, along with the removal mechanism of DS and the activation mechanism of PMS by MZF@PDA-PAC. The results showed that MZF@PDA-PAC possessed a "core-shell" structure, which exhibited excellent dispersibility and solid-liquid separation performance in water. Both radical pathways (, HO· and ) and non-radical pathways (electron transfer) played important roles in DS removal in the MZF@PDA-PAC+PMS system, with DS and TOC removal efficiencies of 99.50% and 66.32%, respectively. MZF@PDA-PAC was shown to have high stability and good recyclability, which has broad application prospect in the degradation of refractory organic compounds.

Hydrogen substituted graphdiyne (HsGDY) was synthesized through an in-situ cross-coupling reaction with triethynylbenzene as a precursor. The CH₃Hg⁺ adsorption performance of the novel sp-hybridized carbon material HsGDY was studied in comparison with traditional sp²-hybridized carbon material graphene (GE). This work showed that HsGDY had an excellent adsorption performance for CH₃Hg⁺, which was significantly better than GE. When the CH₃Hg⁺ concentration was 1.25µg/L and solution pH was 7, the final removal efficiency of HsGDY with 30 mg dosage for CH₃Hg⁺ could reach nearly 100%. An increase in ion strength, a decrease in pH and the presence of Hg²⁺ would to some extent inhibit the adsorption of CH₃Hg⁺ on HsGDY due to the competitive adsorption effect. HsGDY had good regeneration performance. After 5 regeneration cycles, its CH₃Hg⁺ removal efficiency was still above 80%. By characterization methods such as Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations, the adsorption mechanism of CH₃Hg⁺ onto HsGDY was thoroughly studied. The results indicated that CH₃Hg⁺ was chemically adsorbed on the HsGDY surface, mainly due to the interaction between the acetylenic functional group and CH₃Hg⁺.

In the surface environments, magnetite (Fe₃O₄) serves as an electron receptor and donor for microbial extracellular respiration, facilitating interspecies electron transfer as a means to promote the biodegradation of organic pollutants. It has gradually found application in the realm of water pollution remediation. The interplay between magnetite and the mineral-microbe interface assumes a profoundly pivotal role. However, the biodegradation mechanism of PAHs in sediments mediated by different morphologies of magnetite remains unclear. In this paper, two different morphologies of magnetite (micron Fe₃O₄ and nano Fe₃O₄) were prepared to investigate the effect of the magnetite on the biodegradation of PAHs in sediments. Under aerobic conditions, the addition of magnetite did not appreciably reduce the total content of PAHs and certain high-ring PAHs in the sediment. Nevertheless, the introduction of magnetite significantly diminished the levels of low-ring PAHs (naphthalene and phenanthrene) in the sediment. To further investigate the anaerobic biodegradation influence of magnetite on PAHs under varying redox conditions, with phenanthrene as the target pollutant, enrichment and cultivation experiments were conducted with the indigenous degrading microbial communities in the sediment. Two forms of magnetite were introduced under different redox conditions. The results revealed that the augmented treatment with magnetite or electron acceptors somewhat promoted anaerobic biodegradation. Under natural attenuation conditions, the independent addition of micron Fe₃O₄ significantly enhanced phenanthrene degradation, whereas the effect of nano Fe₃O₄ on phenanthrene degradation was more pronounced under sulfate and nitrate reducing conditions. The phenanthrene degradation rate constant under sulfate reducing condition was 1.39 times higher than that of the control treatment. Electron transfer system (ETS) activity demonstrated that the addition of Fe₃O₄ significantly enhances microbial respiration activity.Compared with the control, the ETS activity of the nano-Fe₃O₄ and the micro-Fe₃O₄ treatment increased by 441.7%~511.2% and 113.8%~141.1%, respectively. The microbial community structure indicated that the addition of Fe₃O₄ increased the abundance of aromatic compound-degrading bacteria such as Hydrogenophaga and Ignavibacterium, and relative to micron Fe₃O₄, nano Fe₃O₄ augments the abundance of PAH-degrading bacteria, Achromobacter and Ensifer. Furthermore, nano Fe₃O₄ may mediate intermicrobial electron transfer by releasing more Fe(II) and Fe(III). These findings contribute to a deeper comprehension of the pivotal role of magnetite in the biodegradation of organic pollutants, offering a potential approach for the remediation of contaminated sediments.

Microbial-based compound enzyme was in-situ prepared using food waste as the sole substrate in this study, and the effect and mechanism of ultrasonic combined with enzymatic pretreatment on methane production of food waste was investigated systematically. Results showed that the combined pretreatment could enhance the methane production of food waste, which was higher than that of single ultrasonic or enzymatic pretreatment, while increased the enzyme dosage could further improve the methane production. The maximal methane yield could reach (369.86±14.06)mL/g VS, which was 57.21% higher than that of the unpretreated food waste. The mechanism dissection revealed that the combined pretreatment promoted the decomposition of biomacromolecules in food waste, which was transferred from solid to liquid phase, thereby improving the biodegradability of fermentation substrate. Meanwhile, it was found that the combined pretreatment changed the protein secondary structure and destroyed the surface morphology of the food waste, and the degradation sequence of the main components in food waste was protein→ lipid → starch. Moreover, the combined pretreatment reshaped the microbial community during the anaerobic digestion process by altering the characteristics of food waste, and the enrichment of Methanosaeta, a kind of acetotrophic methanogen, further enhanced the methane production.