Pathogenic microorganisms pose a severe risk to the aquatic environment and human health. Membrane bioreactors (MBRs) have attracted much attention due to their simultaneous biological treatment and virus retention, but membrane fouling is the main obstacle. This study explored the effect of micro-granular activated carbon (mu GAC) on bacteriophage MS2 removal efficiency and membrane fouling in a flat-plate MBR. The results showed that the mu GAC addition with a particle size of 180-300 mu m improved the removal of MS2 (LRVMBR of 4.77 log) and enhanced the removal of COD and ammonia nitrogen. The mu GAC integrated MBR (mu GAC-MBR) exhibited a higher MS2 retention rate by the membrane filter layers with an average LVRMem of 2.03 log compared to that of a control reactor (C-MBR) of 1.89 log. Meanwhile, the total membrane filter layer resistance of mu GAC-MBR was significantly lower than that of C-MBR, particularly in terms of cake layer resistance and organic pore-blocking exclusion. The mu GAC addition slightly reduced MS2 adsorption by the activated sludge while significantly altering the extracellular polymeric substances (EPS) profiles. The fluorescent components in the bound EPS and PN/PS ratio of the activated sludge were reduced. We found that mu GAC enhanced membrane surface roughness and hydrophilicity. Notably, the mu GAC significantly influenced the quorum sensing (QS) systems, reducing the abundance and synthesis of AHL-related genes. The synthase luxI in the AHL-QS system was reduced by 93.21% in mu GAC-MBR. The AHL-QS system is closely related to biofilm formation, and the total EPS of the surface filer layer of mu GAC-MBR decreased by 57.73%, and PN in LB-EPS and TB-EPS decreased by 91.33% and 54.44% compared with C-MBR, indicating a significant reduction in biofilm formation. This study exhibited a new perspective on promoting MS2 removal with the synergistic effect of alleviating fouling in the MBR process.

In this work, a novel integrated Fe3O4/g-C3N4 (FC) composite and rotating magnetic field (RMF) system was developed to enhance the photodegradation of ofloxacin (OFX) in water. The RMF was excited by three-phase alternating current, providing great flexibility on the magnetic field and avoiding mechanical transmission. By integrating RMF, the OFX degradation by FC photocatalysis was greatly enhanced. With the optimal FC composition of 20 % (wt) Fe3O4 (FC20), >87 % OFX degradation could be achieved with 1 g/L FC20, an RMF-excited current of 2 A, and a reaction time of 300 min, compared to OFX decomposition of similar to 65 % by FC20 photocatalysis alone. The magnetic induction intensity, solution pH, and water matrices all affected OFX degradation by the integrated FC-RMF system. The FC20 was reliable for OFX degradation in water with minimal efficacy reduction after four consecutive reuses. In the integrated FC-RMF system, reactive species' contribution to OFX degradation was in the order of holes > superoxide anions > hydroxyl radicals. The electron transfer mechanisms during OFX degradation and five potential degradation pathways were proposed. In summary, the integrated FC-RMF system demonstrated a potential route for enhancing the removal of OFX and possibly other antibiotic contaminants from water.

CuS/Bi2O3 composite photocatalyst was prepared by calcination and in situ precipitation, and peroxymonosulfate (PMS) was applied to the degradation of tetracycline (TC) wastewater under visible light. The microscopic morphology, chemical composition, and optical properties of the composites were investigated by characterization means of XRD, FTIR, SEM, XPS, and UV-Vis DRS. The results showed that the introduction of CuS increased the specific surface area of Bi2O3 and increased the visible absorption boundary of Bi2O3 from 455 to 524 nm, which effectively inhibited the complexation of photogenerated electron-hole pairs. The experimental results showed that the introduction of PMS strengthened the removal of TC from the composites, and 95

In this study, the distribution and toxicity of nanoscale zero valent iron (nZVI) and nZVIs coated with citric acid and sodium tripolyphosphate (CA-nZVI and STPP-nZVI) in mice were investigated. nZVIs were primarily found in the livers and spleens, followed by the lungs, hearts, and kidneys. Histologic analysis revealed no significant histopathologic abnormalities or lesions in all organs except the liver at 14th d gavage. nZVIs did not have a noticeable impact on the body weight of the mice or the weight of their organs. Compared with the control group, there were no significant changes in hematology indexes in the nZVIs groups. However, the nZVIs groups exhibited varying levels of elevation in alanine aminotransferase, aspartate aminotransferase, and creatinine, suggesting liver and kidney inflammation in mice. The up -regulation of Nuclear Factor erythroid 2 -Related Factor 2 and Heme oxygenase 1 in the nZVIs groups may be a response to nZVIs-induced oxidative stress. Immunohistochemical analysis confirmed the inflammatory response induced by the three nZVI groups. Chelating agents did not have a significant impact on the distribution or toxicity of nZVIs in mice. This study contributes to a comprehensive and detailed insight into nZVI toxicity in the environmental field.

Reactive oxygen species (ROSs) in Fenton process are of great importance in treating contaminants in wastewater. It is crucial to understand their chemical properties, formation, and reaction mechanisms with contaminants. This review summarizes the reactive oxygen species in Fenton process, including hydroxyl radical (•OH), superoxide radical (O2•−), singlet oxygen (1O2), hydroperoxyl radical (HO2•), and high-valent iron. •OH shows a trend to react with chemistry groups with abundant electrons through H-atom abstraction, radical adduct formation and single electron transfer. Electron transfer is discovered to be an important pathway when 1O2 degrades organic pollutants. Ring-opening and β-scission are proposed to be the possible ways of 1O2 to certain contaminants. Proton abstraction, nucleophilic substitution, and single electron transfer were proposed to explain how O2•− degrade pollutants. As the conjugated acid of O2•−, radical adduct formation and H-atom abstraction are reported for the reaction mechanisms of hydroperoxyl radical. High-valent iron in Fenton, namely Fe(IV), reacts with certain pollutants via single- or two-electron transfer. This review is important for researchers to understand the ROSs produced in Fenton and how they react with pollutants.

Composite MgIn2S4/Bi2O3 was prepared and applied to the photocatalytic degradation of tetracycline (TC) under visible light. Results showed that formation of type-II heterojunction extended the visible light response range of the composite to 628 nm, effectively limiting the rapid recombination of photogenerated carriers. Further, the degradation experiment showed that TC was effectively decomposed by the composite. The main active substances for degrading TC were SO4·−, ·OH, h+ and 1O2. Cycling experiments showed that the TC removal rate by MgIn2S4/Bi2O3 photocatalytic material was still as high as 75% after 4 cycles without any obvious changes in the crystalline phase structure.

Among the treatment strategies for degrading antibiotic organic wastewater, advanced oxidation processes (AOPs) premised on persulfate activation have drawn extensive attention due to their high degradation capacity. Photocatalytic persulfate (PS) activation technologies are ideal and environmentally friendly. The coupling of photocatalysis and persulfate systems could indeed increase the efficiency of visible light utilization and generate more reactive oxygen radicals. As visible light responsive photocatalysts, bismuth-based photocatalysts have captivated significant interest due to the properties of low cost, non-toxicity, and excellent optical and chemical nature. At present, there are few reviews on bismuth-based photocatalytic activated persulfate. This article summarizes the research advances of the activated persulfate technique for treating antibiotic effluent with bismuth-based photocatalysts. Firstly, the mechanisms of photocatalysis and photocatalytic activation of persulfate are introduced and compared, as well as the advantages of the system and bismuth-based materials. Then, the catalytic performance and potential degradation efficiency of various bismuth-based photocatalysts are summarized and evaluated. Besides, strategies to improve the efficiency of photocatalytic activation of persulfate systems are discussed. After that, the directions that should be paid attention to or technologies explored in this kind of research are proposed. Finally, the challenges in the practical application of photocatalytic activation of persulfate are presented. The synthesis of efficient, safe, and economical bismuth-based photocatalysts and the improvement of the activated persulfate process will effectively expand its application prospects.

Sodium dodecylbenzene sulfonate (SDBS), an anionic surfactant, has both hydrophilic and lipophilic properties and is widely used in daily production and life. The SDBS-containing organic wastewater is considered difficult to be degraded, which is harmful to the water environment and human health. In this study, ferrate-assisted coagulation was applied to treat SDBS wastewater. Firstly, a single-factor experiment was conducted to investigate the effect of the Na2FeO4 dosage, polyaluminum chloride (PAC) dosage, pH and temperature on the treatment efficiency of SDBS wastewater; then, a response surface optimization experiment was further applied to obtain the optimized conditions for the SDBS treatment. According to the experimental results, the optimal treatment conditions were shown as follows: the Na2FeO4 dosage was 57 mg/L, the PAC dosage was 5 g/L and pH was 8, under which the chemical oxygen demand (COD) removal rate was 90%. Adsorption bridging and entrapment in the floc structure were the main mechanisms of pollution removal. The ferrate-assisted coagulation treatment of strengthened SDBS wastewater was verified by a response surface experiment to provide fundamental understandings for the treatment of the surfactant.

The dewaterability of waste activated sludge (WAS) plays the key role in sludge dewatering in wastewater treatment plants. The magnetic field as a source of clean energy has been reported to be able to cause changes in sludge properties and to enhance sludge dewatering by chemical treatment. This paper focuses on the effect of pre-magnetization on the sludge dewatering performance by ozonation. The results showed that ozonation reduced the capillary suction time (CST) and water content of sludge cake (Wsc) of WAS. The CST reduced from 21.5 s to 12.7 s; and the Wsc reduced from 85.6% to 85%. However, the addition of pre-magnetization with a magnetic field did not make much improvement of the dewaterability. Further investigation on sludge properties such as EPS, TOC, particle size, and the SEM images of the treated WAS showed that the pre-magnetization prior to ozonation led to stronger oxidation and WAS particle broken, which was proofed not necessarily correlated to sludge dewaterability enhancement.

The antibiotic levofloxacin was degraded by three steps of calcination, hydrothermal reaction and in situ precipitation using g-C3N4 as the substrate, and ZnO and Ag3PO4 were effectively combined to form a ternary photocatalyst of Ag3PO4/C3N4/ZnO. The morphology, structure and optical properties of the photocatalytic materials were investigated using XRD, FTIR, SEM, XPS and UV–Vis, and it was found that the three monomer materials, Ag3PO4, g-C3N4 and ZnO, formed Z-type heterojunctions, which increased the active sites of the photocatalytic materials and broadened the visible absorption spectra of the synthesized composites. The best degradation effect of Ag3PO4/C3N4/ZnO on 10-mg/L levofloxacin was achieved with the addition of 10

Microplastics that are widely distributed in the environment has raised great concerns due to their potential negative effects to humans. Zebrafish was used as the model organism in this study to assess the toxicity of microplastic exposure. The adult zebrafish were exposed to the PE microplastics in smooth clustered sphere shapes with diameters of 75-100 µm for 35 days, and the survival rate of the zebrafish were not significantly affected, whereas the growth rate was. Further analyses on the oxidative stress related enzyme activities showed that the production of GSH, GSH-PX, and GST in the intestine were stimulated when exposing to the microplastics of lower concentrations (0.1 and 1 mg/L), while the production of SOD, CAT, GSH, GSH-PX were suppressed when exposing to those of 10 mg/L. The activities of enzymes in the muscle were much less affected. The intestinal injury and changes of colony structure in the intestine were observed by exposure to the tested concentrations of microplastics. By exposure to the microplasctics for 35 days, a further concurrent exposure to microplasctics and Aeromonas hydrophila did not exacerbate the mortality of zebrafish due to bacterial infection; on the contrary, the mortality was reduced. This study confirmed the intestinal enzyme activity changes of zebrafish, but showed no sign of inducing higher mortality or exacerbating bacterial infection by chronic exposure to the microplastics.

Abstract This experiment studied the degradation characteristics of aniline and antimony in printing and dyeing wastewater by the micro-oxygen hydrolysis acidification process and its influence on the removal of COD and ammonia nitrogen. Firstly, the study optimized the control factors of pH、dissolved oxygen (DO)、sludge concentration on the removal efficiency of COD and ammonia nitrogen in hydrolysis and acidification section. It is recommended that pH can be maintained at 6.5; low dissolved oxygen (0-0.5 mg/L) would help the conversion of nitrogen substances for subsequent treatment, the optimal treatment temperature was found to be 25℃, furthermore, it is recommended to control the sludge concentration at 4 mg/L during operation. Secondly, the impact of aniline and antimony on COD and nitrogen removal was explored. It was found that when the aniline concentration increased from 0.4 mg/L to 5.4 mg/L, the effluent COD concentration increased, with a rate of 96.5%, indicating that aniline was toxic to anaerobic sludge and significantly inhibited the COD degradation; while when the antimony concentration increased from 0.05 mg/L to 2.05 mg/L, the COD removal rate was only 2.9%, which was far lower than the COD removal rate of water samples without adding antimony. The decrease of anaerobic sludge concentration from 5.58 g/L to 3.44 g/L indicated that aniline and antimony have a strong inhibitory effect on the activity of anaerobic bacteria, and reversely affect the COD removal.

The difficulties in dewatering waste-activated sludge (WAS) using mechanical devices have caused great problems in sludge transportation and disposal. Herein, coagulation and flocculation are combined with the use of a magnetic field as a clean and low-energy physical treatment method to enhance the dewaterability of municipal and citric acid–processing WAS. It is shown that the use of the magnetic field had a significant effect on the capillary suction time (CST) of municipal WAS but not on the specific resistance filtration (SRF) and CST of the citric acid WAS. The differences in the magnetic field effects were due to differences in the sludge properties. For municipal WAS, the particle size decreased, the zeta potential remained unchanged, and the viscosity decreased, whereas in the citric acid WAS, the particle size increased, the absolute value of the zeta potential decreased, and the viscosity increased. In addition, these effects were also confirmed with studies of the water state and micro-morphology analyses. It is shown that the acidification of the municipal WAS and coagulation of citric acid WAS were likely the reasons for the enhancement of their dewaterability, respectively. This study confirmed that the use of a magnetic field combined with coagulation/flocculation may serve as an effective sludge conditioning method; however, the treatment conditions may vary with the sludge type.