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The recent COVID-19 pandemic has increased the use of disposable face masks (DFMs). Due to a lack of manufacturing and disposal guidelines, DFMs are among the most common solid wastes worldwide. Common masks are made of polypropylene, which releases (nano)microplastics into the environment as it ages, causing environmental problems. In this work, the mechanism of aging of DFMs under UV radiation is studied and also the interaction mechanism of three antibiotics (ciprofloxacin (CIP), sulfamethoxazole (SMX) and tetracycline (TC)) with the original and UV-aged (nano)microplastics of the mask is investigated. The results showed that aging caused more antibiotics to be adsorbed onto the mask (nano)microplastics, mainly due to the oxygen-containing groups on the surface of the aged-mask. The adsorption capacity of the different layers of the (nano)microplastic mask for antibiotics was in descending order: inner-layer > outer-layer > middle-layer. The adsorption affinity of new and aged mask (nano)microplastics for antibiotics followed SMX > CIP > TC, which positively correlated with the octanol–water partition coefficient (log Kow) of antibiotics. In general, the adsorption process of antibiotics on (nano)microplastics is mainly governed by membrane-diffusion and distribution mechanisms, and hydrophobic interactions regulate the adsorption process.

Industrial production is the main reason for excessive fluoride content in wastewater, and it is necessary to adopt economical and effective fluoride removal methods. Therefore, be aware of the existing form of fluorine and the formation mechanism of fluoride pollution, and based on the water purification agents, environmental functions, and material innovation, this overview focuses on the defluoridation mechanism, the advantages and disadvantages of precipitation and coagulation, adsorption, electrochemical technology, and membrane separation technology. In the actual process of treating fluoride-containing wastewater, appropriate methods should be adopted according to the different characteristics of the wastewater. This review describes the research progress of fluo-ride removal methods for fluoride-containing wastewater at home and abroad in recent years, further analyzes the advantages and technical bottlenecks of these methods, and looks ahead at the major development trends in the future to provide a reference for further research on treatment technology of wastewater with a high fluoride content.

Ever since the Gravity Driven Membrane (GDM) system was proposed in 2010 as an environmentally friendly and low-carbon water treatment technology, the search for an appropriate pre-treatment measure to combat the low stable flux and membrane fouling has been of great importance for the promotion and development of GDM systems. This review summarized the effects of pre-treatment measures (particulate adsorption, coagulation, oxidation) in existing reports on stable flux, membrane fouling and water quality of GDM systems. Based on the literature reports, the internal mechanism was classified. The effects of different pretreatment conditions on stable flux were evaluated by meta-analysis, and the optimal process conditions to maintain higher stable flux with different pretreatments were predicted. The analysis revealed that appropriate pretreatment selection could improve the performance of the GDM system by removing fouling by the pretreatment itself, reducing bacterial EPS emissions, producing smaller/more hydrophilic pollutant molecules, enhancing bioactivity and generating a looser membrane structure. Moreover, the investment and operating costs of GDM systems can be reduced through suitable pre-treatment measures, thereby expanding their application in decentralized water supply and wastewater treatment. Given the variability and uniqueness of water source conditions, this review aimed to guide the design of pretreatment measures in GDM systems to improve the efficiency of targeted treatment and promote its applicability.

Background: The Environmental Management System (EMS) is a unique way to developan environmental policy with adequate planning, including implementation, operation,checking, and management review. Objective: The main stages of the EMS encompass environmental policy, planning, implementation,evaluation, and review. Methods: A number of environmental standards (ISO 14000), which were drawn up by the internationalstandardization organization, form an essential part of an EMS. This management systemintroduces environmental management into the day-to-day functions, long-term operations, andresource management frameworks of the organization. Results: This overview provides important information about the role of the EMS in water resourcemanagement and the scope of the EMS in the water system. This management system isused as an instrument to promote sustainable development in society. Conclusion: This paper sheds light on the topic of a sustainable water environment. In addition,some recognized successful EMS systems were reviewed and illustrated. We believe this reviewprovides a guide to a fruitful water environment for successful urbanization planning.

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The water solubility and polymerizability of maleoyl chitosan (MCS) was significantly improved by introducing a maleoyl group into the chitosan chain and MCS is a promising monomer for preparing chitosan-based flocculants with good water solubility. In this study, MCS was grafted with acrylamide and diallyldimethylammonium chloride to prepared a cationic chitosan modified flocculant chitosan-graft-poly (acrylamide diallyldimethylammonium chloride) (PMAD) with excellent solubility by ultraviolet (UV)-induced copolymerization techniques. The effects of monomer concentration, the percentage of maleated chitosan, photoinitiator concentration and illumination time on the intrinsic viscosity, grafting efficiency and dissolution time of PMAD were investigated by single factor experiments. The optimal synthesis conditions were determined with monomer concentration 12.5%, MCS percentage 10%, cationicity 11.25%, photoinitiator concentration 0.3% and illumination time 120 min, proving that UV initiated method was benefited to improve water solubility of PMAD. PMAD prepared at the optimized condition has the optimal viscosity of 4,823.2 mg L–1, the grafting efficiency of 70.7% and the dissolution time of 75 min. At the same time, the synthesized products PMAD were characterized by infrared spectroscopy, scanning electron microscopy, H-nuclear magnetic resonance, thermogravimetric and X-ray diffraction techniques. The flocculation experiments of PMAD on algae-containing water showed that the flocculation performance of PMAD was remarkably higher than that of commercially available polyacrylamide and polyaluminum ferric chloride. The optimal removal rate of Chl a (81.2%), turbidity (94.9%), and algae cell concentration (99.7%) by PMAD was obtained at dosage of 40 mg L–1, pH value 8 and G value 500 s–1. The obtained zeta potential results proved that the main flocculation mechanism of PMAD was the function of adsorption bridging.

In this paper, highly efficient Ti-Ag/γ-Al2O3particle electrodes were prepared for efficient degradation of chloramphenicol (CAP) by using three-dimensional electrocatalytic technology. The effects of preparation factors, such as mass ratio of Ti/Ag, loading times, and calcination temperature, on the electrocatalytic performance of Ti-Ag/γ-Al2O3particle electrode were investigated. In addition, Ti-Ag/γ-Al2O3particle electrodes under different conditions were characterized by SEM, EDS, XRF, and XRD. The optimal removal rate of chloramphenicol was 84.2% with initial concentration of chloramphenicol 100 mg/L, conductivity 6,000 μs cm–1, initial pH 4.0, current intensity I = 0.2 A, and flow rate 1.0 L/min. The elimination of •OH by addition of t-butanol reduced the chloramphenicol removal rate by 56.0% under the same working conditions, indicating that the degradation of chloramphenicol was caused by the combination of •OH indirect oxidation and anodic indirect oxidation. Meanwhile, the degradation process of chloramphenicol was approximately in accordance with the first-order kinetic equation.

In this work, carboxylated chitosan and acrylamide are used to synthesize a graft-modified natural polymer flocculant carboxylated chitosan-graft-acrylamide (CCSPAM) by UV-induced polymerization for copper and chromium removal. The effects of total monomer concentration, monomer mass ratio, pH value, photoinitiator concentration, and illumination time on the synthesis performance of CCSPAM were investigated regarding intrinsic viscosity (IV), grafting rate (GR), and grafting efficiency (GE). Various analytical techniques characterize the physicochemical characteristics of CCSPAM. Single factor experiments are used to investigate the effect of dosage, pH value, and reaction time on the chelation and capture of heavy metal ions by CCSPAM. The results show that the optimal IV, GR, and GE of CCSPAM achieved at total monomer concentration 30%, monomer mass ratio 1:4, pH 7.0, photoinitiator concentration 0.03%, and irradiation time 2 h are 1412.2 mL/g, 394.1%, and 84.1%, respectively. The experimental data of flocculation show that CCSPAM has a good total Cu and total Cr removal efficiency of 74.8% and 70.6% at dosage 2.0 mg/L, pH 6.0, and reaction time 2h, respectively. Fom the investigation, it is concluded that the grafted chitosan (CCSPAM) could be a be an effective and eco-friendly flocculant for removal of total Cu and total Cr ions from aqueous system.