Ferrate(VI) is a green and efficient water treatment agent for drinking and wastewater. It is widely used in water treatment because it has multi-functional uses such as oxidation, algae removal, disinfection, and adsorption flocculation. It does not cause secondary pollution to the environment. This paper compares ferrate(VI) with other water treatment agents and discusses three methods of preparing ferrate(VI). The removal, adsorption, and control of organic matter, algae, disinfection by-products, and heavy metal ions in water when ferrate(VI) was used as an oxidant, disinfectant, and coagulant were summarized. Ferrate(VI) has some advantages in removing toxic, harmful, and difficult-to-degrade substances from water. Due to the disadvantages of ferrate(VI) such as oxidation selectivity and instability, it is necessary to develop the hyphenated techniques of ferrate(VI). In this review, three hyphenated techniques of ferrate(VI) are summarized: ferrate(VI)–photocatalytic synergistic coupling, ferrate(VI)–PAA synergistic coupling, and ferrate(VI)–PMS synergistic coupling.

Perfluorinated compounds (PFCs) are recognized as a new type of refractory organic pollutants. Due to the persistent environmental pollution, bioaccumulation, and biotoxicity of PFCs, they have received extensive attention in recent years. To deal with the environmental risks caused by PFCs, the pollution and distribution of PFCs in the aquatic environment are discussed in detail, mainly for the most widely used PFCs—perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). The latest progress in the current processing technology of PFOA and PFOS is comprehensively introduced. It includes a variety of physical techniques to remove PFCs such as adsorption and flocculation. It has been confirmed that various adsorbents can play a key role in the enrichment and removal of PFCs through high specific surface area and hydrophobic interaction. In addition, traditional degradation processes are often unsatisfactory for PFCs, prompting the search for more efficient and cost-effective methods, with great progress having been made in advanced oxidation processes (AOPs) based on radical decomposition of pollutants. This review also integrates multiple advanced oxidation processes (AOPs) such as photocatalysis, electrochemical processes, ozone, the Fenton process, and ultrasound. This paper provides an overview of the various PFCs removal techniques and discusses their efficacy. It also explores future possible developments for PFCs elimination technologies for water treatment.

Azo dye wastewater is a common type of organic wastewater that often presents a significant challenge due to its gloomy color, high toxicity, and resistance to degradation. The discharge of such wastewater directly into natural water bodies can pose a severe threat to both ecological security and human health. Traditional biological treatment methods are often ineffective in treating industrial pollutants, but advanced oxidation technologies, such as persulfate (PS), offer unique advantages due to their strong oxidation ability and short reaction times. This study investigates the use of modified biochar (BC) material and catalyzed persulfate advanced oxidation technology to adsorb and separate acid orange 7 (AO7), a common industrial pollutant, from water and further oxidize and degrade it. Wood chips were used as biological templates to create an efficient, eco-friendly, and reusable adsorbent and catalytic material. In this paper, the adsorption effect of Fe₃O₄@BC on AO7 in water was compared, the adsorption kinetics and isotherm of Fe₃O₄@BC on different pollutants were studied, and the possible adsorption mechanism was proposed based on the relevant characterization. Adsorption kinetics describes the rate and quality of adsorption by studying the adsorption capacity in the adsorption process. Furthermore, the activated PS system was used to explore the degradation of AO7 at room temperature. First, the catalytic performance of Fe₃O₄@BC was evaluated by examining the amounts of PS and Fe₃O₄@BC, the initial pH, the ionic strength, and the reusability of Fe₃O₄@BC. Then, a possible degradation mechanism was proposed through electron paramagnetic resonance (EPR), free radical quenching experiment, and density functional theory (DFT) analysis. The results of this study suggest that modified biochar material and catalyzed persulfate advanced oxidation technology offer an effective and eco-friendly method for treating AO7 in wastewater.

Under the background of increasingly serious global environmental pollution, ensuring the safety of drinking water has become one of the focuses of global attention. In this study, Meihu Reservoir, a drinking water source, was selected as the research object, and the main pollution problems and their sources were revealed through conventional water quality analysis, suitability evaluation of the drinking water source and eutrophication evaluation of the reservoir. Using modern water quality monitoring technology and methods, the paper monitors and analyzes various water quality parameters of the Meihu Reservoir. The results showed that the water quality indexes, except total nitrogen, met the class II–III standard of drinking water, and the comprehensive nutrient state index method (TLI) evaluated the reservoir, and its index met $30\le \mathrm{TLI}(\sum )\le 50$, indicating that the reservoir belongs to the medium nutrition category. Therefore, the water quality of the reservoir has been affected by different degrees of agricultural, domestic and livestock pollution, mainly reflected in the serious excess of the total nitrogen index (the peak has reached 2.99 mg/L). The results of the on-site investigation showed that the main sources of nitrogen in the reservoir included agricultural non-point-source pollution, domestic sewage pollution, domestic garbage pollution and livestock and poultry pollution, accounting for 50.09%, 23.99%, 14.13% and 11.80% of the total load, respectively. On this basis, this paper puts forward some countermeasures for pollution control in order to provide a scientific basis and practical path for water quality protection and improvement of the Meihu Reservoir and other similar reservoirs.