The ozone/peroxymonosulfate (O3/PMS) system has attracted widespread attention from researchers owing to its ability to produce hydroxyl radicals (•OH) and sulfate radicals (SO4•−) simultaneously. The existing research has shown that the O3/PMS system significantly degrades refinery trace organic compounds (TrOCs) in highly concentrated organic wastewater. However, there is still a lack of systematic understanding of the O3/PMS system, which has created a significant loophole in its application in the treatment of highly concentrated organic wastewater. Hence, this paper reviewed the specific degradation effect, toxicity change, reaction mechanism, various influencing factors and the cause of oxidation byproducts (OBPs) of various TrOCs when the O3/PMS system is applied to the degradation of highly concentrated organic wastewater. In addition, the effects of different reaction conditions on the O3/PMS system were comprehensively evaluated. Furthermore, given the limited understanding of the O3/PMS system in the degradation of TrOCs and the formation of OBPs, an outlook on potential future research was presented. Finally, this paper comprehensively evaluated the degradation of TrOCs in highly concentrated organic wastewater by the O3/PMS system, filling the gaps in scale research, operation cost, sustainability and overall feasibility.

Biochar is a widely available carbon-based material that has been used for soil remediation and sewage treatment. However, in recent years, biochar has received more attention as a conditioning agent to improve the dewatering performance of sewage sludge. The sludge from the secondary sedimentation tank of wastewater treatment plants has high microbial activity and poor dewatering performance, which poses a challenge to sludge dehydration. Biochar and modified biochar can be injected into sludge as a skeleton to effectively reduce sludge compressibility, increase permeability, and release bound water, thus improving the dewatering performance of sludge. In this review, the preparation and characteristics of biochar are described, the current methods of sludge dewatering and the properties of sludge are introduced, and the research on the application of biochar in sludge conditioning is summarized. In addition, the existing problems and future development directions of biochar in sludge conditioning are discussed.

The widespread use of bisphenol A (BPA) in industry has resulted in BPA contamination of water bodies and even endocrine-disrupting effects on organisms and humans through water transmission. Advanced oxidation processes based on sulfate radicals have received increasing attention due to their ability to efficiently degrade endocrine disruptors (including BPA) in water. In this study, powdered iron (Fe(0)) and ferrous sulfate (Fe(II)) were used as activators to activate persulfate (PS) for the degradation of BPA. The effects of the dosage of the activator, the concentration of PS, the concentration of BPA, the initial solution pH, and the reaction temperature on the degradation efficiency of BPA in Fe(II)/PS and Fe(0)/PS systems were investigated, and the kinetics of BPA degradation under different reaction conditions were analyzed. The results showed that the optimal conditions were [Fe(II)] = 0.1 g/L, [PS] = 0.4 mM, [BPA] = 1 mg/L, T = 70 °C and pH = 5.0 for the Fe(II)/PS system and [Fe(0)] = 0.5 g/L, [PS] = 0.5 mM, [BPA] = 1 mg/L, T = 70 °C and pH = 5.0 for the Fe(0)/PS system; both systems were able to achieve equally good degradation of BPA. The degradation of BPA in the Fe(II)/PS system satisfied the pseudo-secondary kinetic equation under varying PS concentration conditions, otherwise the degradation of BPA in both systems conformed to the pseudo-first-order kinetic equation.

Pipeline transportation has become an effective way to transport sludge from wastewater treatment plants due to its high transportation efficiency, low operating cost, and low environmental pollution. Before designing and optimizing the sludge-conveying pipeline, it is first necessary to analyze the rheological properties of the sludge. In this paper, activated sludge with varying volume concentrations (Cw) of 2.38%, 3.94%, and 5.39% was used as the research object. Under three temperature (T) conditions of 293 K, 298 K, and 303 K, the sludge concentration and temperature were investigated, and based on the results, a rheological model of activated sludge was established. The experimental results indicated that the upward and downward paths of the shear stress change curve were generally similar but did not overlap, and a hysteresis loop was formed between the two due to the characteristics of sludge shear thinning. The limiting viscosity of sludge with different concentrations increased with the increase in sludge concentration. This phenomenon was caused by the differences in the internal flocculent network structure of sludge with different concentrations and the different fluid flow effects. At different shear rates, the shear stress and sludge viscosity in the experiment decreased with the increase in temperature. The stability of the test sludge was weakened with the increase in temperature. Additionally, the viscosity of sludge decreased with the increase in shear rate and then stabilized, exhibiting shear thinning characteristics. The above rheological properties were described using the Bingham and Herschel–Bulkley models.