Under the dual pressures of climate change and urbanization, cities in China are experiencing increasingly severe flooding. Using the Yushan Lake area in Ma’anshan City, Anhui Province, as a case study, we employed the InfoWorks Integrated Catchment Management (ICM) hydraulic model to analyze the drainage and flood prevention system of the region and assess the current infrastructure for drainage and flood control. There are 117 pipelines with a return period lower than one year for stormwater and combined sewer systems, accounting for 12.3% of the total number of pipelines. The number of pipelines meeting the one-year but not the three-year return period standard is 700, representing 70.2%. Only 17.5% of the pipelines are capable of handling events exceeding the one-year standard. In simulating a 24 h, 30-year return period rainfall event, the results indicate that floodwater accumulation in the study area is predominantly between 0.15 m and 0.3 m. Most risk areas are classified as low risk, covering an area of 36.398 hectares, followed by medium and high-risk areas, which cover 8.226 hectares and 3.087 hectares, respectively. The Ma’anshan Yushan Lake area has, overall, certain flood control capabilities but faces flood risks during storms with return periods exceeding three years. This research offers valuable insights for improving urban flood management in Ma’anshan City through the development of a stormwater management model for the Yushan Lake area.

An in situ-generated MnO₂@SiO₂ colloidal (ISMC) composite was used for the adsorption of Mn²⁺ ions in water. The adsorption capacity of ISMC at a concentration of 1 mg/L at 25 °C was as high as 3017.97 mg/g for the original concentration of 50 mg/L Mn²⁺ ions. Material characterization revealed that it is a porous sponge with a fibrous structure with a rough surface, many folds, and abundant pores, and these features provide many adsorption sites, which are conducive to the attachment of Mn²⁺ ions on its surface. ISMC has an isoelectric point of 3.5, indicating a negative surface charge that favors electrostatic attraction of Mn²⁺ ions. The surface hydroxyl groups provide additional active sites that allow for strong complexation with Mn²⁺ ions. Adsorption conformed to the Freundlich isotherm model (R² > 0.98), suggesting multilayer adsorption, followed by pseudo-second-order kinetics (R² > 0.98), with an optimum adsorption time of approximately 12 h. Low temperatures favor physical adsorption, whereas higher temperatures promote chemisorption via hydroxyl group complexation. The adsorption capacity increased with pH, which was attributed to the increased presence of surface hydroxyl groups. These findings highlight the significant potential of ISMCs for cation adsorption in water treatment applications.

Ozone–activated carbon (O3/AC) systems are widely applied for the removal of soluble manganese (Mn(II)) in drinking water treatment. However, the underlying mechanisms remain poorly understood. In this study, the effects of granular activated carbon (GAC) and powdered activated carbon (PAC) on Mn(II) removal by O3 were systematically investigated. Mn(II) was rapidly removed by O3 alone (kobs = 0.069 s-1), whereas lower rate constants of 0.048 and 0.031 s-11 were observed in the O3/GAC and O3/PAC systems, respectively, at pH 7.0. Although increasing pH enhanced Mn(II) oxidation by O3 alone, the inhibitory effect of PAC became progressively stronger from pH 7 to 9. The inhibitory effects of GAC and PAC on Mn(II) removal were closely associated with enhanced O3 consumption, as demonstrated by O3 decay experiments. Although hydroxyl radicals (•OH) and superoxide radicals (O2•−) were generated in O3/GAC and O3/PAC systems, radical scavenging experiments demonstrated that these species contributed negligibly to Mn(II) oxidation. Overall, GAC and PAC enhanced O3 consumption and consequently reduced Mn(II) removal. These findings provide new mechanistic insights into the role of AC (especially PAC) in O3 oxidation for Mn(II) removal and contribute to a deeper understanding of combined O3/AC oxidation processes.

The efficient degradation of pharmaceuticals and personal care products (PPCPs), including diclofenac (DCF), in aquatic environments remains a major challenge. Recently, electrochemically activated permanganate (E-Mn(VII)) processes have been identified as a promising approach for organic pollutants treatment, although they exhibit relatively limited oxidation efficiency with conventional electrode materials. In this study, a novel E-Mn(VII) system was developed to overcome this critical bottleneck, where activated carbon (AC) was treated through simple mechanical ball milling and employed as a functional cathode material. Ball milling induced surface oxygen functionalities and structural defects in AC, thereby enhancing electrochemical generation of H2O2 from oxygen (O2) under acidic conditions. The ball-milled AC (BMAC) electrode produced a high H2O2 yield of 398.5 mg·L-1 and achieved a current efficiency of 80–84% after 120 min. The H2O2 generated in situ facilitated the transformation of Mn(VII) to MnO2 during electrochemical activation, serving as the primary catalyst to promote DCF removal by Mn(VII) oxidation. Consequently, DCF removal exceeded 86% within 30 min under optimal conditions with a pseudo-first-order rate constant (kobs) of 0.066 min-1, over 14 times higher than that observed by Mn(VII) oxidation. Radical scavenging and chemical probe experiments confirmed the negligible contributions of reactive oxygen species (e.g. •OH, O2•–, 1O2), and soluble manganese intermediates. The system maintained satisfactory performance in complex water environments and exhibited stable electrode recyclability. Overall, our research provides a rational strategy for enhancing electrochemical Mn(VII) activation by using mechanochemically modified carbon electrodes, advancing the development of efficient and sustainable E-Mn(VII) system for water decontamination.