Junlian Qiao

Pharmaceuticals such as diclofenac (DCF), a widely used anti-inflammatory drug, are frequently detected in water bodies and pose serious environmental and health risks due to their persistence and low biodegradability. Although ozonation is an effective method for pollutant removal, its efficiency is often limited by low ozone utilization and incomplete mineralization. In this work, CuO/Al₂O₃- and MnO₂/Al₂O₃-supported catalysts were prepared via an impregnation method and evaluated for their performance in catalytic ozonation of diclofenac (DCF) in an aqueous solution. The catalysts were characterized by TEM, N₂ adsorption–desorption, FTIR, and XPS analyses. The effects of catalyst type, dosage, initial pH, and ozone flow rate on degradation efficiency were systematically investigated. Under optimal conditions, the DCF removal efficiencies reached 73.99% and 76.33% using CuO/Al₂O₃ and MnO₂/Al₂O₃, respectively, while COD removal efficiencies were 77.6% and 89.3%. Quenching experiments indicated that hydroxyl radicals (•OH) were the predominant reactive species involved in the catalytic ozonation process. The results demonstrate that supported CuO and MnO₂ catalysts can effectively enhance diclofenac degradation by ozone, offering potential for advanced water treatment applications.

Since the observation that carbon materials can facilitate electron transfer between reactants, there is growing literature on the abiotic reductive removal of organic contaminants catalyzed by them. Most of the interest in these processes arises from the participation of carbon materials in the natural transformation of contaminants and the possibility of developing new strategies for environmental treatment and remediation. The combinations of various carbon materials and reductants have been investigated for the reduction of nitro-organic compounds, halogenated organics, and azo dyes. The reduction rates of a certain compound in carbon-reductant systems vary with the surface properties of carbon materials, while there are controversial conclusions on the properties governing the catalytic performance. This review scrutinizes the contributions of quinone moieties, electron conductivity, and other carbon properties to the activity of carbon materials. It also discusses the contaminant-dependent reduction pathways, i.e., electron transfer through conductive carbon and intermediates formed during the reaction, along with possibly additional activation of contaminant molecules by carbon. Moreover, modification strategies to improve the catalytic activity for reduction are summarized. Future research needs are proposed to advance the understanding of reaction mechanisms and improve the practical utility of carbon material for water treatment.

In recent years, China has been vigorously carrying out the planning and implementation of Sponge City. Since the implementation of Sponge City projects involves substantial materials and energy consumption, it is significant to account corresponding carbon emissions and sinks. The existed studies about carbon emission of stormwater management measures, however, are not able to take the whole life cycle and different facilities into consideration. Therefore, this study develops a comprehensive accounting model based on Intergovernmental Panel on Climate Change (IPCC) guidelines and life cycle assessment (LCA) method to predict carbon emissions and carbon sinks of Sponge City projects more comprehensively and accurately. The model is applied to an actual residential community in Shanghai as a case study. Results show that the total indirect carbon emission is estimated to be 774,277 kg CO₂ eq during a 30-year lifespan, among which carbon emissions from operation and maintenance phases are 2570 kg CO₂ eq/year and 7309 kg CO₂ eq/year, respectively, both directly proportional to the service life of the facilities. Three kinds of achievable carbon sinks are carbon sequestration in green space (5450 kg CO₂ eq/year), carbon sink from rainwater utilization (15,379 kg CO₂ eq/year) and carbon sink from runoff pollutant removal (19,552 kg CO₂ eq/year). Carbon neutrality is expected to be reached after approximately 19 years. The established carbon emission accounting model can contribute to better planning and construction of Sponge City in China and enhance further energy conservation and carbon emission reduction.

Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1 h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.

A magnetic propeller agitator and a magnetic reactor were designed to enhance the removal of heavy metals by zerovalent iron (ZVI) in comparison with the non-magnetic reactor. The weak magnetic field (WMF) applied significantly improved the CuII-EDTA removal by ZVI from 10% without WMF to 98% with WMF within 2.5 h at pHini 6.0. The pseudo-first-order rate constants of Cu(II) and As(V) removal by ZVI in the magnetic reactor were increased by 1.51–5.17 and 2.97–5.91 fold, respectively, compared to those obtained in the non-magnetic reactor. The performance of ZVI for treating practical industrial wastewater in the designed magnetic reactor was tested, and the removal of total Cu, P and Zn by ZVI was greatly accelerated. After precipitation of the practical wastewater samples, the concentrations of total Cu, P, Zn decreased to the industrial drainage standard values in 20, 3, 25 min, respectively, in the magnetic reactor, whereas the reaction time needed to eliminate total P and Zn was 10 and 60 min, and the residual total Cu still exceeded the drainage standard values in 2 h in the non-magnetic reactor. The application of magnetic reactor for industrial wastewater treatment is expected to improve the sustainability of ZVI technology.

The combined application of polydiallyldimethylammonium chloride (PDADMAC) and polysilicate aluminum ferrite (PSFA) was investigated to treat low algae density water samples, in which Microcystis aeruginosa is one of the dominant species. coagulation performance of M. aeruginosa was studied with regard to algal removal, Algal density was evaluated by determining the change in the optical density of the algal culture suspension at 680 nm and chlorophyll a. The dissolved organic matter, cellular morphology, viability, and recovery of M. aeruginosa cells after flocculation and sedimentation were also included. In addition, the effects of pH and addition order of PSFA and PDADMAC on algal removal were investigated. The removal efficiency of algae coagulated using combined PDADMAC and PSFA was improved by 34.5% and 19.3%, respectively. The organic matter removal was also enhanced. The optimum pH range for algal removal is 7.0–10.0, and the preferable addition sequence is the simultaneous addition of PDADMAC and PSFA. Scanning electron microscopy observation indicated that the combined usage of PDADMAC and PSFA caused no damage to the algal cell. Moreover, the experiment on algal recovery demonstrated that PDADMAC has bacteriostatic ability.