Search Results (3)

Aiming at the defects of the low mass transfer efficiency and large floor space of the traditional ozone process, a cross-tube ozone catalytic oxidation pilot plant was designed and developed. By implementing lateral aeration and a modular series configuration, the gas–liquid mass transfer pathways were optimized, achieving a hydraulic retention time of 25 min and maintaining an ozone dosage of 43 mg/L, which significantly improved the ozone utilization efficiency. During the pilot operation in an industrial park in Suzhou, Anhui Province, the average COD removal efficiency of the device for the actual biochemical tail water (COD 82.5~29.7 mg/L) reached 35.47%, and the effluent concentration was stably lower than 50 mg/L, which meets the stricter discharge standard. The intermediate products in the system were also analyzed by liquid chromatography–mass spectrometry (LC-MS), and the key pollutants were selected for degradation path analysis. Compared to the original tower process in the park, the ozone dosage was reduced by 46%, the reaction residence time was reduced by 60%, and the cost of water treatment was reduced to 0.067 USD, which is both economical and applicable to engineering. This process provides an efficient and low-cost solution for the deep treatment of wastewater in industrial parks, and has a broad engineering application prospect. Full article

In this study, a Mn-Ce/γ-Al₂O₃ catalyst with multiple active components was prepared through the doping–calcination method for advanced treatment of coal chemical biochemical treatment effluent and characterized by X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy, and BET analysis. In addition, preparation and catalytic ozonation conditions were optimized, and the mechanism of catalytic ozonation was discussed. The Mn-Ce/γ-Al₂O₃ catalyst significantly enhanced COD and total phenol removal in reaction with ozone. The characterization results suggested that the pore structure of the optimized Mn-Ce/γ-Al₂O₃ catalyst was significantly improved. After calcination, the metallic elements Mn and Ce existed in the form of the oxides MnO₂ and CeO₂. The best operating conditions in the study were as follows: (1) reaction time of 30 min, (2) initial pH of 9, (3) ozone dosage of 3.0 g/h, and (4) catalyst dosage of 30 g/L. The removal efficiency of COD and total phenol from coal chemical biochemical tail water was reduced with the addition of tert-butanol, which proves that hydroxyl radicals (•OH) played a leading role in the Mn-Ce/γ-Al₂O₃ catalytic ozonation treatment process of biochemical tailwater. Ultraviolet absorption spectroscopy analysis indicated that some conjugated structures and benzene ring structures of organics in coal chemical biochemical tail water were destroyed. This work proposes the utilization of the easily available Mn-Ce/γ-Al₂O₃ catalyst and exhibits application prospects for the advanced treatment of coal chemical biochemical tailwater. Full article

Conventional pretreatment and secondary biochemical treatment are ineffective methods for removing phosphorus from phosphorus-containing pesticide wastewater. In this study, coagulation-coupled ozone catalytic oxidation was used to treat secondary biochemical tailwater of phosphorus-containing pesticide wastewater thoroughly. The effects of the coagulant type, coagulant dosage, coagulant concentration, wastewater pH, stirring rate, and stirring time on the removal efficiency of chemical oxygen demand (COD), total phosphorus (TP), and chromaticity were investigated during coagulation. When the dosage of the coagulant PAFS was equal to 100 mg/L, the concentration of the coagulant, pH, stirring rate, and stirring time were 5 wt%, 8, 100 rpm, and 5 min, respectively, and the removal rates of COD, TP, and chroma in wastewater reached the maximum value of 17.6%, 86.8%, and 50.0%, respectively. Effluent after coagulation was treated via ozone catalytic oxidation. When the respective ozone dosage, H₂O₂ dosage, catalyst dosage, and reaction time were 120 mg/L, 0.1 vt‰, 10 wt%, and 90 min, residual COD and chromaticity of the final effluent were 10.3 mg/L and 8, respectively. The coagulation-coupled ozone catalytic oxidation process has good application prospects in the treatment of secondary biochemical tailwater from phosphorus-containing pesticide wastewater. Full article