Application of ozone combined technology in industrial wastewater treatment

The treatment of pharmaceutical wastewater typically involves high COD levels and poor biodegradability. Purely relying on physicochemical methods for treatment is costly and uneconomical, while conventional biochemical treatment simply does not work. Therefore, ozone pretreatment can be employed first, primarily to enhance the biodegradability of the wastewater, reduce the difficulty for subsequent biological treatment, and simultaneously lower the COD.
The treatment of printing and dyeing wastewater is crucial due to its severe environmental pollution. This type of wastewater is characterized by its large volume, significant fluctuations in water quality, complex and high concentrations of pollutants, and high chromaticity, chemical oxygen demand (COD), and biochemical oxygen demand (BOD). It is one of the most difficult industrial wastewaters to treat both domestically and internationally. Ozonation technology utilizes the strong selectivity of ozone molecules to directly undergo addition reactions with dyes containing double bonds, resulting in ring-opening decolorization of the dyes and enhancing the biodegradability of the wastewater. Furthermore, under ultraviolet (UV) radiation, ozone is converted into strong oxidizing substances such as ˙OH, which react with organic compounds, breaking the unsaturated bonds in the chromogenic groups of the dyes and generating small, colorless organic acids, aldehydes, etc., thus achieving decolorization and degradation of organic matter. By combining O3/UV oxidation with conventional biochemical treatment, most of the biodegradable organic matter is removed through biochemical methods first, and the remaining non-biodegradable pollutants are treated with O3/UV oxidation. This approach reduces ozone consumption and treatment costs while improving the quality of the effluent.
The treatment of phenol-containing wastewater is one of the more common and highly hazardous types of industrial wastewater. Phenol is a recognized "carcinogenic, teratogenic, and mutagenic" substance, and the treatment of industrial phenol-containing wastewater is one of the urgent issues in the field of industrial wastewater. Studies have shown that for coking plant wastewater with a phenol content of 227mg/L, a pH value of 7.3-7.6, and a water temperature of 13-40°C, after ozonation treatment, the phenol content in the water is reduced by 98%.