The advanced treatment of textile printing and dyeing wastewater by hydrodynamic cavitation and ozone: Degradation, mechanism, and transformation of dissolved organic matter

The emission standards for textile printing and dyeing wastewater are stricter due to serious environmental issues. A novel technology, hydrodynamic cavitation combined with ozone (HC + O3), has attracted wide attention in wastewater advanced treatment, whereas the contaminants removal mechanism and transformation of dissolved organic matter (DOM) were rarely reported. This study investigated the removal efficiency and mechanism of HC + O3. The maximum removal rates of UV254, chrominance, CODCr, and TOC were 64.99%, 91.90%, 32.30%, and 36.67% in 60 min, respectively, at the inlet pressure of 0.15 MPa and O3 dosage of 6.25 mmol/L. The synergetic coefficient of HC + O3 was 2.77. The removal of contaminants was the synergy of 1O2, ·OH and ·O2-, and high molecular weight and strong aromaticity organic matters were degraded effectively. The main components in DOM were tryptophan-like and tyrosine-like, which were effectively removed after HC + O3. Meanwhile, most DOM had decreased to low apparent relative molecular weight (LARMW) compounds. Additionally, the HC + O3 effluent can reach the emission standard in 60 min for 8.07 USD/m3. It can be concluded that HC + O3 is an effective technology for the advanced treatment of industrial wastewater. This study will provide suggestions for the engineering application of HC + O3.