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 is-sues. A novel technology, hydrodynamic cavitation combined with ozone (HC + O-3), has attracted wide attention in wastewater advanced treatment, whereas the contaminants removal mechanism and transformation of dis-solved organic matter (DOM) were rarely reported. This study investigated the removal efficiency and mechanism of HC + O-3. 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 O(3 )dosage of 6.25 mmol/L. The synergetic coefficient of HC + O(3 )was 2.77. The removal of contaminants was the synergy of( 1)O(2), .OH and .O-2(-), 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 + O-3. Meanwhile, most DOM had decreased to low apparent relative molecular weight (LARMW) compounds. Additionally, the HC + O-3 effluent can reach the emission standard in 60 min for 8.07 USD/m(3). It can be concluded that HC + O-3 is an effective technology for the advanced treatment of industrial wastewater. This study will provide suggestions for the engineering application of HC + O-3.