Hybrid technology combining hydrodynamic cavitation and oxidative processes to degrade surfactants from a real effluent

This study evaluated the degradation of surfactants using hybrid technology that combined a hydrodynamic cavitation (HC), ozone (O 3 ), and hydrogen peroxide (H 2 O 2 ) reactor. The treated effluent was collected from an industry that produces tattoo ink. The HC device consisted of a plate with a 1.5 mm diameter hole. The effects of the initial pH (2.5, 4.5, 6.5, 8.5), inlet pressure (1.5, 3.0, 4.5, 6.5, 7.5 bar), O 3 load (0.6, 2.0, 3.1, 4.0 g h − 1 ), and initial concentration of H 2 O 2 (2.4, 7.1, 11.8 g L − 1 ) were investigated, applying a treatment time of 120 min. The results demonstrate that maximum surfactant degradation efficiency (37%), using HC alone, was achieved under acidic conditions (pH = 2.5) and an inlet pressure of 4.5 bar. Degradation efficiency was increased when O 3 was associated with HC, reaching 88.6% for injection of 3.1 g h − 1 of O 3 . The addition of an additional oxidant to the process (i.e., H 2 O 2 ) did not improve surfactant removal efficiency. On the contrary, a small reduction was observed. The present study demonstrated that the combination of HC with O 3 is a promising alternative for removal surfactants present in real effluents. However, more treatment stages are needed to remove carbonaceous organic matter, since the maximum efficiency of total organic carbon (TOC) removal from this effluent was 34%.