Biologically treated industrial wastewater disinfection using the synergy of low-frequency ultrasound and H2O2/O3.

Biological wastewater treatment is mostly used in many industries to treat industrial influents. Treated water is consisting of an extremely high concentration of pathogenic microorganisms. Present work demonstrate the treatment of biologically treated sugar industry wastewater (BTSWW) using a low-frequency ultrasound (US). BTWSS consists of Enterobacter, Salmonella, and Escherichia Coli with a total coliform concentration of 2500 ± 300 CFU/mL. Experiments were performed using the individual effect of US, H₂O_2, and O₃ and the combined effect of US with H₂O₂, O_3, and H₂O₂ + O₃. The complete removal of total coliform was obtained for the synergy effect of US with H₂O₂ and O₃. The performance of the process was analyzed based on pseudo-first-order kinetic rate constant and synergy coefficient. The pseudo-first-order kinetic rate constant was 21.6 and 22.3 × 10^–2 min⁻¹ with a synergy coefficient of 2 and 1.9 for a combined effect of US with H₂O₂ and O₃, respectively. Another advantage of the synergy of US and O₃ was lower requirement of the initial dose of H₂O₂ (2.1 mM/L). The operational cost of the process was found to be $ 1.5 × 10^–2 /MLD. Highlights: • Complete microbial disinfection achieved in 20 min. • The pseudo-first-order kinetic rate constant: 22.3 × 10^–3 min⁻¹ and synergy coefficient: 2 for US + O₃. • The operational cost of $ 1.5 × 10^–2 /MLD for US + O₃ [ABSTRACT FROM AUTHOR]