Combined ultrasound cavitation and persulfate for the treatment of pharmaceutical wastewater

Abstract

In recent years industrialization has caused magnificent leaps in the high profitable growth of pharmaceutical industries, and simultaneously given rise to environmental pollution. Pharmaceutical processes like extraction, purification, formulation, etc., generate a large volume of wastewater that contains high chemical oxygen demand (COD), biological oxygen demand, auxiliary chemicals, and different pharmaceutical substances or their metabolites in their active or inactive form. Its metabolites impart non-biodegradable toxic pollutants as a byproduct and intense color, which increases ecotoxicity into the water, thus this requires proper treatment before being discharged. This study focuses on the feasibility analysis of the utilization of ultrasound cavitation (20 kHz frequency) together with a persulfate oxidation approach for the treatment of complex pharmaceutical effluent. Process parameters like pH, amplitude intensity, oxidant dosage were optimized for COD removal applying response surface methodology-based Box–Behnken design. The optimum value observed for pH, amplitude intensity and oxidant dosage are 5, 20% and 100 mg/L respectively with 39.5% removal of COD in 60 min of fixed processing time. This study confirms that a combination of ultrasound cavitation and persulfate is a viable option for the treatment of pharmaceutical wastewater and can be used as an intensification technology in existing effluent treatment plants to achieve the highest amount of COD removal. HIGHLIGHTS Synergistic effect of ultrasonication and persulfate oxidation studied on pharma wastewater.; Box–Behnken method applied for process parameter optimization.; Significant reduction in the COD from the pharma wastewater within one hour of the reaction.; Potential choice for the implementation of the process as a pre-treatment option for wastewater treatment.;

Keywords

• box–behnken design
• cavitation
• optimization
• persulfate
• pharmaceutical wastewater
• ultrasound