Treatment of pharmaceutical wastewater by combination of electrocoagulation, electro-fenton and photocatalytic oxidation processes

Abstract

The wastewaters produced in many different operations in the pharmaceutical industry are considered as an environmental problem because of their hazardous and potential for impacts on the aquatic ecosystem. In this study, the treatment of pharmaceutical industry wastewater by combination of electrocoagulation (EC), electro-Fenton (EF) and photocatalytic oxidation (PcO) processes was investigated. Initially, EF or EC processes were applied to degrade and decompose recalcitrant organic pollutants and PcO was then sequentially carried out to remove total organic carbon (TOC) and mineralise remaining compounds from wastewater. The performance of sequential implementation of EC + EF, EC + PcO and EF + PcO processes was investigated by using different current densities, catalysts, reaction times and process order. The most effective degradation was observed in the 1 h EF using 5 mA/cm(2) pulsed current density and optimum Fe:H2O2 molar ratio as 1:10 and then 4 h PcO using 1.5 g/L TiO2 and 10 mM H2O2. Results of sequential treatment processes indicated 64.0 % Total Organic Carbon (TOC), 70.2 % Chemical Oxygen Demand (COD) and 97.8 % Biological Oxygen Demand (BOD5) reduction and the energy consumptions were also calculated as 1051.21 kW h/kg TOC at 1 h EF and 4 h PcO.