Enhanced treatment of greywater using electrocoagulation/ozonation: Investigation of process parameters

Abstract

In current work, electrocoagulation (EC)/ozone process was applied for the treatment of greywater. The effects of several parameters were studied on chemical oxygen demand (COD) and total organic carbon (TOC) removals from greywater. The results showed that 85% of COD and 70% of TOC were removed during 60 min electrolysis time, at pH = 7.0, 47.4 mg/L ozone and 15 mA/cm2 current density. EC with Fe electrode exhibited high catalytic activity for ozone activation in contrast with Al electrode. According to the results, ozone had a superior compared to other chemical oxidant (peroxidisulfate, peroxymonosulfate and hydrogen peroxide) in combination with EC process for greywater treatment. UV irradiation improved the performance of EC/ozone considerably while ultrasound could not affect EC/ozone process. In the presence of UV irradiation, 95% of COD and 87% of TOC were eliminated. Moreover, 4 logs of total coliform and 96% of Escherichia coli were removed by EC/ozone/UV process. The calculated costs of EC/ozone and EC/ozone/UV were 1.9 and 4.03 $/m3 respectively. Hereupon, current system is an efficient and executable process for the treatment and disinfection of greywater.