Removal of nitrate and sulphate from biologically treated municipal wastewater by electrocoagulation

Abstract

The present investigation observed the effect of current density (j), electrocoagulation (EC) time, inter electrode distance, electrode area, initial pH and settling time on the removal of nitrate (NO3−) and sulphate (SO42−) from biologically treated municipal wastewater (BTMW), and optimization of the operating conditions of the EC process. A glass chamber of two-liter volume was used for the experiments with DC power supply using two electrode plates of aluminum (Al–Al). The maximum removal of NO3− (63.21 %) and SO42− (79.98 %) of BTMW was found with the optimum operating conditions: current density: 2.65 A/m2, EC time: 40 min, inter electrode distance: 0.5 cm, electrode area: 160 cm2, initial pH: 7.5 and settling time: 60 min. The EC brought down the concentration of NO3− within desirable limit of the Bureau of Indian Standard (BIS)/WHO for drinking water. Under optimal operating conditions, the operating cost was found to be 1.01$/m3 of water in terms of the electrode consumption (23.71 × 10−5 kg Al/m3) and energy consumption (101.76 kWh/m3).