Removal of turbidity, COD and BOD from secondarily treated sewage water by electrolytic treatment

A preliminary study was conducted for the removal of turbidity (TD), chemical oxygen demand (COD) and biochemical oxygen demand (BOD) from secondarily treated sewage (STS) water through the electrolytic batch mode experiments with DC power supply (12 V) up to 30 min and using a novel concept of electrode combinations of different metals. The different surface areas (40, 80, 120 and 160 cm2) of the electrodes as a function of cross-sectional area of the reactor and the effect of inter-electrode distances (2.5–10 cm) on the electrolysis of STS water were studied. This study revealed that the effluent can be effectively treated with the aluminum (Al) and iron (Fe) electrode combinations (Al–Fe and Fe–Al). The maximum removal of TD (81.51 %), COD (74.36 %) and BOD (70.86 %) was recorded with Al–Fe electrode system, while the removal of these parameters was found to be 71.11, 64.95 and 61.87 %, respectively, with Fe–Al electrode combination. The Al–Fe electrode combination had lower electrical energy consumption (2.29 kWh/m3) as compared to Fe–Al electrode combination (2.50 kWh/m3). The economic evaluation of electrodes showed that Al–Fe electrode combination was better than Fe–Al electrode combination. This revealed the superiority of aluminum as a sacrificial electrode over that of iron which can probably be attributed to better flocculation capabilities of aluminum than that of iron.