Combined Biological and Advanced Oxidation Treatment Processes for COD and Color Removal of Sewage Water

Abstract

Wastewater (WW) generation is inevitable in rapidly growing and urbanizing societies resulting in significant damage to the quality and quantity of fresh water resources. The study was intended to harness the reuse potential of sewage WW using integrated wastewater treatment process. Composite sample of sewage WW was collected from inlet of sewage wastewater treatment plant. The WW sample was batch wise subjected to activated sludge process (ASP), ozonation, UV irradiation, H 2 O 2 oxidation and sand filtration separately for different time intervals (i.e. 0 to 60 min) and concentrations of H 2 O 2 (0.1 to 1.0 mlL -1 ), followed by the integration of all the processes at their optimum conditions. Batch experiments were performed in pyrex containers using 1.5L sample except for ASP that is 20L. Efficiencies were measured in terms of COD, color and TSS removal along with changes in pH and temperature. Biological diversity of WW was also determined using cultural techniques followed by biochemical tests. Color reduction was much higher and faster than COD in all the tested treatment processes. Ozonation was the fastest process to remove 78% color in 30 minutes however, ASP was more economical for the same efficiency but requires high hydraulic retention time (HRT). Increase in UV irradiation time reduced COD and color by 54 and 69% after 60min respectively. Sand filter efficiently removed 97% TSS with marginal reduction in COD. Integration of 4 hr ASP, 24 min ozonation and 10 min UV exposure with 1 ml L -1 H 2 O 2 dose yielded 98 and 100% COD and Color reduction respectively.