Integrated chemical treatment of municipal wastewater using waste hydrogen peroxide and ultraviolet light

Dilemmas like water shortage, rapid industrialization, growing human population and related issues have seriously affected human health and environmental sustainability. For conservation and sustainable use of our water resources, innovative methods for wastewater treatment are continuously being explored. Advance Oxidation Processes (AOPs) show a promising approach to meet specific objectives of municipal wastewater treatment (MWW). The MWW samples were pretreated with Al2(SO4)4·8H2O (Alum) at different doses 4, 8, 12–50 mg/L to enhance the sedimentation. The maximum COD removal was observed at alum treatments in range of 28–32 mg/L without increasing total dissolved solids (TDS). TDS were found to increase when the alum dose was increased from 32–40 mg/L. In the present study, the optimum alum dose of 30 mg/L for 3 h of sedimentation and subsequent integrated H2O2/UV treatment was applied (using 2.5 mL/L of 40% waste H2O2 and 35% fresh H2O2 separately). Organic and inorganic pollutants, contributing towards chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity and total dissolved solids were degraded by H2O2/UV. About 93% COD, 90% BOD and 83% turbidity reduction occurred when 40% waste H2O2 was used. When using fresh H2O2, 63% COD, 68% BOD and 86% turbidity reduction was detected. Complete disinfection of coliform bacteria occurred by using 40% H2O2/UV. The most interesting part of this research was to compare the effectiveness of waste H2O2 with fresh H2O2. Waste H2O2 generated from an industrial process of disinfection was found more effective in the treatment of MWW than fresh 35% H2O2.