THMs REDUCTION IN WATER TREATMENT PLANT BY USING CHLORINE DIOXIED AS DISINFECTANT

The presence of trihalomethanes (THMs) in drinking water has attracted the attention of both researchers and professionals, because of the harmful effects of these substances on human health. Chlorine dioxide (ClO2) is an alternative to chlorine because it is an oxidizing agent rather than a chlorinating agent, and therefore, will not form chlorinated disinfection byproducts such as THMs under typical water treatment conditions. The study was conducted to determine the capability of ClO2 on the formation of THMs, and coliform bacteria. A small-scale pilot plant of a compact model is designed and constructed at Environmental Engineering Department laboratory (Babylon University).It is simple to operate and made of galvanized iron and locally available materials. Raw-water source is synthesized water preparation from tap water with average characteristics (pH 8.1, Turbidity 3.04 NTU, Alkalinity 150 mg/L as CaCO3, Temperature 17.5?C). Tap water was first passed through a tank and predetermined the concentration of turbidity and total organic carbon. Turbidity and TOC adjustment of water were finally performed by addition of natural clay screened for 200 μm containing leaves and stems of plants and other organic carbon to change the amount of turbidity and TOC of water. Characterizing of synthesized water was done at the Environmental lab of Babylon University. These characteristics are turbidity 27 NTU, alkalinity 140 mg/L as CaCO3, pH 8.22, temperature 28 ?C, and total organic carbon 1.4 mg/L Total Trihalomethanes (TTHMs), and their compounds and varieties of water quality parameters were monitored in the pilot plant, by the addition of different doses of chlorine dioxide and alum to synthesized water pipe entering the pilot plant and monitoring THMs concentration. The synthesizedand finished water quality parameters included; Hydrogen ion concentration, Temperature, Turbidity, Total Trihalomethane concentration.(HS ? GC - ECD) with Gas chromatography analysis techniques were used to measure the THMs concentrations. It was noticed that TTHMs concentration increases as temperature, and turbidity increase, and average TTHM levels detected in all runes not exceed the USEPA’s Stage I limit of 80 μg/L while it exceeded the limits in stage II for all sampling measurements.