Enhanced coagulation of disinfection by-products precursors in Istanbul water supply

Abstract

During the chlorination of drinking water, chlorine reacts with natural organic matter (NOM) to produce disinfection by-products (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), which are believed to be harmful to human health. Enhanced coagulation is a DBPs precursor treatment technique with the objective of removing total organic carbon (TOC) to control DBPs formation in water. Scientifically, the removal of organic matter by coagulation depends on the TOC concentration, the chemical nature of the NOM, coagulant type, coagulant dosage, and coagulation pH. Currently, water treatment plants are practicing enhanced coagulation to further increase DBPs precursor removal. The focus of this study was to investigate enhanced coagulation of Terkos Lake Water (TLW) of Istanbul City. In this study, jar test experiments were conducted on TLW source to determine the effectiveness of enhanced coagulation for removal of DBPs surrogate parameters of total organic carbon (TOC), ultraviolet absorbance (UV254), and THM formation potential (THMFP). jar tests results indicated that enhanced coagulation can increase the removal of DBPs precursors. To evaluate the coagulation performances, two different coagulants, aluminum and iron salts were used at different pH values to determine optimal coagulation conditions for surrogate parameters removal quantity.