Characterization of NOM in the Han River and evaluation of treatability using UF–NF membrane

Abstract

Chlorine reacts with the natural organic matter (NOM) that remains in waters and forms halogenated by-products. Some of these products such as trihalomethanes (THMs) and haloacetic acids (HAAs) have been known to cause cancer and other toxic effects to human beings. Disinfection is a process for the inactivation of pathogenic microorganisms and prevention of waterborne diseases. Despite these advantages, disinfection needs to be evaluated and is of concern because of the serious risks to human health. Therefore, this study characterized NOM, which is a disinfection by-product (DBP) precursor, in the water treatment processes from the Han River and evaluated the removal efficiencies of NOM fractions by conventional and advanced processes. The raw water from the Han River contained higher hydrophilic fraction than the hydrophobic fraction. The hydrophilic NOM constituted still 55–70% of NOM in waters after each process. Since the hydrophilic NOM exhibited higher HAAFP than hydrophobic NOM, chlorination of the Han River water produced higher haloacetic acid formation potential (HAAFP) than trihalomethane formation potential (THMFP). When the fractions of DBPFP are expressed as percentage of total organic halide formation potential (TOXFP), THMFP, HAAFP, and others are 26%, 43%, and 31% of the TOXFP, respectively. UF membrane could replace conventional processes showing a little higher removal efficiency of NOM and DBPFP, but advanced processes will be required to meet future requirements. The ultrafiltration (UF)–nanofiltration (NF) combined membrane process had better removal efficiency of NOM compared to other processes. Therefore, the results of this study suggest that the UF–NF membrane process is one of the best available ways for removing NOM.