(637f) Formation of Disinfection by-Products in Ballast Water Chlorination Process

Yue Ma, J. Paul Chen^*

Department of Civil and Environmental Engineering

National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore

^* Corresponding author. Tel.: +65 6516 8092; Fax: +65 6872 5483, +1 831 303 8636. Email addresses: jchen.enve97@gtalumni.org, ceecjp@nus.edu.sg(J.P. Chen).

Abstract

Chlorination has been proved as an effective option for minimizing and preventing the introduction of invasive marine species from ballast water. However, the formation of disinfection by-products (DBPs) would be a potential risk associated with the usage of chlorine as a biocide for ballast water treatment. The objective of this research is to access the formation potential of by-products, including four trihalomethanes (THMs) and nine haloacetic acids (HAAs) in seawater sample under different chlorination conditions likely to be encountered in ballast water disinfection system. The effects of chlorine concentrations, total organic carbon concentration and operation temperature on formation potential of DBPs were investigated. The decrease in UV absorbance at 254 nm (ΔA₂₅₄) and chlorine decay in the chlorination process were also monitored. It was determined that THMs predominated by bromoform while BDAA was the main HAAs component in all the samples studied. High fractions of bromo-deviation formed could be due to high amounts of bromide in seawater which is rapidly transformed by chlorine to hypobromous acid and other forms of bromine. Although the occurrence of DBPs in the investigated samples was higher than regulation amounts for treated drinking water, the environmental risk assessment showed the treated water would not pose great threats to the marine environment.

Keywords: By-products; Chlorination; Ballast water; Kinetics