Kinetics of Electrochemical Disinfection of E. Coli in Ballast Water

Ballast water is used to maintain balance and structural integrity of ships. Therefore, ballast water is an essential component of the shipping industry. It has been found that the processes of ballasting and deballasting introduce unwanted living species to the coastal environments. Possible invasions create problems to the native environment, economy and human health. International Maritime Organization adopted a regulation to manage the transfer of invasive species through ballast water. In this research, an electrochemical disinfection reactor system is developed and used to disinfect E. coli; one of the regulated living organisms. Disinfection is studied at three different levels of initial E. coli concentrations, 10⁸, 10⁷ and 10⁶ CFU/100 ml. For the above initial concentrations, complete removal of E. coli is achieved within 150 s, 120 s, and 60 s while the energy consumptions are 0.0090 kWh/m³, 0.0074 kWh/m³, and 0.0035 kWh/m³, respectively. Kinetics of disinfection is developed for the abovementioned initial concentrations. It is found that the reaction rate constant is increased while the effect of chlorine concentration on disinfection is reduced with decreased initial E. coli concentration.

Key words: ballast water, chlorine, disinfection, E. coli, kinetics