Biofilms and bacterial drinking water quality

Abstract

Bacterial growth in potable water distribution systems was studied in a pilot reactor system designed to model the plug flow characteristics in a water main. Experiments were performed to measure specific cellular growth rates and numbers of cells growing on the pipe walls (biofilm cells) and cells suspended in the water phase (planktonic cells) to determine the relative contribution of biofilm accumulation to the bacterial populations in distribution mains. The experiments were performed with chlorine-free water at a water treatment plant as well as with disinfectant (chlorine) added to the reactor influent to examine the effect of chlorine on biofilm accumulation and planktonic cell numbers. The results indicate that biofilm growth and detachment accounted for most, if not all, the planktonic cells present in the bulk water of a chlorine free system. Chlorine affects the accumulation and spatial distribution of the biofilm.