Examination of the behaviour of escherichia coli in biofilms established in laboratory- scale units receiving chlorinated and chloraminated water

Abstract

Groundwater was treated with chlorine and chloramine to study the incorporation and survival of Escherichia coli (E. coli) in developing biofilms in laboratory-scale units. Membrane filter and standard spread plate procedure were used to enumerate coliform and heterotrophic plate count bacteria respectively. Within 96 hours the adhesion of heterotrophic plate count bacteria on stainless steel coupons was obvious in all systems, with a higher number of organisms (4 log cfu cm-2) noted for the non-disinfected water. Attachment of E. coil added 24 hours after the formation of young biofilms was obvious on stainless steel coupons exposed to the non-disinfected water (9 cfu cm-2) and chlorinated water (2 cfu cm-2). A significant difference between E. coil counts in the non-disinfected water and chloraminated water, and the chlorinated and chloraminated water, was found. The ANOVA test indicated no significant difference in E. coil counts for the non-disinfected water and chlorinated water. This investigation revealed the effectiveness of chloramine in preventing the attachment of E. coil in developing biofilm, and in controlling the growth of attached heterotrophic bacteria