AWWA ACE92158

Assessment of biofilm growth in the Vancouver water distribution over a three year period indicated that concentrations of free chlorine in the range of 0.4 to 0.5 mg/L would be an effective level of disinfection for control of the biofilm. However, coliform bacteria in the biofilm were considered to be a result, not a cause, of elevated coliform levels in the water column. Therefore, biofilm removal may not result in any improvement in water quality. Notwithstanding this conclusion, biofilm monitoring programs may still be warranted and may be facilitated through the enumeration of coliforms in the sand substrate of a simple and cost-effective biofilm sampling device (sediment bag) which could provide an alternative to conventional water quality sampling programs and/or to investigations into the nature of biofilm in distribution systems; for example, to assess the effects of disinfection. The initial objective of this study was to assess the impact of chlorination on the biofilm both in terms of its rate of accumulation and levels of total coliforms using metal coupons to mimic the pipe walls. However, as the study progressed, it became evident that a more practical and cost-effective biofilm sampling technique was desirable, hence the concept of a sediment bag sampler was explored.

Product Details

Published:

01/01/1992

ISBN(s):

0898676525

Number of Pages:

13

File Size:

1 file , 450 KB