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The authors provide the results of a study investigatingfactors affecting biofilm accumulation inbench-scale distribution systems using both syntheticand real waters. The effects were assessed bymeasuring the accumulation of heterotrophic platecount bacteria per unit area in an annular reactor. Theresults showed that the disinfectant residual was themost important factor in terms of controlling biofilm.The highest biofilm levels were observed under conditionsin which a high level of easily biodegradableorganic matter was present and there was no disinfectantresidual.Although a number of investigations have beenconducted to examine the formation of biofilms in bothreal and model distribution systems, there is relativelylimited information from controlled experiments thathave systematically investigated the various factorsinfluencing the extent of biofilm formation. Theauthors' purpose in conducting this research was toquantify the effects of the following factors: chlorine ormonochloramine residual, concentration of easilybiodegradable organic matter, shear (i.e., flow velocity),pipe material, and temperature.The results of this investigation have importantpractical implications for control of biofilms in distributionsystems. North American practice is generally tomaintain a residual in the distribution system, in partfor biofilm control. However, the results of this studysuggest that the residual should be defined based on avariety of factors and that interactions among the variousfactors are important in determining the extent ofdistribution system biofilm accumulation. Includes 29 references, tables, figures.

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Edition: Vol. 95 - No. 1 Published: 01/01/2003 Number of Pages: 11File Size: 1 file , 210 KB