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The goals of this powerpoint presentation were to: assess the impact of dynamic water qualityconditions on microorganism inactivation;identify the factors that affect themaintenance of a secondary disinfectantresidual, including the benefits of maintainingvarious target levels;determine the ability of a disinfectant residualentering the distribution system to inactivatemicroorganisms that may be encountered; and,assess the ability of a disinfectant residual toserve as an indicator for distribution systemmicrobial integrity. "Impact of Distribution System WaterQuality on Disinfection Efficacy" (AwwaRF / USEPA Project 2771) includes the following four phases:revisit existing information in the form of a literature review,a modeling effort,utility survey and historical water quality data analysis; determine inactivation potential (bench scale);evaluate the impact of acute and chronicwater quality changes on disinfection efficacy; and,examine analytical limitations of secondarydisinfectants (organochloramines). The goal of annular reactor testing is toassess efficacy of free chlorine andmonochloramine to inactivate suspendedand attached microorganisms.The objectives of annular reactor testing are to:determine target disinfectant residual topreserve water quality during simulatedmicrobial contamination;evaluate the impact of pipe material andwater age on water quality, disinfectionefficacy and biofilm production; and,examine the usefulness of flushing andincreased disinfection to remediatemicrobial contaminations. The experimental plan is presented, along with the results of the disinfection phases and pulse of E. coli. Presentation summary includes the following: Acclimation phase -- the upstream reactorof each train had the highest biofilmHPCs, followed by the middle reactor,and then the downstream reactor;Low-level disinfection phase -- biofilm HPCsdid not increase in the upstream reactors(disinfectant residual), but increased inthe downstream reactors;High-level disinfection phase -- suspendedHPCs at train effluent were lower;little effect on biofilm HPCs (increasewhen compared with acclimation phase); log reduction of suspended and biofilmHPCs was higher in the chlorinated trainsthan in the chloraminated trains withcomparable Ct values;monochloramine was more efficient thanfree chlorine against biofilm coliforms, butless efficient than free chlorine againstsuspended coliforms in the CI reactors;and, biochemical assays indicated thatcoliforms isolated from the bulk liquiddiffered from those isolated from thebiofilm of the same reactor. Includes figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 26File Size: 1 file , 1.2 MB