AWWA ACE95078

AWWA ACE95078 Determining the Actual Amount of Biodegradable Organic Matter in Drinking Water Supplies
Conference Proceeding by American Water Works Association, 01/01/1995

Woolschlager, John; Rittmann, Bruce E.

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Accurately measuring the amount of biodegradable organic matter (BOM) in drinking water supplies is an important and timely topic. Studies have shown that the concentration of BOM is one of the major factors that promotes bacterial growth in distribution systems. Of course, it is essential to control distribution growth to meet regulations, especially the new rules ensuing from the Safe Drinking Water Act. Also, growth must be limited to avoid other bacterial induced problems, such as tastes, odors, decreased hydraulic capacity, and accelerated pipe corrosion. Although many tests have been developed to measure the amount of BOM in drinking water supplies, these tests often indicate a very different amount of BOM for similar water samples. Thus, water utilities are faced with the dilemma of which tests, if any, give an accurate indication of the true amount of BOM. Furthermore, many of these tests are difficult to perform and can require incubation periods of up to 30 days. The ultimate goal of this research is to help BOM testing advance toward a more accurate, rapid, and easy-to-perform test. All of these criteria must be met if a test is to be useful to water utilities. Advancements toward an improved test can only be obtained through an increased understanding of the fundamental kinetic principles involved in BOM testing, which is the specific objective of this modeling research. One important discovery from the modeling is that BOM test results cannot be related to the true amount of BOM without an estimate of the degradation kinetics of the BOM. As a result, the previously accepted idea that the biodegradable dissolved organic carbon (BDOC) or assimilable organic carbon (AOC) is an approximation of the true BOM appears obsolete. Also, varying the inoculum density can influence the results of BDOC tests. Using a low density inoculum for a hard-to-degrade substrate can seriously underestimate the amount of BOM in a sample.