10] Biodegradable organic matter measurement and bacterial regrowth in potable water

Abstract

Publisher Summary This chapter presents the methods available to evaluate biodegradable organic matter concentrations in water, and describes and compares several bioassays commonly used in the drinking water field to assess the bacterial regrowth potential of waters. Because a high biodegradable organic matter (BOM) level is one factor related to bacterial regrowth, BOM removal should be emphasized during water treatment to improve water quality. There is a weak correlation between organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC) concentrations. The BDOC test attempts to identify the entire pool of BOM, including very labile constituents to slowly biodegradable molecules (requiring the successive steps of cell adsorption, exoenzymatic hydrolysis, and cell consumption), whereas the AOC test detects easily assimilable organic compounds. Because both tests emphasize different fractions of biodegradable organic matter, both parameters should be monitored when studying nutrient changes during water treatment and distribution. Because of a long incubation period, using the BDOC suspended bacteria method is not practical at a water utility. A water utility can use either the sand or bioreactor methodology, depending on its testing objectives. Both methods yield to a similar BDOC result. The BDOC sand measurement is recommended for a short study or a limited number of samples.