Measurement of bacterial growth potential in a reclaimed water

The objectives of this paper are to show a bio-assay method using direct total microbial count (DTMC) and to demonstrate the applicability of this method to reclaimed water for evaluating its potential of bacterial growth. We have applied our method to four types of reclaimed water, measuring the time course of DTMC and dissolved organic carbon in a bio-assay process. The experimental findings are summarised as follows: 1) By regulating organic carbon, bacteria growth could be controlled. 2) Reduction of the initial concentration of bacteria was effective to delay their growth, but this operation could not control their maximum level. This implies that the retention time of the storage and distribution system of reclaimed water should be considered in design and operation of the disinfection process. 3) Ozonation increased the growth potential. Carbon adsorption process reduced it, but the ozone plus carbon adsorption process could not improve the biological stability. 4) A linear relationship between DTMC and biodegradable organic carbon has been observed, the gradient of this linear correlation, however, depended on the source of reclaimed water.