Bacteriological Assessment of Mula-Mutha River Water, Pune, Using the Most Probable Number (MPN) Method

Abstract

The present study aimed to determine the bacteriological quality of Mula-Mutha River in Pune, Maharashtra by enumerating total coliforms and faecal coliforms from five sampling stations, (one upstream, one in the mid city and three downstream stations) using MPN method. The multiple-tube fermentation method was used for analyzing water samples, which included presumptive testing in lactose broth, confirmation of total coliforms in Brilliant Green Lactose Bile broth, and detection of faecal coliforms in EC broth at an elevated incubation temperature. The results indicated that densities of coliforms were significantly higher at stations, downstream of the important urban drainage inflows or stations that were influenced by sewage, and then decreased to varying extents at downstream stations. However, the densities of the bacteria were still high in the city and downstream sites as compared to upstream site. Sixty-two percent of the sites were microbiologically impaired when compared to Central Pollution Control Board water-quality criteria. The spatial trend supported the idea that there was more faecal contamination down stream from urban inflow points, but would need targeted microbial source tracking analysis to be determinate. The study shows the usefulness of the MPN method as a practical approach for routine monitoring of urban river water bacteriology and the need for better sewage interception and treatment, as well as for the ongoing water quality surveillance.