Abstract:
Bacterial contamination in drinking water biofilm provides a potential source for
bacteria to grow and increase rapidly. To understand the microbial density in drinking
water distribution system (DWDS), a four month study was carried out. The aim of this
study was to examine biofilm in three different pipe materials including Polyvinyl
Chloride (PVC), Polypropylene (PPR) and Galvanized Iron (GI) in an educational
institution. A set of all these pipe materials was installed in DWDS at eight different
locations and analyzed after every fifteen days. Among different parameters measured,
dissolved oxygen, organic carbon and residual chlorine were found to be the main
indicators of microbial presence. Microbial identification made by molecular methods
of pathogenic detection (PCR based gene sequencing) detected Bacillus cereus strain
SH42, Lactobacillus crispatus ST1, Lactobacillus jensenii 269-3, Staphylococcus
aureus A9719, Paenibacillus sp. P22, Staphylococcus haemolyticus strain KJ1-5-97,
Pseudomonas sp. Lc31-4, Bacillus sp. BAB-3357, Paenibacillus sp. P22,
Achromobacter sp. BQNT2, Taylorella asinigenitalis and Tetrathiobacter kashmirensis
strain 3T5F as prominent species and their accession number were obtained from NCBI
(National Center for Biotechnology Information). Significant increase in bacterial
population was observed in GI pipes biofilm while least in PPR pipes. The quantity of
DWDS bacteria was directly depended on biofilm growth and its increase was
correlated with presence of organic matter on pipes. Pipe material also affected the
biofilm thickness while similarity in bacterial species was observed between system
due to same disinfectant dose, time period and plumbing pipes.
