Analysis of the biological stability of tap water on the basis of risk analysis and parameters limiting the secondary growth of microorganisms in water distribution systems

ABSTRACT The consequence of the lack of water stability is increased susceptibility in the distribution system to secondary microbial contamination of water and thus a threat to the health of consumers. In this study, three different water quality parameters including BDOC (biodegradable dissolved organic carbon), ∑ N inorg , and PO 4 3– were employed to assess and evaluate the risk of loss of biostability of tap water. The analysis was based on the operating data obtained from the water treatment plant (WTP) prior to the final disinfection process for which water is supplied from intake of drilling wells, what constitute the new approach in comparison with other study. In this work, two technological schemes in the WTP were analyzed, one conventional, which is represented as WTP c , and the other using a biologically active carbon filter (BAF), which is represented as WTP cf . The modified Kaplan and Newbold method was used in determining the BDOC content by using for this purpose colonized by autochthonous bacteria bioreactor with granular activated carbon. Results show that conventional water purification processes do not provide the effective elimination of biogenic substances and, in particular, BDOC and assimilable organic carbon, therefore it is recommended to apply BAFs, as its effectiveness in removal of various impurities and the ability to stop waterborne microorganisms is very high.