A STUDY ON THE QUALITY OF DRINKING WATER DISINFECTION IN SMALL SETTLEMENTS FROM STARA ZAGORA REGION, BULGARIA

Gergana Sandeva, Nikolay Sandev, Rositsa Deliradeva, Pavlina Gidikova, Magdalena Platikanova

Abstract


Introduction: Providing safe drinking water is an integral part of public health and a major task for water supply companies and health control agencies alike. Poor quality disinfection of drinking water significantly increases the risk of water-borne epidemics. In Bulgaria, villages and small towns are affected more often by failures in the disinfection due to negligence from water supply employees and technological limitations. Aims: To determine the quality of drinking water disinfection by measuring significant indicators (free chlorine, E.coli and coliforms) in samples from villages in Stara Zagora region. Materials and Methods: Water samples were taken according to protocol directly from water taps in 50 villages in Stara Zagora region. Levels of free chlorine were measured using HACH DR/850 colorimeter and compatible reagents. 100 mL samples were inoculated with the medium Readycult®Coliforms 100. The samples were incubated in a thermostat at 37°C for 24 hours and E.coli were identified using Kovac’s reagent. Results: Only in 5 samples (10%) free chlorine was adequate to the established norm of 0.3-0.4 mg/L. In 30 villages the levels of free chlorine were below 0.3 mg/L and cannot guarantee drinking water safety. In 15 villages (30%) were found coliforms above the acceptable norms (0/100 mL). Nine of these samples were positive for E. coli. Conclusion: The results showed significant deviation from the legally established norms for drinking water safety. More tests will be done to determine whether these problems are incidental or permanent.


Keywords


indicator bacteria; water pollution; drinking water safety

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DOI: http://dx.doi.org/10.15835/buasvmcn-agr:11153


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