Barrier role of wastewater treatment in wastewater disinfection with respect to E.Coli, generalized and total coliform bacteria

Abstract

Introduction. The work is devoted to the evaluation of the results of own studies of sanitary and microbiological pollution of wastewater in the cities of Moscow, Rostov-on-Don, Azov, Tsimlyansk and the analysis of literature data to justify the list of priority controlled sanitary and microbiological indicators of the safety of decontaminated wastewater that can be discharged into surface water bodies. Materials and methods. Wastewater was studied before and after entering the treatment plant over a 3-year period, including the determination of generalized and total coliform bacteria, sanitary indicative microorganisms, Klebsiella, Pseudomonas aeruginosa, Salmonella and their identification using the MALDI-TOF method and biochemical and serological properties. Results. The sewage waters of the studied cities entering the treatment facilities have a high degree of contamination by generalized and common coliform bacteria, salmonella, the intensity of pollution for which was within acceptable limits at the stage of discharge into surface water bodies according to SanPiN 1.2.3685-21. The number of generalized coliform bacteria exceeded the number of general coliform bacteria, both entering for disinfection and at the stages of purification and entry into surface waters, and their correlation with potentially pathogenic bacteria (PPB) and pathogenic salmonella, in contrast to total (lactose-positive) coliform bacteria, was revealed. Limitations. In the framework of the study, all isolated strains were identified and stored for the study of biological, genetic properties, taking into account the stages of purification, which will be the subject of further research. Conclusion. The index of generalized coliform bacteria retained its indicator significance in relation to pathogenic bacteria Salmonella spp. and made it possible to adequately assess the levels of bacterial contamination of wastewater. At the same time, the economic costs of determining the indicator of generalized bacteria do not differ from the costs of determining the indicators of common coliform bacteria and E. coli. Therefore, for the most adequate assessment of the disinfection of wastewater from treatment facilities, it is advisable to use generalized coliform bacteria as an integral indicator of Enterobacteriales bacteria.