Effectiveness of removing microbial pollutants from wastewater by the activated sludge method

Wastewater contains numerous saprophytic microorganisms, pathogenic and potentially pathogenic. Detection of bacteria indicating the sanitary state of polluted waters shows the possibility of occurring of pathogenic microorganisms in that environment. In the presented paper, the effectiveness of removing microbiological pollutions from wastewater treated by the activated sludge method has been evaluated, by estimating the elimination of E. coli, faecal streptococci, rods of the genus Salmonella and bacteria of the family Enterobacteriaceae. Experimental research showed that often in spite of a high degree of elimination of bacteria at individual stages of treatment, they are still identified in wastewater discharged to the water environment. The fact of occurring bacteria of the family Enterobacteriaceae and rods of Salmonella in treated wastewater discharged to surface waters is particularly worrying.