Elimination of enteroviruses, other enteric viruses, F-specific coliphages, somatic coliphages and E-coli in four sewage treatment plants of southernGermany

The reduction processes at four advanced sewage treatment plants in Baden-W urttemberg were evaluated with regard to virus elimination and the eliminat ion of indicator organisms from wastewater. The results of virus eliminatio n were compared with the reduction of somatic and male specific bacteriopha ges and of E. coli. In total, 222 water samples were examined. The results obtained for the different treatment plants show reduction rates from 80.0% to 99.9% for enteroviruses, enumerated as PFU I-1 on BGM cell line and red uction rates from 59.4% to 99.9% for other enteric viruses, enumerated as M PN I-1 on MA-104 cell line. Identification of the isolated enteroviruses yi elded 88.3% for Coxsackie virus B (1-5), 18.3% were positive for Polio (1-3 ) and 8.3% for Echo virus (1+11). The reduction rates of somatic bacterioph ages ranged from 76.4% to 99.90%, for male specific bacteriophages from 87. 5% to 99.9% and for E, coli, from 75.0% to 99.9% respectively. Two of the p lants use standard chemical precipitation and the other two employ combinat ions of chemical and biological elimination techniques to reduce the concen trations of phosphorus and nitrogen. A correlation between the amount of pr ecipitators and the elimination rates of the tested microorganisms could no t be demonstrated, perhaps due to the fact that the treatment conditions co uld not be modified by the investigators. It is concluded that the tested t reatment plants using combinations of chemical and biological techniques fo r P and N removal show equal or higher elimination rates than conventional treatment processes using chemical elimination techniques.