Wastewater treatment is essential to prevent the environmental dissemination of waterborne pathogens. Fecal coliforms (FC) are the only indicator used to assess the microbial quality of the produced and utilized effluents. FC is more sensitive than viral and protozoan waterborne pathogens to disinfection. Therefore, alternative indicators such as coliphages were proposed. This study was performed to compare the removal of FC and F+coliphage by wastewater treatment processes. Furthermore, the suitability of qPCR for the detection of indicators in wastewater was evaluated. For coliphage detection, samples of secondary (20 L) and tertiary effluent (100 L) were collected. The treatment consisted of filtration and chlorination. Coliphages were eluted, and PEG reconcentrated. Coliphages and FC were detected by cultivation or qPCR. While the concentration of FC detected in secondary and tertiary effluents was 4.7x105cfu/100ml and 0.3cfu/100ml (removal of 6.2log10), no difference was observed for the levels detected by qPCR (removal of 0.77log10). Low removal (90%) of F+ coliphages was observed by tertiary treatment (9000 pfu/L were reduced to 839 pfu/L). The predicted concentration of coliphage was by two orders of magnitude lower than those detected by plaque assay, however, similar reduction values (79.1%) to plaque assay were recorded for the tertiary treatment. The results indicate the unsuitability of qPCR for the detecting FC in disinfected tertiary effluent. F+coliphage was found to be more resistant than FC to tertiary treatment suggesting that they are more suitable indicators for the removal of waterborne pathogens by tertiary treatment consisting of filtration and disinfection.
