Bacterial and parasitological surveillance of untreated and treated sewage in the city of Tunis

The concentration of faecal contamination test-germs in wastewater has been determined at the entrance and the exit of three purification plants. Investigation for salmonella in the affluents and effluents of the three treatment plants proved that the systems of purification do not permit complete elimination of pathogenic bacteria from wastewaters. Helmith eggs has been observed in raw and treated wastewaters. Compared to the biological intensive systems, the lagoon treatment is susceptible to produce effluent with the best bacteriological and parasitical quality.