Removal efficiency of faecal coliforms and helminth eggs was evaluated in a small wastewater treatment plant (WWTP) serving a population of 1,000. This system was formed by the association in series of a UASB reactor and four submerged aerated biofilters. The density of faecal coliforms and the count of helminth eggs were estimated in the liquid and solid phases of the system. Two different methods of disinfecting sludge were investigated: (a) chemical treatment with lime and (b) a physical treatment by pasteurisation. As expected, the association UASB + BF was very efficient at removal of helminth eggs from the final tertiary effluent, but coliforms were still present at high densities. Lime treatment and pasteurisation of sludge were very effective methods of disinfection and produced a sludge safe for final disposal.

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