Efficiency of Helminth eggs removal in dewatered faecal sludge by co-composting

This study aimed at investigating helminth eggs removal efficiency in dewatered faecal sludge (FS) co-composted with organic solid waste as related to the turning frequency. A mixture of fresh public toilet sludge and septage mixed in a ratio of 1:2 was dewatered on a drying bed. Biosolids with initial load of 25-83 helminth eggs/g TS was mixed with solid waste as bulking material in a volume ratio of 1:2 for co-composting. Two replicate sets of compost heaps were mounted in parallel and turned at different frequencies: i) once each 3 days, ii) once each 10 days, during the active composting period, to study the influence of the operational conditions on the compost hygienic quality. The helminth egg removal efficiency was not different for the two turning frequencies. In both setups helminth eggs were reduced from 25-83 /g TS to a, < 1-3 viable eggs/g TS level, allowing a safety reuse in agriculture.