Helminths viability in sludge of an anaerobic pond: a case study at 2IE treatment plant in Burkina Faso

Wastewater treatment with stabilisation system ponds produce sludge which requires to be desludged after a certain time of accumulation. In developing countries, the reuse of sludge constitutes a large practice which constitutes a health risk that must be taken into account for a sustainable reuse strategic. One such risk is the dissemination of helminthiases. The aim of this study was to evaluate parasitological contamination of sludge accumulated in an anaerobic pond at the treatment plant of the international institute for water and environmental engineering (2IE) in Ouagadougou. The pond was investigated for sludge accumulation through a bathymetric survey and helminth eggs viability was evaluated after four years operation. The rate of sludge accumulation was determined to averages of 18.4 cm/year, and 0.037 m/capita year. Helminth eggs were reduced on an average by 90% in the anaerobic pond. Ascaris lumbricoides and Ancylostoma sp were the most common eggs present in the sludge after four years operation. The average concentration of helminth eggs was 536 eggs/gTS and theirs rates of viability ranged from 10.8% (47viable eggs/gTS) to 57.2% (1772 viable eggs/g TS), with an average rate of 36% (336 viable eggs/g TS). From a sludge depth and section study, eggs viability was found to be randomly distributed in the sludge layer.