Parasite removal by waste stabilisation pond in Burkina Faso, accumulation and inactivation in sludge

Parasite removal and low cost systems for wastewater treatment in small settlements and economically disadvantaged areas have become increasingly important requirements in developed and developing countries to safeguard public health from wastewater-associated intestinal diseases. The paper evaluates the occurrence and removal of protozoan cysts and helminth eggs from the wastewater in a series of three ponds (anaerobic, facultative and maturation) treating domestic wastewater in Burkina Faso. Entamoeba coli, Entamoeba histolytica and Giardia lamblia were found as protozoan cysts in raw wastewater admitted in the system. In terms of helminth eggs, Ascaris lumbricoides, Ancylostoma sp., Trichuris trichiura, and Trichostrongylus sp. were detected. The effluent of the maturation pond, after a total of 18 days cumulative retention time, did not contain detectable cysts or eggs.The paper evaluates also sludge accumulations and their content in protozoan cysts and helminth eggs in each pond after 4 years of operation. Sludge was found to contain protozoan cysts and helminth eggs at variable concentrations from pond to pond with a gradual decrease through the pond system: 120 cysts and 556 eggs/g dry weight in the anaerobic pond, 10 cysts and 40 eggs/g in the facultative pond, and 7 cysts and 12 eggs/g in the maturation pond. A similar trend was found for the viability of helminth eggs, with the exception of the maturation pond, where no viable eggs were found.

► Total elimination of helminth eggs and protozoan cysts in the effluent of three ponds in series.
► High concentration of parasites in sludge of anaerobic pond.
► Reduction of helminth eggs viability in sludge from pond to pond.
► A correlation between sludge age and Entamoeba coli cyst concentration was used to estimate the destruction rate of cysts in the anaerobic pond.