REMOVAL OF HELMINTH PARASITIC EGGS FROM WASTE STABILIZATION PONDS AT SHIMOGA

Abstract

Helminth ova removal rates from waste stabilization pond effluents under tropical conditions of Shimoga using both laboratory and field modal ponds was undertaken. The helminthes were removed to the tune of 100% from laboratory model batch system ponds within 15 days of detention time and it was only 65% in case of laboratory model continuos flow system ponds. The observation in field model ponds revealed an average 90% removal with 10 days retention time. A 100% removal can not be expected both in continuous flow system laboratory model and field pond systems as these receive daily fresh load of helminth eggs through influent sewage. The helminth ova are usally removed from waste stabilization ponds systems through sedimentation process. It is because the helminth eggs attached to the suspended solids and when these solids settle to the bottom, the eggs are also removed from pelagic water. In the present study eggs of 4 helminth species viz. Ascaris lumbricoides, Hymenolepis diminuta, Hymenolepis nana and Enterobius vermicularis were encountered. Their rate of ova removal in batch system ponds was 99%, 97.4%, 94.9% and 98.8% for respective species. Presence of these ova in the sewage water indicates the prevalence of infection in city population.