Ascaris removal and inactivation in FS using vermifiltration (South Africa)

This research sought to not only understand the removal and inactivation possibilities of vermifiltration, but also to understand the general fate of Ascaris eggs. The experimental work was carried out using three identical laboratory set- ups (vermifilters) in Durban, South Africa. During the study, 1475 gr of faecal sludge and 290,457 Ascaris eggs were added in each vermifilter (VF) over five- weeks’ experiment. The research demonstrated that the removal and inactivation efficiencies of the vermifiltration process were 91 % and 73 %, respectively. Additionally, of the 290,457 Ascaris eggs added into the VFs, an average of 5,490 (1.9 %) and 21,784 (7.5 %) eggs were found in the VF as viable and non-viable, respectively. Out of the 21784 non-viable Ascaris eggs found in the VFs, an average of 14,430 (up to 66 %) were inactivated but not removed as a result of vermifiltration. The inactivation could be due to the crushing and enzymatic actions from the earthworms. The study concluded that even when the removal efficiencies are high, effluent and vermicompost may pose health threats as a result of high Ascaris eggs (more than the set WHO standard). Therefore, further treatment needs to be done before reuse of the FS residue. It was recommended that vermifiltration, as a FS treatment option, can be adopted as a small-scale decentralised system.