A Comparison of the Efficiency of Natural Wastewater Treatment Plants in Removal of Protozoan Cysts and Parasitic Eggs

One of the most important quality characteristics associated with wastewater reuse in agriculture, which takes into consideration, is the microbial quality. The aim of this study is determination of efficiency of wastewater treatment plants in removal of protozoan cysts and parasitic eggs of Ghasreshirin (constructed wetland), Islamabadgharb and Gilangharb (stabilization ponds). This study was accomplished during six months and sampling was done from inlet and outlet of wastewater Plants, as weekly. Totally, 144 samples were investigated for parasitic analysis with Bailenger method by Mac Master Slide (with a hole size 0.3 ml). The findings showed that mean of removal efficiency in constructed wetland for parasitic eggs and protozoan cysts are %99.7±0.23 and %100 respectively, but, any parasitic eggs and protozoan cysts in outlet effluent of both of wastewater stabilization ponds were not observed, so removal efficiency of these two parameters in these systems was %100 obtained. Ascaris lumbricoides eggs had most number of parasitic eggs in inlet wastewater and outlet effluent of all three wastewater treatment plants. According to the results, the efficiency of all three wastewater treatment plants in terms of removal of cysts and parasitic eggs are desirable and there was no significant difference between them (Pvalue>0.05). The outlet effluent quality of them in terms of nematode eggs rate is consistent with Engelberg index (number of nematode eggs: 1 ≥ number per liter).