A Survey of Parasitic Contamination in Qasr-e-Shirin Raw Wastewater: the Role of a Constructed Wetland in Removing Contamination

The use of raw wastewater or effluent from inefficient wastewater treatment plants can result in an outbreak of parasitic diseases in a community. The aim of this study was to measure the parasite contamination of raw wastewater in Qasr-e-Shirin and evaluate the performance of a constructed wetland system in removing this contamination. This descriptive cross-sectional study was conducted over the course of 6 months (24 weeks), with a total of 48 samples selected to be tested. Every week a sample was taken from the raw wastewater of the influent and effluent. To identify parasites on the basis of a modified Bailenger method, parasitic analysis was conducted using a McMaster counting slide. The results showed that the minimum, average, and maximum number of all parasite eggs in the raw wastewater of Qasr-e Shirin was 0.08, 35.85, and 167.8 per liter, respectively. The minimum, average, and maximum number of protozoan cysts was 0, 19.95, and 75 per liter, respectively. In the wetland system of Qasr-e-Shirin, removal levels of protozoan cysts and parasite eggs were found to be 99.7 ± 0.23% and 100%, respectively. Because of parasitic wastewater contamination in Qasr-e-Shirin, outbreaks of parasitic diseases in this city are important issues. On the basis of the results of this study, constructed wetlands are very effective in removing parasitic contaminants. In addition, in term of parasite nematode eggs, the final effluent was consistent with the standards for reusing agriculture irrigation (1≥ number per L).