Quantitative Microbial Risk Assessment of Giardia Cyst and Ascaris Egg in Effluent of Wastewater Treatment Plants Used for Agriculture Irrigation – a Case Study Publisher



Sharafi K¹ ; Pirsaheb M¹ ; Davoodi R² ; Ghaffari HR³ ; Fazlzadeh M⁴ ; Karimaei M² ; Miri M^{5, 6} ; Dindarloo K³ ; Azari A¹ ; Arfaeinia H⁷ Show Affiliations
Source: Desalination and Water Treatment Published:2017

Abstract

The aim of this study was to determine the concentration of Giardia cyst and Ascaris egg in influent and effluent of six wastewater treatment plants (WWTPs) in Kermanshah province, Iran, and to assess human health risk imposed by these organisms. Samples were taken from influent and effluent at weekly interval during 6 months. Samples were analyzed for Giardia cyst and Ascaris egg using McMaster egg counting technique according to Bailenger method. The Monte Carlo simulation method was used to calculate daily and annual infection risks. The efficiencies of all WWTPs to remove Giardia cyst and Ascaris egg from raw wastewater were more than 95%. However, maximum concentrations of these organisms were higher than acceptable level in some WWTPs effluents. Maximum concentration of Giardia cyst (2 counts/L) and Ascaris egg (4 counts/L) in effluent were observed in Kermanshah WWTP. The results of risk assessment indicated that annual infection risk related to both organisms were much more than acceptable level (10–4 pppy). Also, the imposed risk by Ascaris was higher than Giardia. There is a need for more precautions to be considered by farmers and other susceptible groups in contact to reclaimed wastewater in agricultural land, landscape and parks. Also, responsible organization should conduct more vigorous safety plans in site where WWTPs effluent is used for irrigation. © 2017 Desalination Publications. All rights reserved.