Validity of Primary Treated Wastewater for Irrigation and Assessment of their Potential Health Risk

Abstract

Samples of raw waste water is taken from the municipal sewer of Sumail district in Iraqi Kurdistan region and submitted to primary treatment by aeration to evaluate their validity for irrigation and potential health risks associated with this treated wastewater, Result revealed, (BOD) is improved by mechanical aeration, (COD) the aeration is not enough to bring it to safe ranges. Ammonia NH4 reduced by aeration from 24 to 18 mg/L as it converted to nitrite and nitrate by nitrifying bacteria in two-week period. the aeration removed about 2 third of TSS, TDS increase electrical conductivity of the water. TDS is reduced from 567 to 142 mg/l by aerating the water for 2 weeks. The content of heavy metal in all studied plants in almost cases are more than those irrigated by tap fresh drinking water. the content of essential micronutrients Mn, Cu, Fe and Zn in this study were elevated by treated wastewater, but all remain within the permissible limit in plant. Target hazard quotient (THQ) for cadmium in wheat is > 1 and the risks of cancer appearance in children is very high. Whereas the lead is worse than cadmium for children and the all studied plants has (THQ) >1 and associated with cancer risk in children if has been irrigated with wastewater or even treated wastewater.