Remediation of raw sewage water by ionizing radiation

Raw sewage water has been used for irrigation in many countries in the world including Egypt. Although the reuse of sewage water for irrigation has become essential, this practice could represent a hazard to the environment and human health. Radiation treatment was applied to test its effect on the remediation of raw sewage water collected from the inlet of El-Gabal El-Asfar Waste Water Treatment Plant, north east of Cairo city. Different doses of gamma radiation and electron beam ( 0.5, 1.0, 1.5, 2.0, 2.5 KGy) were tested for their effects on raw sewage water properties. The parameters tested were total Coliform, BOD, COD, TSS, ph, EC, heavy metals, NH4 and NO3. The data showed an inverse relationship between radiation dose and total Coliform, BOD, COD and TSS. This result proved true for both kinds of radiations. However, the effect of gamma radiation was more pronounced than the electron beam at the same dose. The lethal doses for total Coliform were 1.5 KGy and 3.0 KGy for gamma radiation and electron beam, respectively. Regarding ammonium and nitrate ions, there was a reduction in their content as the radiation dose increased. The reduction was 20% for NH4 and 21% for NO3 at 2.5 KGy dose using gamma or electron beam, respectively. The total heavy metals levels were 40.0, 5.8, 55.9, 0.55, 32.2 and 16.4 ppb for Ni, Co, Cu, Cd, Pb and Zn. The soluble fraction were 19.5, 3.3, 8.3, 0.02, 0.50, 3.1 ppb representing 49%, 58%, 15%, 3%, 1.6% and 19% of the total Ni, Co, Cu, Cd, Pb and Zn, respectively. In general, there was a tendency for reduction of the soluble fractions of heavy metals as the radiation dose increased