Application of Ionizing Radiation Effects on Physical, Chemical and Biological Properties of Effluent Wastewater

Organic matter and water resources are limited for agricultural soil cultivation in Iran. Thus, according to the shortage of these resources, application of sewage sludge and effluent has been suggested. Wastewater, sewage and sewage sludge depending on the source have a variety of microbial, organic and inorganic contaminations. So, using of modern methods for their disinfection and purification is necessary before their application. One of these methods is application of radiation to disinfect wastewater and sewage sludge. Possibility of using non-ionization ultraviolet (UV) and ionization of electron beam and gamma radiation exists for effluent disinfection. Different disinfection mechanisms of ionizing radiation (formation of hydroxyl, hydrogen, hydrated electrons free radicals and etc.) and non-ionization (directly attacks to the DNA of microorganisms and formation of photoproducts such as pyrimidine dimers) have caused that the non-ionization UV method depend on environmental factors such as suspended solids, oxidizable organic and inorganic substances, dissolved oxygen, pH, temperature and etc. The another disadvantages of UV compared to ionizing radiation could be mentioned as limitation of its using only for disinfection of secondary effluent, possibility microorganism’s regrowth inactivation and seasonal changes of disinfection efficiency. Sewage sludge can be disinfected only by using of ionizing radiation. Among ionizing radiations, gamma rays compare of electron beam have more benefits such as better penetration power, allowing thicker layers of sludge to be irradiated, and low lethal dose to remove pathogens which makes extensive use of it. Due to satisfactory results, use of ionizing radiation for the treatment and disinfection of wastewater, sewage effluent and sludge in worldwide, the results of this study emphasize on possibility of ionizing radiation application in the disinfection of wastewater, sewage effluent and sludge in Iran.