Application of ionizing radiation for sludge disinfection and its use for irrigation and fertilization

The sludge produced in the central, most populated area in Israel, is now dumped into the sea. Ionizing radiation was used to investigate the possibility of developing an industdal method for disinfection of the sludge, preparing it for use in farm land for irrigation and fertilization. A simple and inexpensive method for disinfection and preparing it for agricultural use is proposed. Sludge samples were irradiated with photons and electrons, it was found that relatively low radiation dose is enough to bring it to level A which is acceptable for the proposed use. Any dose of gamma radiation from a Co 60 source, from 0.2 Mrad and up, killed all coliforms in the sludge. Similar results were obtained for 3 MeV electrons. The irradiation stopped all biological activity in the sludge, therefore causing the solid part to separate from the water and sink. This stopped the gas (odor) emission from the sludge. The radiation did not have any effect on the heavy metals concentration in the sludge, but had some effect on the concentration of some of the light elements (some of it remained in the solid). The water, containing important minerals, was then tested fbr field irrigation. The product was tested for irrigation using droppers and found to be suitable.