Wastewater treatment by gamma radiation is a promising technology, with the capacity to reduce the impact of chemical and biological pollution of effluents in the environment. The aim of this study was to find out the effect of gamma radiation on the inactivation response of wastewater microorganisms. Wastewater samples were irradiated at a Co-60 facility, at different dose rates and at sublethal doses. The D10-values of total coliforms and mesophilic microbiota were determined for each sample and dose rate. Radio-resistant microorganisms in wastewater samples were isolated and their growth and inactivation kinetics in different composition substrates were determined, to find out the capacity of these bacteria to biodegrade the organic content of the wastewater. The results obtained suggest that irradiation substrate and dose rate influence the response of microorganisms to gamma radiation and could be also important factors for bioremediation.
Keywords: Coliforms; Dose rate effect; Gamma irradiation; Microbial inactivation; Substrate effect; Wastewater.