Hamid Mohammad Al-Gabra, Tianling Zhengb,Xin Yua,Science of the Total Environment, 2013. 463–464:525– 529

The disinfection process for inactivating microorganisms at drinking water treatment plants is aimed for safety ofdrinking water for humans from a microorganism, such as bacteria, viruses, algae, fungi by using chlorination,ozonation, UV irradiation, etc. In the present study, a combination of two disinfectants, UV irradiation followedby chlorination, was evaluated for inactivating Aspergillus flavus under low contact time and low dosage of UVirradiation. The results indicated an inverse correlation between the inactivation of A. flavus by using UV irradiation only or chlorination alone. By using UV radiation, the 2 log 10 control of A. flavus was achieved after 30 s ofirradiation, while chlorination was observed to be more effective than UV, where the 2 log was achieved at chlorine concentration of 0.5, 1, 2 and 3 mg/l, in contact time of 60, 5, 1 and 1 min, respectively. However, combineduse (UV irradiation followed by chlorination) was more effective than using either UV or chlorination alone; 5 sUV irradiation followed by chlorination produced 4 log 10 reduction of A. flavus at chlorine concentrations of 2 and3 mg/l under a contact time of 15 min. The results indicated that efficiency of UV irradiation improves whenfollowed by chlorination at low concentrations.