Removal Of Odorants And Microcystin-LR In Water By Ultraviolet Combined With Chlorine

The influence of odor on water can be extended to the environmental pollution of water bodies and the safety of drinking of residents.In recent years,drinking water accidents caused by algae caused by algae are common.The conventional water treatment techniques are not efficiency for removing these odorants.In this paper,2-methylisoborneol(2-MIB)and geosmin(GSM)were used as representatives of algae odorants to study the removal efficiency by the combination use of ultraviolet and chlorine(UV/Cl).The results indicated that synergistic effect of UV/Cl can significantly enhance the degradation of 2-MIB and GSM,which can be completely removed in 30 min.The degradation kinetics constants under UV/Cl treatment increased with increasing chlorine dosage.The degradation efficiency cannot be affected at acid condition,but decreased with increasing pH value when pH > 7.UV/Cl showed good degradation efficiency on 2-MIB and GSM in real water,but the kinetic constants of in real water are obviously lower than those in pure water system.Beyond odorants,the algae can also release microcystins like microcystin-LR(MC-LR),a toxin which is very toxic and poses a threat to public health when entering water treatment works.conventional water treatment processes,including coagulation,flocculation and filtration,are not effective for MC-LR removal.The MC-LR degradation during UV/chlorine treatment was examined and results shows: 26.6% of the MC-LR can be removed in 30 min by UV irradiation,78.1% of the MC-LR can be removed by chlorination 30 min and MC-LC can be completely removed in 10 min by combination use of UV and chlorine.Chlorine dosage has significant influence on MC-LR removal by UV/Cl process,10 min is needed to achieve completely remove for 5 mg/L chlorine but 30 min is needed for 1 mg/L chlorine.The degradation efficiency cannot be affected at acid condition,but decreased with increasing pH value when pH > 7.The bulk quality has significant influence on MC-LR removal by UV/Cl process,56.7% of MC-LR can be removed in 10 min for sand filtrated water,whereas 46.9% for influent of drinking water treatment plant.The formation of disinfection byproducts during UV/Cl process is much lower than chlorination.However,contrary results was obtained for disinfection byproducts formation potential.