FORMATION OF TRICHLORONITROMETHANE FROM ASPARTIC ACID DURING UV/CHLORINE DISINFECTION

The formation of trichloronitromethane (TCNM) was investigated during the chlorination of aspartic acid under low pressure (LP) UV irradiation (lambda=254nm). LP UV/chlorine disinfection enhanced the formation of TCNM for the first instance, furthermore the concentration of TCNM increased by 10 times in 5 mins. Then, an obvious decrease was observed in the formation of TCNM, and TCNM was nearly undetectable after 22 min. The effects of light intensity, initial concentration of aspartic acid, pH value, free chlorine concentration and the addition of tertbutanol (TBA) on the formation of TCNM were also investigated under UV/chlorine condition. The formation of TCNM increases with the increase of pH value, UV light intensity, initial concentration of aspartic acid, free chlorine concentration. TBA has a minor effect on formation of TCNM in the solution containing aspartic acid under UV/chlorine condition. So hydroxyl radical doesn't play a most important role in TCNM formation from aspartic acid under UV/chlorine. A possible integrated pathway of TCNM formation from aspartic acid is proposed under UV/chlorine. The new information obtained in this study will reduce the risk of TCNM formation during the treatment of drinking water and waste water. It will helpful for the control of TCNM formation in drinking water and sewage treatment and the development of new disinfection process.