Methods of Controlling THMs and HAAs Formation during Reclaimed Water Chlorination

Abstract

Trihalomethanes (THMs) and haloacetic acids (HAAs) formation character of two samples collected from a reclaimed water treatment plant (RWTP) in North China was investigated, and the chlorination was found brought a high THMs (0.30~0.36μmol/mmol-DOC) and HAAs (2.38~3.07μmol/mmol-DOC) yields in the samples. In order to control THMs and HAAs formation during reclaimed water chlorination, the impact of ammonia addition (to NH3-N=8.3, 17, 24, 30mg/L), pH adjusting (to pH=4.4, 5.04, 7.93, 8.7) and ozone oxidation (with 5.1, 9.3, 13.6, 17.4mg-O3/L) before sample chlorination were tested respectively and compared with each other. Finally, ammonia addition (to NH3-N=17mg/L) was proven with greatest efficacy on DBP formation and bromide incorporation control (TTHM, THAA, THM bromide incorporation and HAA bromide incorporation were reduced by 15.41%, 28.21%, 26.88% and 13.63% respectively).