Influencing pathways and toxicity changes of pre-ozonation on carcinogenic NDEA formation from greenhouse gas adsorbent DEAPA in subsequent disinfection processes

This study was to evaluate the feasibility of controlling carcinogenic nitrosodiethylamine (NDEA) formation from greenhouse gas adsorbent 3-diethylaminopropylamine (DEAPA) by pre-O3 in subsequent chlorination/chloramination processes. The result indicated that the NDEA yields (0.4 %) during chlorination was 1.3 times of that during chloramination (0.3 %); pre-oxidation with 4 mg/L O3 significantly cut down its formation; the reduction rates were up to 67.5 and 48.5 %, respectively. OH scavenger greatly augmented the final NDEA amount from 1.86 to 5.05 mu g/L during ozonation, while its roles on subsequent processes differed with disinfection methods as well as O3 (g) dosages. Most of co-existed substances inhibited NDEA generation, except NO2-, CO32- and SO42-, which slightly promoted during ozonation. Basing on Gaussian calculation, GC/MS and UPLC-Q-TOF-MS analysis, the influencing mechanisms of pre-O3 on NDEA formation in subsequent disinfection processes were proposed. In addition, the calcu-lated toxicity analysis as well as the whole toxicity was applied to evaluate the possibility of pre-O3 on risk control.

Automated summary

This study evaluated the feasibility of using 3-diethylaminopropylamine (DEAPA) as a greenhouse gas adsorbent to control the formation of carcinogenic nitrosodiethylamine (NDEA) in chlorination/chloramination processes. The results showed that the pre-oxidation with 4 mg/L O3 significantly reduced NDEA formation, with reduction rates of 67.5% and 48.5% in chlorination and chloramination, respectively. The presence of an OH scavenger increased the final NDEA concentration during ozonation. The study also proposed the mechanisms through which pre-O3 influenced NDEA formation in subsequent disinfection processes.