臭氧、一氯胺顺序消毒过程中pH作用研究

THE FUNCTION OF PH IN SEQUENTIAL USE OZONE AND MONOCHLORAMINE TO DISINFECTION

以单宁酸替代饮用水中的天然有机物,对臭氧、氯胺顺序消毒过程中臭氧和氯胺的衰减以及消毒副产物生成与pH之间的关系进行了研究。结果表明,臭氧消毒阶段臭氧投加量由0.5 mg·L-1增加到5 mg·L-1,24 h后溶液的pH从5.9下降到4.3;相应地,随着臭氧投加量的逐渐增加,氯胺消毒阶段一氯胺的衰减速率逐渐变慢,减少了氧化天然有机物所消耗的一氯胺。在pH为8.3,一氯胺的稳定性最好,但与pH对消毒效果的影响不一致,将pH控制在7.0左右可能更理想;二氯乙酸在pH为6.8时生成最多,三氯甲烷和三氯乙酸也基本在pH为7.0～7.5时达到最大。臭氧氯胺顺序消毒过程中,pH对一氯胺的衰减和消毒副产物生成的影响较大,应加强控制。

Tannic acid was used as surroguate of natural organic matter （NOM）. A study was conducted to evaluate the relationship of disinfectants decay and disinfection byproducts formation with pH variation. The results showed that, during the ozonation, with the ozone dosage increased from 0.5 mg· L^-1 to 5 mg · L^-1, the pH of samples decreased from 5.9 to 4.3; correspondingly, with the increase of ozone dosage, the monochloramine decayed more slowly and the monochloramine loss for NOM oxidation was also decreased. At pH 8.3, monochloramine was the most stable, but not consistent with the effect of disinfection. Therefore, pH 7.0 maybe an ideal condition. DCAA（dichloroacetic acid） yield arrived the peak at pH 6.8, and the yields of TCM （trichloromethan） and TCAA （triehloroaeetic acid） also arrived the peak at the range of pH 7.0 and pH 7.5. When ozone and monochloramine were sequential used to disinfection, the monochloramine decay and DBPs （Disinfection Byproducts） formation were impacted strongly by pH, which should be well controlled.