城市污水生物脱氮系统出水经氯胺消毒形成NDMA的影响因素研究

为了考察城市污水回用时氯消毒过程中NDMA的形成,以2套生物脱氮实验装置厌氧/缺氧/好氧(A/A/O)和缺氧/好氧(A/O)的二沉池出水为对象,研究了氯胺消毒过程中氯胺剂量、pH、NO2--N和NO3--N浓度对N-亚硝基二甲胺(NDMA)形成的影响.结果表明,二沉池出水中仍然含有微量的NDMA前体物,导致了氯胺消毒过程中NDMA的形成,而且NDMA的浓度会随氯胺浓度的增加呈线性增加;在中性或稍偏碱性(pH 7～8)的条件下,NDMA生成量最大;二沉池出水中NO2--N和NO3--N的浓度对NDMA的含量皆不会产生明显影响.

Factors Influencing the Formation of NDMA During Chloramination Disinfection of Effluent from Biological Nitrogen Removal System for the Treatment of Municipal Sewage

In order to investigate the formation of N-nitrosodimethylamine (NDMA) during the chloramination disinfection process for the recycling of municipal sewage, the effluents from two lab-scale biological nitrogen removal systems anoxic/oxic (A/O) and anaerobic/anoxic/oxic (A/A/O) processes were disinfected using chloramine. The effects of chloramine dosage, pH, the concentration of NO₂^--N and NO₃^--N on the formation of NDMA were investigated. The results showed that there were trace NDMA precursors existing in the effluents, resulting in the formation of NDMA during chloramination disinfection process; the concentration of NDMA increased linearly with the increase of chloramine dosage. Neutral or light alkaline conditions (pH 7-8) were beneficial to NDMA formation. NO₂^--N and NO₃^--N had no significant effects on the formation of NDMA in the process of chloramination.