稀土Er(Ⅲ)对短程硝化性能的影响及其抑制动力学特性

Influence of rare earth element Er(Ⅲ) on performance of short-cut nitrification and its inhibition kinetics

研究了重稀土元素铒[Er(Ⅲ)]对短程硝化工艺的短期和长期脱氮效能影响,并进行了相关动力学分析。短期实验表明,0~10mg/L的Er(Ⅲ)对AOB菌活性呈现促进作用,20~60mg/L的Er(Ⅲ)对AOB菌活性呈现轻度抑制,80~120mg/L的Er(Ⅲ)则对AOB菌活性呈现重度抑制。AOB菌会吸附大量Er(Ⅲ),在进水Er(Ⅲ)浓度低于60mg/L时,Er(Ⅲ)去除率均大于90%,高于60mg/L后Er(Ⅲ)去除率逐渐降低。ICP-MS和EDS分析结果表明,Er(Ⅲ)可被AOB菌胞外吸附和胞内摄取,其中又以胞外吸附为主。分别采用Vadivelu模型、Hellinga模型、Michaelis-Menten模型和Hill模型对实验结果进行拟合,结果表明通过分段拟合(0~60mg/L和60~120mg/L) Hill模型能较好的描述Er(Ⅲ)对AOB菌的抑制动力学过程,拟合得到的R2分别为0.9879和0.9999,最大基质去除速率qmax(ΔSNPR)分别为2.59mg/(g·h)和7.15mg/(g·h)。长期试验表明,10mg/L的Er(Ⅲ)将使短程硝化系统性能逐渐消失,停止添加Er(Ⅲ)后,反应系统性能也不能恢复。

The effect of the heavy rare earth element erbium [Er(Ⅲ)] on the short-term and long-term nitrogen removal efficiency of the short-cut nitrification process was studied,and the related kinetic analysis was carried out.Short-term experiments showed that Er(Ⅲ) at the concentration of 0—10mg/L promoted the activity of AOB bacteria,20—60mg/L Er(Ⅲ) slightly inhibited the activity of AOB bacteria,and 80—120mg/L Er(Ⅲ) showed severe inhibition on the activity of AOB bacteria.AOB bacteria would adsorb a large amount of Er(Ⅲ),and the Er(Ⅲ) removal rate was greater than 90% when the influent Er(Ⅲ) concentration was lower than 60mg/L.However,the Er(Ⅲ) removal rate gradually decreased when the influent Er(Ⅲ) concentration was higher than 60mg/L.The results of ICP-MS and EDS analysis showed that Er(Ⅲ) could be adsorbed extracellularly and uptaked intracellularly by AOB bacteria,and the extracellular adsorption was the main one.The experimental results were fitted by Vadivelu model,Hellinga model,Michaelis-Menten model and Hill model,respectively.The results showed that the inhibition kinetics process of Er(Ⅲ) on AOB bacteria can be better described by subsection fitting(0—60mg/L and 60—120mg/L) using Hill model,the R2 obtained by fitting are 0.9909 and 0.9999,respectively,and the maximum matrix removal rate qmax(ΔSNPR) was 2.59mg/(g·h) and 7.15mg/(g·h),respectively.Long-term experiments showed that the performance of the short-cut nitrification system will gradually disappear with the addition of 10mg/L Er(Ⅲ),and the performance of the reaction system could not recover after the addition of Er(Ⅲ) was stopped.