游离氯联合湿干比调控启动CRI系统短程硝化研究

Study on Shortcut Nitrification of CRI System Achieved via Free Chlorine Combined with Wet-dry Ratio Regulation

短程硝化反硝化工艺为解决人工快渗(CRI)系统脱氮效率低的弊端提供了新思路,通过适宜的调控方法启动短程硝化是实现该工艺的关键。为此,考察了游离氯和湿干比对CRI系统内氮素污染物转化的影响,分析了不同阶段的菌群活性和结构特征,探究了游离氯联合湿干比调控启动CRI系统短程硝化的可行性。结果表明,连续添加3 mg/L游离氯23 d后NO2--N积累率稳定在70%左右,亚硝酸氧化菌(NOB)的活性将受到严重抑制且难以在短期内恢复。此时调节湿干比为1∶5,NH4+-N平均去除率、NO2--N平均积累率分别升高至97.41%、94.80%,成功启动短程硝化。16S rRNA高通量测序结果表明,CRI系统内氨氧化菌(AOB)的主要类型为Nitrosomonas、Nitrosovibrio,NOB的主要类型为Nitrospira。CRI系统短程硝化启动成功后,AOB的相对丰度由启动前的4.21%增加到6.69%,而NOB的相对丰度由4.34%降低到0.17%。因此,游离氯联合湿干比调控能选择性抑制NOB活性和促进AOB增殖,可为CRI系统启动短程硝化提供一种可行的新方法。

Shortcut nitrification-denitrification process provides a novel idea to overcome the disadvantage of poor nitrogen removal capacity of constructed rapid infiltration(CRI)systems.The key to realize the process is to start shortcut nitrification through appropriate ways.Therefore,the impacts of free chlorine and wet-dry ratio on the transformation of nitrogen pollutants in CRI system were investigated.The characteristics of bacterial activity and structure in different stages were analyzed.The feasibility of the combination of free chlorine and wet-dry ratio regulation to start shortcut nitrification in CRI system was explored.The results showed that NO2--N accumulation rates were stable at around 70%after adding 3 mg/L free chlorine for 23 days,and the activity of nitrite oxidation bacteria(NOB)would be severely inhibited and could not be recovered in a short time.At this time,the average removal rates of NH4+-N and accumulation rates of NO2--N were increased to 97.41%and 94.80%respectively when adjusting the wet-dry ratio to 1∶5,and shortcut nitrification was started successfully.High throughput sequencing of 16 S rRNA showed that the main types of ammonia oxidation bacteria(AOB)were Nitrosomonas and Nitrosovibrio,and the main type of NOB was Nitrospira.The relative abundance of AOB increased from 4.21%to 6.69%,while that of NOB decreased from 4.34%to 0.17%.Therefore,the NOB activity could be selectively inhibited and the proliferation of AOB be promoted via the combination regulation of free chlorine and wet-dry ratio,which provided a novel method for the achievement of shortcut nitrification in CRI system.