基于分点进水的垃圾渗滤液短程硝化反硝化脱氮性能

Nitrogen removal performance of short-cut nitrification and denitrification process based on step feeding strategy for landfill leachate treatment

在垃圾渗滤液短程硝化反硝化生物脱氮过程中,过高浓度的游离氨(FA)会抑制氨氧化菌(AOB)的活性,降低系统亚硝化速率和脱氮效率。采取分点进水的方法,合理分配进入系统各单元的基质,降低反应器营养负荷和FA浓度,以期减少FA对AOB的抑制,提高脱氮效率。结果表明,通过控制DO浓度小于1.0 mg·L^(-1),成功实现了稳定的短程硝化反硝化;当水力停留时间(HRT)为6.25 d时,亚硝态氮累积率(NAR)可达到84.97%;当缩短HRT至5.5 d时,氨氮去除率降低到69.63%左右,总氮去除率(NRE)仅有18.06%。对系统内的FA分析发现,O1、O2池中FA浓度达到了36.32 mg·L^(-1)以上,均超过了AOB抑制浓度限值,因而限制了亚硝化过程。采用分点进水方式运行后,HRT为5.5 d时,氨氮去除率仍有89.86%,NRE为27.62%,NRE相比分点进水前提高了52.93%;当HRT缩短到5.0 d时,氨氮去除率仍然高于81.25%。分点进水条件下O1、O2池中FA浓度分别降低到7.91 mg·L^(-1)和5.81 mg·L^(-1),此时,FA既能有效抑制NOB,又不会对AOB产生严重抑制。以C/N=4向脱氮系统补充碳源后,系统NRE迅速提升到80%左右。微生物测序结果表明,分点进水后O1、O2、O3、O4池中AOB菌属相对丰度为2.27%、1.77%、2.75%、1.37%,相比于分点进水前分别提升了12.37%、68.57%、57.14%、59.30%。这表明分点进水有利于提高AOB的生长优势和短程硝化过程。以上结果表明,对于垃圾渗滤液的处理,分点进水运行方式可以有效提高短程硝化和脱氮效率,具有很好的工程应用价值。

During biological nitrogen removal process treating landfill leachate by using short-cut nitrification and denitrification technology,high concentration of free ammonia(FA)can inhibit the activity of ammonia oxidizing bacteria(AOB),reduce the nitrosation rate and nitrogen removal efficiency.In this study,step feeding strategy was used to reduce the inhibition of FA on AOB and thereby improve the nitrogen removal efficiency because of the rational distribution of the substrates and decrease of the substrate/microorganism ratio and FA content.The result showed that the stable short-cut nitrification and denitrification was successfully realized through controlling the DO concentration below 1.0 mg·L^(-1),and the nitrite accumulation rate(NAR)reached84.97%at the hydraulic retention time(HRT)of 6.25 d.When HRT was shortened to 5.5 d,the N H4+-N removal rate decreased to about 69.63%,and nitrogen removal efficiency(NRE)was 18.06%.It found that FA concentrations in the O1 and O2 tanks were higher than 36.32 mg·L^(-1),which exceeded the AOB inhibitory concentration limit,and the short-cut nitrification process was inhibited.After step feeding mode was used,NH4+-N removal rate was 89.86%at HRT of 5.5 d,and NRE was 27.62%which was 52.93%higher than that before step feeding.When HRT was shortened to 5.0 d,the NH4+-N removal rate was still higher than 81.25%.FA concentrations in O1 and O2 tanks decreased to 7.91 mg·L^(-1) and 5.81 mg·L^(-1),respectively in the step feeding process.Under this condition,FA could effectively inhibit NOB while didn’t severely inhibit AOB.After supplementing the carbon source according to C/N=4,the NRE of the system reached about 80%.The microbial sequencing results showed that the relative abundances of AOB in O1,O2,O3 and O4 tanks were2.27%,1.77%,2.75%and 1.37%,respectively,which increased by 12.37%,68.57%,57.14%and 59.30%compared with the process without step feeding mode.This further indicated that the step feeding process was beneficial for the growth of AOB and short-cut nitrification process.The above results showed that for the treatment of landfill leachate,the step feeding strategy can effectively improve the short-cut nitrification and nitrogen removal efficiency,and it’s valuable for practical application.