固体碳源反硝化滤池脱氮效果及沿程生化特性

在污水处理工艺末端嵌入固体碳源反硝化滤池，可以不改变污水处理厂的原有工艺提高总氮去除效率，方便应对污水厂的提标压力和低碳源污水的脱氮问题。针对生化池尾水硝酸盐特性，以聚己内酯（PCL）作为填充床构建了固体碳源反硝化生物滤池，研究了该反应器的脱氮性能以及生物滤池的沿程生物量和微生物群落结构。结果表明，TN为32.0~37.7 mg·L-1、硝态氮为30.2~34.9 mg·L-1的生化池尾水进入该固体碳源反硝化池后，在HRT为1.5 h的情况下，出水TN在1.1~3.5 mg·L-1之间，硝态氮低于1 mg·L-1，平均去除率均大于94%。研究发现，固体碳源反硝化滤池对硝态氮的转化去除主要发生在40 cm填料以下；生物量的大小也随滤层高度的增加逐渐降低，且与滤层高度呈良好的线性负相关关系（y=-0.471x+38.77，R2=0.976）。采用PCR-DGGE技术研究了固体碳源反硝化滤池的沿程微生物群落结构特征，发现滤层底部（进水端）尽管生物量多，但微生物多样性低，滤池的中部是生物多样性最丰富的区域，香农威尔指数分别为1.95和2.40。DGGE图谱特征条带的16S rDNA序列分析表明生物膜中微生物变形菌门（Proteobacteria）占优势，主要微生物包括能降解PCL的细菌Comamonas，以及常见的反硝化细菌Dechloromonas、Rubrivivax和发酵产乙酸的硫酸盐还原菌Desulfobacter，从微生物群落关系结构角度支撑了固体碳源反硝化过程的顺利进行。

Denitrification performance of solid-phase denitrification biofilter and biochemical characteristics along its height

Embedding a solid-phase denitrification biofilter at the end of the wastewater treatment process could improve the total nitrogen removal efficiency without changing the original process of the sewage treatment plant and provide a means to deal conveniently with the pressure to reconstruct wastewater treatment plants to address the stricter criterion as well as the nitrogen removal of low carbon source wastewater. In this research,polycaprolactone (PCL) granules were used as both a carbon source and biofilm carrier for nitrate removal from the municipal sewage biochemical effluent. The nitrogen removal efficiency of the reactor and changes in biochemical characteristics along the filter,such as biomass and microbial community structure,were studied. The results showed that the effluent TN was from 1.1 to 3.5 mg·L-1,the nitrate concentration was below 1 mg·L-1,the average removal rate of nitrate was more than 94% when the influent TN was from 32.0 to 37.7 mg·L-1,and the nitrate concentration was from 30.2 to 34.9 mg·L-1 at a hydraulic retention time of 1.5 h. The removal of nitrate occurred mainly at a height lower than 40 cm in the filter. The biomass decreased gradually with an increase in filter height and had a negative linear correlation with the filter height (y=-0.471x+38.77,R2=0.976). Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)was used to investigate the dynamic change in the microbial community of the biofilm attached to the PCL granules along the filter. The results showed that the Shannon-Wiener index of microbial diversity was lowest at the bottom of the filter (1.95)and most abundant in the middle of the filter (2.40). According to the 16S rDNA sequences of the PCR-DGGE profile,the bacteria in highest abundance in the solid-phase denitrification biofilm was Proteobacteria. Comamonas,Dechloromonas,and Rubrivivax were the predominant denitrifying bacteria in the solid-phase denitrification biofilter,where Comamonas could degrade the solid carbon substrate to obtain the necessary electron donor for denitrification. Moreover,sulfate-reducing bacteria,which can produce acetic acid by fermentation,were observed in the biofilm. The abundant microbial community structure could support successful denitrification using a solid carbon source.