污泥反硝化除磷-诱导磷结晶工艺中硝化池内的微生物特性

摘要

Nitrogen and phosphorus are known as two main factors contributing to eutrophication of water body. A novel two-sludge denitrifying phosphorus removal and phosphorus recovery process responsible for simultaneous nitrogen and phosphorus removal from wastewater was established in our previous studies. Many reports suggested that a better understanding of microbial communities in a wastewater treatment process could give an important guidance for stable operation as well as reconstruction. In addition, nitrification is the limiting procedure based on the theory of simultaneous nitrogen and phosphorus removal. For this, this paper analyzed the microbial characteristics in nitrification pond within a two-sludge denitrifying phosphorus removal and phosphorus recovery process by using fluorescence in situ hybridization (FISH), scanning electron micrograph (SEM) and the software of Image-Pro Plus (IPP). In this process, the abundance of ammonia-oxidizing bacteria (AOB) responsible for the transformation of ammonia nitrogen to nitrite was significantly higher than that of nitrite-oxidizing bacteria (NOB) capable of the conversion of nitrite to nitrate. According to the FISH analysis, the proportion of AOB to total bacteria was 46.2%, while NOB was 28.5%. Generally, the AOB was close to the external layer of sludge granule while the NOB was in the internal layer. From SEM, the nitrifiers in the nitrification pond were typically coccus or short rods and preferably grown the dense clusters. The aggregates formed by the AOB were bigger than those of NOB tending to combine with several cells. Based on the three dimensional graphs of microstructures of nitrification sludge analyzed by using IPP software, it was found that the structure was density in the external layer, while that was loose in the internal layer and much void or hollows were found as well, which might be due to the difference of the abundance of microorganisms and the concentrations of nutrients and oxygen between the external and the internal. In conclusion, compared with the conventional single-sludge wastewater treatment processes, two-sludge denitrifying phosphorus removal processes have a great advantage to enrich the nitrifiers. Therefore, these results obtained here could be effective for optimization of process parameters or construction of pilot plant and design of wastewater treatment process responsible for nitrogen and phosphorus removal as well.%　　为了探究双污泥系统下反硝化除磷-诱导磷结晶工艺中硝化池内微生物特性,该文利用原位荧光杂交(fluorescence in situ hybridization,FISH)技术、电子显微镜扫描(scanning electron micrograph,SEM)方法和Image-Pro Plus(IPP)软件考察了该工艺中硝化细菌的种群结构、形态和硝化污泥微观三维结构图.结果表明：该工艺中硝化池内氨氧化细菌(ammonia-oxidizing bacteria,AOB)数量要多于亚硝酸盐氧化细菌(nitrite-oxidizing bacteria,NOB),占总细菌的比例分别为46.2%,28.5%,且AOB处于污泥颗粒外层而NOB处于污泥颗粒内层,可能由于NOB利用AOB的代谢产物所致；工艺中硝化细菌多以球形或短杆菌为主,NOB生长时多以几个细胞形成小团聚体,而 AOB 生长时则形成大的团聚体；通过硝化污泥微观三维结构发现,污泥外层呈密实状而内层较疏松且有空洞存在,可能由于污泥外层和内层微生物的丰度差异、营养物质和溶解氧的浓度差异所致.此外,与传统的单污泥污水处理工艺相比,双污泥工艺明显地增强了硝化细菌的生长和富集能力.