共基质模式下铁盐脱氮反应器的运行性能及微生物学特征

铁盐作为自养反硝化电子供体时,被氧化产生的高价铁易于沉淀,使得反硝化微生物表面产生"铁壳",其抑制微生物的活性,甚至导致微生物死亡.为解决自养铁盐脱氮反应器因"铁壳"包被而导致的反应器效能下降问题,本文采用共基质模式培养铁盐脱氮反应器,即在反应器进水中适量添加少量乙酸钠,作为有机电子供体,以期实现铁盐脱氮反应器的高效、稳定运行.结果表明,添加适量有机物可使得铁盐脱氮反应器高效稳定运行,效能(以N计)达0. 51 kg·(m3·d)-1,稳定运行约30d.共基质模式下,反应器运行期间始终可以检测到异养菌.结合污泥的TEM检测结果,发现在铁盐脱氮反应器稳定运行期间,异养菌是铁盐脱氮主力军,其独特的铁盐代谢方式可有效避免铁壳形成.本项研究有效解决了铁盐脱氮过程中微生物"铁壳"包被难题,将助力于自养脱氮技术的研发及应用.

Operational Performance and Microbiological Characteristics of an Iron-Salt Denitrification Reactor in Co-substrate Mode

When iron salt is used as an autotrophic denitrification electron donor, the high iron yield generated by oxidation is easy to precipitate, resulting in "iron encrustation" on the surface of denitrifying microorganisms, which inhibits their activity and even leads to their death. In order to solve the degradation of the efficiency of the autotrophic ferric denitrification reactor caused by the "iron encrustation" coating, this paper adopted the co-substrate mode to cultivate the ferric denitrification reactor; that is, a small amount of sodium acetate was added into the water of the reactor as an organic electron donor, to realize the efficient and stable operation of the ferric denitrification reactor. The results showed that adding an appropriate amount of organic matter could make the iron salt denitrification reactor run efficiently and stably, with an efficiency of up to 0.51 kg·(m³·d)^-1, for more than 30 days. Heterotrophic bacteria could always be detected during the operation of the reactor in the co-substrate mode. Combined with the transmission electron microscopy (TEM) test results of the sludge, it was found that during the stable operation of the iron-salt denitrification reactor, heterotrophic bacteria were the main cause of iron-salt denitrification, and their unique iron-salt metabolism mode could effectively avoid the formation of iron encrustation. This study effectively solved the problem of microbial "iron encrustation" coating in the process of iron-salt denitrification, and will contribute to the development and application of autotrophic denitrification technology.