EGSB反应器中厌氧颗粒污泥的脱氮特性研究

The characteristics of anaerobic ammonium oxidation by granular sludge from EGSB reactor

以厌氧污泥为接种物,启动膨胀颗粒污泥床(EGSB)反应器,经过3个月的连续运行,反应器中出现了颗粒污泥,表现出持续去除氨氮的能力,并出现了厌氧氨氧化现象.为了验证EGSB反应器中厌氧氨氧化反应的存在,并探讨厌氧颗粒污泥的生物脱氮特性,从EGSB反应器中取出颗粒污泥,并与亚硝化反应器中的活性污泥进行了对比研究.结果表明,好氧污泥反应器对TN、氨氮和亚硝酸盐氮的去除率分别为45 5%、13 4%和99 9%;厌氧颗粒污泥反应器对TN、氨氮和亚硝酸盐氮的去除率分别为54 3%、21 7%和99 9%.厌氧颗粒污泥反应器中NH+4 N的去除速率比较稳定,约为3 17mg·L-1·h-1(以N计).上述结果充分表明,EGSB反应器中发生了厌氧氨氧化反应.

An expanded granular sludge bed (EGSB) reactor was started-up by seeding the anaerobic sludge from brewery wastewater treatment plant. After three months operation, the granular sludge occurred in the reactor, and the ammonium nitrogen could be removed continuously. The morphology and inner structure of the granules was observed using scanning electron microscopy (SEM) and the photographs indicated that the anaerobic granular sludge was relatively regular in shape. The outer layer had a rather fluffy and loose structure and was more transparent compared to the center of the granule. The center of the granule had dense structure. The long-term operational results showed that the maximal removal efficiency of NH^+_4-N was 40% when influent NH^+_4-N concentration was 70～250 (mg·L^(-1)); the NO^-_2-N removal efficiency was more than 98% when influent NO^-_2-N concentration was 70～250 mg·L^(-1); and the COD removal efficiency was 84% at the influent concentration of 500 mg·L^(-1). This revealed that the reaction of anaerobic ammonium oxidation (ANAMMOX) probably taken place in the EGSB reactor. In order to validate the existence of ANAMMOX reaction and investigate the performance of nitrogen removal by anaerobic granular sludge, the granular sludge taken from EGSB reactor and the activated sludge taken from partial-nitrification reactor was used to treat the synthetic wastewater. The experimental results demonstrated that for the activated sludge, the removal efficiency of total nitrogen (TN), NH^+_4-N and NO^-_2-N was 45.5%, 13.4% and 99.9%, respectively; for the anaerobic granular sludge, they were 54.3%, 21.7% and 99.9%, respectively. The removal rate of NH^+_4-N was stable, about 3.17mg·(L·h)^(-1). At the beginning of the reaction, the ANAMMOX process was performed mainly through the pathway of interaction between NH^+_4-N and NO^-_2-N, as time went on, with the exhaustion of NO^-_2-N, the granular sludge could use NO^-_3-N as electron acceptor to oxidize NH^+_4-N, yielding dinitrogen gas. In this research, the COD removal efficiency was about 90.4%. In the light of estimation of COD consumption, the anaerobic granular sludge could use organic carbon source as electron donor, reduce NO^-_2-N and NO^-_3-N, to carry out the traditional denitrification. The results obtained in this study could reveal that in the anaerobic granular sludge reactor the ANAMMOX reaction taken place, accordingly, the existence of anaerobic ammonium oxidation phenomenon in the EGSB reactor could be deduced.