底物流加-间歇运行方式下氨氧化细菌富集培养的效果及影响因素分析

Analysis on the effect of ammonia-oxidizing bacteria enrichment and its influence factors under the substrate continuous feeding in a sequencing batch reactor

富集培养氨氧化细菌(AOB)可为污水处理工艺提高氨氮氧化速率、促进亚硝酸盐积累提供物质基础。在(20±2)℃下,采用底物流加-间歇运行方式进行氨氧化细菌富集培养,重点考察了游离氨(FA)、游离亚硝酸(FNA)、溶解氧(DO)等因素的影响,并对富集前后活性污泥样品中的AOB进行了定性定量分析。结果表明:第15天左右AOB增殖进入稳定生长期,比氨氮氧化速率由接种时的4.45 mg·(g·h)-1升高至57.22 mg·(g·h)-1;通过pH、底物流加速率和实际反应速率关系的联合控制,可以实现整个反应过程中FA和FNA在预期范围内波动;即使在极低的DO条件下,高纯度的AOB也可进行氨氮氧化。高通量测序结果表明,体系内Nitrosomonas属的AOB大幅度增长,可由0.23%上升至54.18%,亚硝酸盐氧化细菌(NOB)的生长得到了有效抑制,培养结束时仅为0.12%。荧光定量PCR对AOB功能基因amoA的绝对含量结果表明,富集前后平均拷贝数由2.67×105 copies·g-1升至最大,可达9.67×109 copies·g-1,AOB成为活性污泥中的优势菌。本研究结果可为常温条件下快速富集AOB提供参考。

The enriched ammonia-oxidizing bacteria(AOB) was added into wastewater treatment systems,which could provide the foundation for promoting the ammonia oxidation and nitrite accumulation. AOB was enriched in a sequencing batch reactor(SBR) with continuous feeding of ammonia at the temperature of(20±2)℃, and the effects of free ammonia(FA), free nitrous acid(FNA) and dissolved oxygen(DO) were evaluated,and the identification and quantification analysis of AOB was also performed in the sludge samples before and after the enrichment. The results indicated that the AOB reached the growth stability period around day 15, and the specific ammonia oxidation rate increased from 4.45 mg·(g·h)-1 at inoculation stage to a maximum level of 57.22 mg·(g·h)-1. The expected FA and FNA concentrations could be controlled systematically with the regulation on pH and the relationship between the substrate continuous feeding rate and the real reaction rate.Even at very low DO conditions, ammonia could be oxidized by AOB with high ratio. High-throughput sequencing demonstrated that AOB affiliated to Nitrosomonas was highly enriched, and increased from 0.23% to 54.18%. The nitrite-oxidizing bacteria(NOB) growth was inhibited, and only remained 0.12% at the end of cultivation. The copy number of gene amoA for AOB increased from 2.67×105 copies·g-1 to a maximum value of 9.67×109 copies·g-1 during the enrichment period by quantitative real-time fluorescence polymerase chain reaction(qPCR), and AOB became the predominated bacteria in the cultivated sludge. This work can guide rapid enrichment of AOB at normal temperature.