基于群体感应与群体淬灭的自养脱氮工艺稳定运行调控机制研究

Autotrophic nitrogen removal process was an important part of sustainable wastewater treatment systems. But because of the low growth rate of autotrophic nitrogen removal bacteria, lead to the long startup time of process, and the recovery of sludge concentration was slow when it had lost in operation. At the same time, the growth of the nitrite oxidizing bacteria made the accumulation of nitrate nitrogen in effluent. And conventional measures cannot solve the problem very well which affected stable operation of process. Quorum sensing was a common communication mechanism exists between bacteria. Quorum sensing could regulate the gene expression to control the bacteria community behavior according to the population density. This project will adopt ultra-performance liquid chromatography tandem mass spectrometry to detect the quorum sensing signal molecules of autotrophic nitrogen removal reactor under different running condition. It could screen out the advantage signal molecules of aerobic ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria, nitrite oxidizing bacteria and the signal molecules between bacterial species. And then by adding corresponding signal molecules to strengthen the advantages of quorum sensing, which could speed up the growth of aerobic ammonia oxidizing bacteria and anaerobic ammonia oxidizing bacteria. Through the addition of quorum quenching enzymes to inhibit the growth of nitrite oxidizing bacteria. Also using high-throughput pyrosequencing and fluorescence quantitative PCR technology to analysis the regularity of population dynamics under different conditions. Then this study will clarify the regulatory mechanism of quorum sensing and quorum quenching, and propose the control strategies of stable operation for autotrophic nitrogen removal process.

自养脱氮工艺是可持续污水处理系统中的重要组成部分。但因为自养脱氮功能菌的生长速率较慢，导致工艺启动时间长，且运行中污泥流失后恢复慢；同时亚硝酸盐氧化菌的生长使得出水中硝酸盐氮积累。而常规的调控措施未能很好地解决这些影响工艺稳定运行的问题。群体感应是一种普遍存在于细菌之间的通讯机制，它具有根据种群密度调控基因表达，控制细菌群体行为的功能。本项目将采用超高效液相色谱串联质谱法检测自养脱氮反应器不同运行状态下的群体感应信号分子，分别筛选出好氧氨氧化菌、厌氧氨氧化菌和亚硝酸盐氧化菌的优势信号分子以及系统中的种间信号分子。而后通过外加相应的优势信号分子强化群体感应加快好氧氨氧化菌和厌氧氨氧化菌的生长，同时通过外加群体淬灭酶抑制亚硝化盐氧化菌的生长。采用高通量测序和荧光定量PCR等技术，分析相应条件下微生物种群变化规律，明晰群体感应和群体淬灭的调控机制，提出维持自养脱氮工艺稳定运行的控制策略。

在自养脱氮工艺的实际工程中，主要存在如下问题：好氧氨氧化菌和厌氧氨氧化菌的生长速率较慢，使得启动时间较长，污泥流失后难以及时补充；短程硝化控制失当，使得亚硝酸盐氧化菌大量生长，出水硝酸盐氮积累。这些问题都严重影响自养脱氮工艺的高效稳定运行和广泛应用。群体感应是一种普遍存在于细菌细胞之间的通讯机制，它具有根据种群密度和周围环境变化调控基因表达，控制细菌群体行为的功能。而群体淬灭则是通过减弱或者干扰细菌的群体感应，阻止相应性状的表达，抑制相应微生物种群增长。这也为解决以上两个问题提供了新的思路，即通过强化群体感应或群感淬灭以加快好氧氨氧化菌和厌氧氨氧化菌的生长，抑制亚硝化盐氧化菌的生长。. 本项目以明晰群体感应及群体淬灭对自养脱氮的影响为目标，主要分为以下三部分研究内容：常规调控参数对自养脱氮的影响；群感淬灭对自养脱氮的影响；自养脱氮工艺优势群体信号分子的筛选。通过研究取得了如下成果：综述了群体感应在自养脱氮中的应用进展；成功启动和长期运行了短程硝化反应器，并明晰其微生物特征；明晰了不同类型不同水质自养脱氮反应器的微生物特征；明晰了不同氨氮浓度不同粒径厌氧氨氧化颗粒污泥的脱氮性能及微生物特征；明晰群感淬灭对自养脱氮的影响；明晰自养脱氮工艺优势群体信号分子。其中添加广谱性淬灭酶后，短程硝化反应器的氨氮氧化率和亚硝化率都有下降。此外，过量淬灭酶的加入会改变厌氧氨氧化反应器的脱氮路径。因此，采用群感淬灭时，需要谨慎考虑污泥中各类微生物的数量占比。研究中初步确定了短程硝化的优势信号分子为C6-HSL，而厌氧氨氧化的优势信号分子为C14-HSL。以上这些成果可凝练出基于群体感应的自养脱氮调控机制，为自养脱氮工艺的长期稳定运行提供技术指导。