生物脱氮除磷系统中微丝菌代谢分子影像过程及污泥膨胀控制机制

Nowadays, sludge bulking caused by Microthrix parvicella has been the hot research point in environmental field. Plenty of research has been focused on the reason of the overgrowth of M. parvicella as well as its growth metabolism mechanism. However researchers havn’t found an efficient method to inhibit the bulking until now. In our study, we intend to design and synthesize molecular imaging probes, which can specifically target to M. parvicella and other markers in the bacteria. By observing the absorbtion, transfer and catabolism process of long chain fatty acids (LCFAs) in the presence of M. parvicella in sludge, we will investigate the amount change, velocity and spatial distribution regularities of the polyphosphate and polymer in cells. A mathematical model will be built based on the relationship between the fluorescence information and the metabolism of M. parvicella, enengy, sludge bulking, etc. Furthermore, we will explore the the relationship between the metabolism of M. parvicella and sludge bulking, deeply understand the key factor of sludge bulking caused by M. parvicella, and study the control condition to inhibit the bulking. By adding LCFAs modified micro silica fume into the sludge system, finally we will investigate the aggregation morphology of M. parvicella and the effect of silica fume on sludge settleability. The scientific significance of the study is to reveal how the metabolism of M. parvicella can determine the sludge bulking, which is of great importance to inhibit and control the sludge bulking.

微丝菌导致的污泥丝状膨胀是国内外该领域关注的热点问题，对其生长代谢机制与微丝菌过度繁殖关系方面已有很多研究报道,但到目前为止还没能找到及时抑制其膨胀的有效方法。本项目采用设计制备的微丝菌及体内标记物的靶向分子影像探针，观察微丝菌在污泥原位条件下对长链脂肪酸（LCFAs）的吸收、运移、分解代谢过程，探索微丝菌代谢过程中胞内聚合物、聚磷盐的数量变化、赋存速率和空间分布规律，研究其定性定量荧光信息与微丝菌的代谢作用机制、能量关系及污泥膨胀的相关性并建立数学模型；探索微丝菌生命代谢特征与污泥膨胀过程的相关性,加深对微丝菌导致污泥膨胀关键因素的理解，探求微丝菌导致污泥膨胀的抑制和控制因素。投加LCFAs表面修饰的微硅粉，研究污泥系统中微丝菌的聚集形态及对污泥沉降性能的影响。其科学意义在于揭示微丝菌在污泥系统中的代谢过程对污泥膨胀状态的决定关系，这对抑制和控制微丝菌污泥膨胀具有重要意义。

设计合成了咔唑-吡啶类、咔唑-喹啉类荧光探针分子，并采用不同碳链长度的烷烃和脂肪酸对其进行修饰。18碳酸及是18碳烷烃修饰的探针分子对活性污泥中微丝菌具有较好的识别特性。构建了荧光信号与活性污泥中的微丝菌的定量关系，进一步优化了荧光传感对微丝菌的定量方法。制备了无机量子点探针，采用LCFA对其进行修饰，可实现定向标记活性污泥中微丝菌，荧光特性优异。采用无机量子点与有机染料进行复合，构建了具有FRET光学特性的复合探针，可对污泥中微丝菌等丝状菌识别和定量判断进行了初步研究。利用染料和不同尺寸的量子点探针分别原位标记微丝菌，探索了菌胶团的孔径尺寸的评价方法，发现分子探针可以无阻碍进入到菌胶团内部，而量子点探针根据探针粒径的不同，可以分别进入到孔洞或受阻，粒径小的探针能够进入到孔洞大的菌胶团内部，粒径大的被阻隔在网格之外，只能标记游离出菌胶团外部的微丝菌和菌胶团表面的微丝菌。据此，设计出不同尺寸的量子点探针和染料配合，探索了污泥网格尺寸的评价方法。利用密度泛函理论分析了DAPI和尼罗蓝分别荧光标记poly-P和PHA的结合关系和作用位点。用DAPI原位标记活性污泥中的poly-P，结合微丝菌形态特征，能够清晰表达出微丝菌体内的poly-P随微丝菌丰度的变化关系。结果发现，在微丝菌生长及爆发阶段，菌体内形成poly-P颗粒的能力最强，在微丝菌衰退阶段，形成poly-P颗粒的能力也随之衰弱。采用18碳酸对微硅粉进行了修饰，并在污泥膨胀状态下投加、观察投加后的系统内SVI的变化规律，结果表明，该种方式对污水处理系统污泥膨胀有良好的抑制作用。项目所制备探针和天津市某污水处理厂进行了初步合作，在污水处理厂活性污泥丝状膨胀快速检测方面由良好的应用前景。