饮用水处理中浮游动物携带微生物的形成机制与控制机理研究

Zooplankton may be attached by aquatic microorganism in drinking water treatment, which may cause potential risk to the biotic security of drinking water quality. Few investigations are performed in the filed of fundamental studies in China. In this project, the interaction mechanism and control of zooplankton as a carrier for aquatic microorganism are investigated to ensure water quality security according to the former achievements. The influencing mechanism of biotic security will be investigated and effective control approaches may be expected to establish. The following researches will be performed. Firstly, the response relation between microorganism associated with zooplankton and environmental species will be established by investigating the formation mechanism of zooplankton as a carrier for aquatic microorganism. Secondly, the effective methods，to measure bacteria attached to the surface or inner of zooplankton， will be erected by optimizing desorption agents and working conditions. Thirdly, the phototaxis of zooplankton as a novelty will be investigated under the condition of water treatment process. The control of zooplankton no appearance in water treatment unit will be established by using phototaxis effect combined with auxiliary approaches. Finally, the mechanism of zooplankton as a refuge of carried microorganism against disinfection will be researched and the release of living microorganism from zooplankton to water will be investigated so as to control its biotic risk by residual chlorine. The control,uisng disinfection and residual chlorine, of zooplankton as a carrier for aquatic microorganism will be optimized and the multiple safeguard will be erected in this project. The goal of this project is to put forward scientific proofs to resolve this problem in drinking water treatment.

饮用水处理中浮游动物作为微生物的携带载体，其对水质的生物安全造成潜在风险。在我国针对此问题的基础研究尚未系统开展。在前期研究工作的基础上，以浮游动物所携带微生物的水质生物安全保障为目标，对其生物安全性的影响机制进行探讨，研究有效的控制技术原理和技术基础。通过研究浮游动物携带微生物的形成机制，明确浮游动物体表或体内微生物的存在形式及其作用关系，建立外部水环境微生物与浮游动物所携带微生物之间的种属响应关系；通过筛选解吸附剂和优化控制条件，建立浮游动物所携带微生物的高效检测方法；以浮游动物的趋光特性研究为突破，建立水处理工艺条件下浮游动物穿透行为的控制方法；通过浮游动物对其所携带微生物的保护作用机理与未被灭活微生物向水中的释放机制及其余氯控制研究，优化消毒与余氯控制技术体系。通过研究，建立基于水质安全的"多级屏障"控制方法。项目研究为水处理领域该问题的相关理论与应用提供科学依据。

饮用水处理中浮游动物作为微生物的携带载体，其对水质的生物安全造成潜在风险。以浮游动物所携带微生物的水质生物安全保障为目标，首先开展了浮游动物携带微生物及其与环境微生物的响应关系研究，结果表明：浮游动物体表附着细菌主要来自环境水体，体表细菌主要附着在浮游动物体表几丁质结构的刚毛器官以及体节之间的节间膜上；浮游动物体内细菌主要由其捕食得到，主要位于浮游动物的中肠位置，附着在颗粒物上的细菌对于浮游动物摄食贡献大于水中自由细菌。针对目前国内外浮游动物携带微生物检测方法的缺陷，建立了解吸附剂进行浮游动物体表附着细菌脱附与离心力协同作用的体表微生物检测方法；建立了紫外线灭活水中自由细菌和浮游动物体表附着细菌前处理、冻融法与超声波联合作用破坏浮游动物体表、解吸附药剂与离心作用联合脱附浮游动物体内微生物的检测方法。研究明确了浮游动物在蓝光照射下表现出明显的正趋光性，在UV-A照射下表现出明显的负趋光性；研究并明确了水质条件如有机物浓度、浊度等对浮游动物趋光特性的影响及其响应关系；基于浮游动物的正趋光特性，提出了在水厂炭池清水区液面处布置蓝光对浮游动物泄漏进行控制的方法；基于其负趋光特性，研究并提出了在水厂沉淀池集水槽前布置UV-A对浮游动物泄露进行控制的方法。通过研究明确了在照射强度为70μW/cm2，辐照100min条件下，UV-C对浮游动物体表细菌可以实现100%失活；但由于紫外线穿透浮游动物而作用在体内细菌的难度较大，其体内细菌的灭活率仅为50%~70%；氯系消毒剂进入浮游动物的体内并灭活其体内细菌主要通过两种方式：摄食作用和渗透作用；对浮游动物体内微生物失活的氯（氯胺）剂量关系为Ct值控制在80 mg•min/L以上；消毒后未被灭活的浮游动物体内微生物复活率可达15%，为防止二次污染发生，建议水中消毒后余氯浓度控制在0.4mg/L以上。