预氧化对含蓝藻水生物稳定性的影响及作用机理

The pre-oxidation process is utilized frequently for enhancing algae removal in drinking water treatment plant when the reservoir water or lake water is used as source water since cyanobacterial blooms occurred widely in those waters. However, the pre-oxidation process may decrease the biostability during the treatment of water containing cyanobacteria. The present proposal is to study the effect of oxidation products on biostability during pre-oxidation of water containing cyanobacteria, which would be performed by advanced instruments such as flow cytometry and high resolution mass spectrometry, and the final target is trying to control the formation of assimilable organic carbon (AOC) and pathogen growth potential (PGP) during the pre-oxidation of water containing cyanobcateria and derived organic matter by common used oxidants. The research works would concentrate on: (1) Explore the variation kinetics of AOC and PGP during the pre-oxidation of water containing cyanobacteria and derived organic matter by common used oxidants, establishing the kinetic model and uncovering the influence of pre-oxidation on the biostability of water containing cyanobacteria, clarifying and optimizing the process conditions and operating parameters, and to determine the optimal control strategy. (2) Figure out the composition, structural characteristics and functional groups of intermediates, as well as their transformation processes; and the relationships between intermediates' characteristics and AOC (PGP) concentration would be explored and quantitative model would be established. (3) The mechanism of AOC (PGP) formation in the oxidation process would be discussed by ways of detecting cyanobacterial activity and membrane integrity, as well as mass balance calculation. This study is helpful for providing scientific understanding and methods to inhibit the potential biological risks from the pre-oxidation of water containing cyanobacteria, and lay a foundation for improving drinking water safety.

蓝藻的大规模爆发促使以水库和湖泊作为水源的净水厂采用预氧化工艺来强化除藻，而预氧化处理蓝藻水可能导致水质生物不稳定。本项目以蓝藻预氧化产物对饮用水生物稳定性的影响为切入点，以流式细胞仪和高分辨率质谱等现代分析仪器为手段，以控制预氧化处理蓝藻水过程可同化有机碳（AOC）和病原菌生长潜能（PGP）的形成为目标，重点研究：（1）解析常用氧化剂处理蓝藻及衍生有机物过程AOC和PGP的变化动力学，建立动力学模型，揭示预氧化对含蓝藻水生物稳定性的影响规律，优化确定工艺条件和操作参数，提出预氧化工艺的最佳控制策略；（2）解析氧化过程产物的组成、结构和官能团的转化规律，建立氧化产物特征参数与AOC、PGP含量的定量模型；（3）解析氧化过程藻细胞的膜完整性和活性变化，结合产物质量衡算阐明AOC和PGP的转化机理。以上研究将为有效抑制预氧化含蓝藻水引起的生物风险提供科学依据和方法手段，提高饮用水生物安全性。

本课题以铜绿微囊藻为研究对象，对藻类有机物进行特性表征；研究了各种因素对氧化处理含蓝藻水AOC形成的影响；解析了氧化过程AOC的形成规律；通过检测氧化过程藻细胞膜完整性，藻细胞活性，有机物结构的变化，对AOC变化机理进行了剖析。主要成果如下：（1）探明了藻类有机物的特性，EOM主要由可溶性生物代谢产物构成，AOC含量低；IOM含有四个荧光基团，包括芳香结构蛋白、可溶性生物代谢产物、类腐殖酸和类富里酸有机质，其AOC含量高。（2）阐明了各种预氧化方式对含蓝藻水生物稳定性的影响规律，采用氧化处理含藻水时，AOC的形成按由难到易排序为：高锰酸钾<UV<氯<二氧化氯<臭氧<臭氧/过氧化氢，高锰酸钾是一种较优的预氧化方式。（3）诠释了藻类有机物结构和AOC的关系，氧化后芳香结构蛋白质和可溶性生物代谢产物逐渐被氧化，胞外DOC增加，SUVA值不断增大，有机物分子量降低，AOC含量增加。（4）揭示了氧化处理含蓝藻水对饮用水生物稳定性影响的机理，AOC的变化主要是由于藻细胞被破坏，IOM 释放造成的；氧化藻类有机物导致结构变化，对AOC 浓度增加也具有一定作用。以上研究成果为优化了预氧化剂的投加方式和投加量提高了科学依据，能提高饮用水生物稳定性，保证居民饮水安全。