饮用水处理工艺中微囊藻毒素污染调控技术的优化研究

发布时间：2018-01-22 01:10

本文关键词： 蓝藻水华微囊藻毒素饮用水处理污染调控技术优化　出处：《山东大学》2013年博士论文　论文类型：学位论文

【摘要】：蓝藻水华引发的微囊藻毒素(Microcystins, MCs)次生污染已成为全球关注的热点环境问题。MCs是水华藻类的次生代谢产物,属于环状多肽,细胞死亡或解体后大量释放到水体中,危害水质安全。MCs具有极高的细胞选择性和专一生物毒性,机体摄入后可经多种途径转移到肝脏等靶器官。毒素暴露后,肝细胞的氧化应激水平显著提高,同时伴生有DNA损伤、细胞骨架破坏、细胞凋亡现象。鉴于MCs对水环境安全及人类健康的危害,控制水体蓝藻水华和MCs浓度水平,确保饮用水安全供给已经成为科学工作者重点关注的环境问题。原水除藻(物理、化学、生物方式)、化学混凝、沉淀、过滤、消毒、活性炭吸附、生物降解等工艺陆续应用于MCs的调控并且获得了明显的成效。但是由于技术限制和认识不足,上述各类工艺尚难以从根本上调控MCs的产生、释放和毒性风险问题,仍然需要对受MCs污染的原水层层设防,逐级调控。本论文从蓝藻细胞低破损去除、含藻给水污泥减量化处理、MCs消毒副产物鉴定与毒性评价方面,优化了受蓝藻水华污染饮用水的处理工艺,为MCs的有效调控提供新的技术支持。论文主要包括以下五部分：论文第一章阐述了微囊藻毒素的理化特性、生成机制与污染现状；归纳了微囊藻毒素典型的生物毒性、作用机制、水质标准与检测方法；详细介绍了针对营养物质、针对水源地藻细胞/MCs和针对给水常规/深度处理中MCs调控策略与工艺进展。在文献综述的基础上分析了目前相关研究存在的问题,提出了基于蓝藻细胞低破损去除、含藻给水污泥减量化处理、MCs消毒副产物鉴定与毒性评价研究的饮用水微囊藻毒素污染调控技术。论文第二章针对混凝沉淀工艺过程中蓝藻细胞的破损与胞内毒素释放问题,通过模拟混凝沉淀工艺,评价了混凝药剂和工艺运行条件(搅拌速度、时间、静沉时间等)对蓝藻细胞及其代谢产物的去除效果,在此基础上考察蓝藻细胞代谢产物的释放规律,阐明蓝藻细胞的破损机理；并对混凝剂剂量、搅拌操作及絮体堆积时间等条件进行了优化。在优化后的混凝条件下(对AlCl3而言最优条件为15mg/L,快搅250r/min、1min,慢搅20r/min、20min;对PACl而言最优条件为4mg/L,快搅150r/min、2min,慢搅40r/min、30min),几乎所有铜绿微囊藻细胞都可通过表面电中和被完整去除,混凝剂的投加和搅拌条件并没有导致MCs的额外释放。AlCl3混凝絮体中,藻细胞表面能够形成一种有效保护层,一定程度上减弱了藻细胞的溶解。与AlCl3不同,PACl能够打破藻细胞外的保护层,显著加剧藻细胞的破损,使其在絮体堆置2天后即发生溶解。本研究不仅对传统饮用水混凝沉淀处理工艺中有效去除藻细胞具有重要意义,对于沉淀污泥处理过程中水资源的循环利用和二次污染防治同样具有重要的指导意义。论文第三章在混凝沉淀净化处理含藻原水工艺优化的基础上,进一步考察了含藻给水污泥真空过滤脱水过程中机械作用和理化作用对蓝藻细胞稳定性与MCs释放特性的影响。基于不同操作条件下过滤效率(过滤时间、平均滤速)、滤液浊度、MCs浓度的变化,明确了机械作用和理化作用对藻细胞完整性的具体影响,并据此对过滤操作条件进行优化。研究发现载样量对污泥脱水特性影响显著,污泥在过滤介质表面逐渐堆积,不仅降低滤速且对藻细胞具有明显的挤压破坏,实际操作中应避免污泥层的形成,以提高滤速同时减少MCs释放。含藻给水污泥过滤脱水时应选择亲水性过滤介质,在保证较高过滤效率的条件下尽可能降低介质孔度。尽管正压过滤效率略有提高,却会造成絮体和藻细胞破损,从减少MCs释放的角度来讲,应选择低破坏性的真空过滤技术。在合适的推动力作用下(高真空度),含藻给水污泥过滤效率较高且未增加滤液MCs浓度和浊度,应优先选择。污泥堆存时间的延长虽有利于提高污泥脱水效率,却显著提高了滤液MCs浓度和浊度。在实际给水厂含藻给水污泥减量化处理时,应控制严苛的堆存时间(AlCl3给水污泥要求堆存时间不超过4d, PACl给水污泥要求堆存时间不超过2d)。本研究完善了对蓝藻细胞胞内MCs的归趋方式的认识,同时具体研究结果能够为实际给水厂含藻给水污泥的减量化处理和含泥水资源化利用提供借鉴和参考。论文第四章以典型毒素MCLR和MCRR作为饮用水中微囊藻毒素调控研究的契入点,通过模拟常规氯消毒工艺条件,在实现MCs氧化去除的同时借鉴微囊藻毒素的传统制备工艺,实现MCs消毒副产物(MC-DBPs)的分离纯化,并利用液相色谱-质谱(LC/MS)、质谱-质谱联用(MS/MS)等技术对MCs及MC-DBPs进行结构对比解析,进而确定主要MC-DBPs的结构特性与生成机制；同时在色谱制备的基础上利用蛋白磷酸酶抑制毒性实验建立和完善MC-DBPs环境风险的评价方法。研究表明在不同消毒模式下,MCs能够稳定消减至WHO规定的限值(1.0μg/L)以下,但同时氧化生成多种MC-DBPs。典型DBPs产物类型与分布受MCs类型和消毒剂量的影响与制约。综合分析MC-DBPs的生成机制,不难发现MC主要经历Adda共轭二烯双键加成反应和部分初级产物的脱水反应。蛋白磷酸酶PP1的毒性抑制实验均证实多数MC-DBPs的生物毒性较原毒素有明显下降,但残余的生物毒性依然不能忽视。尽管消毒处理可有效调控MCs的浓度水平,但综合考虑MC-DBPs的含量变化和潜在生物毒性,MC-DBPs对饮用水的二次污染同样值得关注。本研究建立的针对MC-DBPs毒性分析评价技术并不局限于MCLR和MCRR,依据原水中MCs的分布特征,同样适用于其它类型毒素消毒副产物毒性的评价与调控。本研究有助于综合认识MCs的危害及其调控策略和提高饮用水质量,因而具有重要实际意义和应用价值。论文第五章对各研究部分进行了总结,并分析了“饮用水处理工艺中微囊藻毒素污染调控技术的优化研究”的优势与不足之处,展望了该领域的发展方向。本论文优化和改进了微囊藻毒素污染原水的常规处理工艺,为MCs的有效调控提供新的技术支持与参考。
[Abstract]:Microcystins cyanobacterial blooms caused by (Microcystins, MCs) secondary pollution has become a hot.MCs global environmental concern is the secondary metabolites of algae, which belongs to the cyclic peptides, cell death or after the collapse of a large number of release into the water, water quality and safety hazards of.MCs has high selectivity and specific cell toxicity, after intake of the body through multiple channels of transfer to the liver and other organs. The toxin after exposure, the levels of oxidative stress in liver cells increased significantly, while associated with DNA damage, cytoskeleton damage, cell apoptosis. In view of the MCs on the water environment safety and human health hazards, control water cyanobacteria and MCs concentration level, to ensure the safety of drinking water supply environmental problems have become the focus of scientific workers. The raw water algae (physical, chemical and biological methods), chemical coagulation, sedimentation, filtration, disinfection, activated carbon adsorption, biological The regulation of degradation process were used in MCs and achieved remarkable results. But due to technical limitations and inadequate understanding of the various types of technology is difficult to fundamentally control the generation of MCs, and the release of toxic risk problem, still need to MCs contaminated water layer uponlayer, step by step regulation. This paper from the cyanobacterial cells with low damage the removal of algae containing water treatment, sludge reduction, MCs disinfection by-products identification and toxicity evaluation, optimizing the treatment process by cyanobacteria contaminated drinking water, to provide new technical support for effective control of MCs. The paper mainly includes the following five parts:
The first chapter expounds the physicochemical characteristics of microcystins, formation mechanism and pollution; summarizes the biological toxicity of microcystin typical mechanism, water quality standards and testing methods; introduced for nutrients, water algae /MCs and conventional water treatment for MCs / depth control strategy and process progress. On the basis of literature review of existing related research questions, put forward the cyanobacterial cells with low damage removal based on the treatment of algae containing water sludge reduction, microcystins in drinking water pollution control technology of MCs disinfection by-products identification and toxicity evaluation research.
In the second chapter, damage problems and release of toxin in cyanobacterial cells coagulation sedimentation process, through the simulation of coagulation sedimentation process, evaluation of the coagulant and operating conditions (stirring speed, time, settling time etc.) on the removal of algae and its metabolites, releasing test cyanobacteria metabolites on this basis, clarify the damage mechanism of cyanobacterial cells; and the coagulant dosage, stirring and floc accumulation time were optimized. Under the optimized conditions of coagulation (for AlCl3 optimal conditions for 15mg/L, 250r/min 1min, fast mixing, slow stirring 20r/min, 20min for PACl optimal; the condition is 4mg/L, stirring 150r/min, 2min, 40r/min, 30min), slow stirring, almost all of Microcystis aeruginosa cells by surface charge neutralization is the complete removal of coagulant and stirring conditions did not lead to the amount of MCs The release of.AlCl3 coagulation floc, the algal cell surface to form an effective protective layer, to a certain extent, weakened the dissolution of algal cells. Unlike AlCl3, PACl can break the protective layer outside the cell, significantly increases the damage of algal cells, the flocs piled up 2 days' dissolution this research not only on the traditional drinking water coagulation process in the effective removal of algal cells has important significance, also has an important guiding significance for the treatment process of sludge water resource recycling and two pollution prevention.
In the third chapter, based on the coagulation treatment of raw water containing algae precipitation purification process optimization, to further investigate the effects of the mechanical process of algae containing water supply sludge dewatering by vacuum filter and physicochemical effects on the release characteristics of cyanobacterial cells. MCs stability and filtration efficiency under different operating conditions (based on the filtration time, average filtration rate). The filtrate turbidity, the MCs concentration, the effect of mechanical and physicochemical effects of specific effects on algal cell integrity, and thus to optimize the filter operation conditions. It is found that the effect of loading amount of sludge dewatering characteristics of sludge was gradually accumulated on the surface of the filter media, not only reduce the filtration rate and has obvious damage to the extrusion the algal cells, prevent the formation of sludge layer should be in the actual operation, in order to improve the filtering speed and reduce the release of MCs. The water containing algae sludge dewatering should choose hydrophilic filter media, in order to ensure a The high filtration efficiency as much as possible under the condition of reducing medium porosity. Despite the positive pressure filtration efficiency increased slightly, it will cause the flocs and cell damage, reduce the release of MCs from the point of view, should choose the low destructive vacuum filtration technology. In the driving force under suitable (high vacuum), algae containing water sludge with high filtration efficiency without increasing the filtrate MCs concentration and turbidity, should be preferred. Although the time prolonged sludge storage can improve sludge dewatering efficiency, but significantly improved the filtrate MCs concentration and turbidity. The water containing algae sludge reduction in the actual water supply plant, should control the stockpiling time demanding (AlCl3 water supply sludge requirements storage time is not more than 4D, PACl requirements of water supply sludge stockpiling time not more than 2D). This study was to improve the cyanobacteria cells MCs the fate of understanding of the way, at the same time the research result can actually give water containing algae The reduction and treatment of water sludge and the utilization of mud water resources provide reference and reference.
In the fourth chapter, taking the typical MCLR toxin and MCRR as the study of microcystins in drinking water regulation point, through the simulation of conventional chlorine disinfection process conditions, while achieving the MCs oxidation removal of microcystins from the traditional preparation process, the realization of MCs disinfection by-products (MC-DBPs) separation and purification, and the use of liquid chromatography mass spectrometry (LC/MS), MS (MS/MS) of the comparison and analysis of the structure of MCs and MC-DBPs technology, structure characteristics and formation mechanism and to determine the main MC-DBPs; at the same time based on the chromatographic preparation of protein phosphatase enzyme inhibition toxicity evaluation method to establish and perfect the MC-DBPs study showed that in the environmental risk. The different disinfection mode, MCs can stabilize the provisions of cut to the WHO limit value (1 g/L), but at the same time the oxidation of various MC-DBPs. typical DBPs product types and distribution by MCs type and dose of disinfection The impacts and constraints. The formation mechanism of MC-DBPs comprehensive analysis, it is not difficult to find MC mainly through Adda conjugated diene double bond addition reaction and dehydration reaction. Part of the primary products of protein phosphatase PP1 toxicity inhibition experiment confirmed the biological toxicity of most of the MC-DBPs was lower than that of the original toxin, but the toxicity of residual disinfection although still can not be ignored. Treatment can effectively control the concentration of MCs level, but considering the MC-DBPs content changes and potential biological toxicity, MC-DBPs two pollution of drinking water is also worthy of attention. This study established for MC-DBPs toxicity analysis evaluation technology is not limited to MCLR and MCRR, according to the distribution characteristics of MCs in raw water, the same for evaluation and regulation in other types of toxin DBPs toxicity. This study is helpful to harm and control strategy of a comprehensive understanding of MCs and improve the quality of drinking water, which is heavy It is of practical significance and applied value.
The fifth chapter summarizes the research, and analysis of the "optimization" of drinking water treatment of microcystin pollution control technology in the process of the advantages and disadvantages of the future development direction of this field. This thesis optimized and improved the conventional treatment process of microcystin contamination of raw water, provide technical support with the new reference for effective control of MCs.

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU991.2

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