【作者】 刘成；

【导师】 高乃云；

【作者基本信息】 同济大学 ， 市政工程， 2007， 博士

【摘要】 近年来，富营养化水体中藻类水华的发生已经成为一个世界性问题。水体富营养化产生的危害之一是微囊藻毒素的生成和释放，其中microcystin-LR（MC-LR）和microcystin-RR（MC-RR）是两种最为常见的藻毒素。本论文采用预氧化、粉末活性炭吸附、混凝和强化混凝工艺以及液氯消毒等工艺对两种常见的微囊藻毒素及藻类的去除特性和机理进行了研究，此外，还对上海市水源水中藻类和微囊藻毒素的状况进行了调查，初步研究了太阳光催化氧化对微囊藻毒素的去除效果、影响因素以及其对藻类的灭活和生长抑制作用。针对上海市水源地的首次系统调查结果表明，上海市两大水源地水中的藻类数目和微囊藻毒素浓度相对较低：两大水源地藻类数目基本在6～1000万个／L之间；黄浦江水中的总MC-LR浓度在0～250ng／L之间，总MC-RR浓度在0～650ng／L之间，且主要为溶解性毒素，而长江水中毒素浓度则更低，许多月份低于100ng／L的检测限，但形成原因各不相同。预氯化和高锰酸钾预氧化均可在一定程度上强化混凝工艺对藻类的去除效果。预氯化工艺非但不能有效降低细胞外微囊藻毒素浓度，反而会使藻细胞破裂释放出藻毒素；高锰酸钾预氧化虽然不能显著降低细胞外微囊藻毒素的浓度，但不会明显增加水中微囊藻毒素浓度，原因为高锰酸钾优先与水中的溶解性微囊藻毒素反应。粉末活性炭可以有效吸附去除水中的微囊藻毒素，10mg／L的粉末活性炭在40min内对MC-RR、MC-LR的去除率分别达到55％和45％；在一定初始浓度范围下，对于给定的吸附时间、活性炭投加量，在天然有机物存在的条件下，两种微囊藻毒素的去除效果与其初始浓度无关，应用孔表面扩散模型（PSDM）、理想吸附理论（IAST）及当量背景化合物理论（EBC）从理论上证明了这一结果；与以往的结果不同，粉末活性炭和氯同时投加时，氯会在一定程度上强化粉末活性炭对两种微囊藻毒素的吸附去除效果（20％左右），原因可能为粉末活性炭的表面官能团与氯作用生成羟基自由基，强化了对微囊藻毒素的氧化效果。对处于高藻期的原水，调节原水的pH值到6.0左右并投加10mg／L左右的粉末活性炭可以有效去除原水中的藻类，并保证其细胞的完整性，此外还可解决高藻水的藻嗅问题；强化混凝工艺可以明显提高细胞外微囊藻毒素的去除效果，去除率达到60～70％，去除机理主要在于强化混凝工艺条件下，微囊藻毒素分子结构中的羧基与水合金属离子形成溶解度相对较小的化合物，而这种化合物较易在混凝过程加以去除，对有机物的分级测定结果表明，强化混凝明显强化了对微囊藻毒素这类小分子弱疏水性有机物的去除；而强化混凝工艺不能强化对水中的阿特拉津和双酚A这类微量有机污染物的去除。游离氯对两种微囊藻毒素（MC-LR、MC-RR）具有一定的去除作用，两种微囊藻毒素的氯化降解过程均符合二级反应动力学模型，氧化过程与反应时间和游离氯浓度密切相关：在pH值为7.25时，将黄浦江水中10μg／L的MC-LR降低到国家水质标准中的要求值（1μg／L）所需要的CT值为101.88mgmin／L，较低的pH值有利于两种微囊藻毒素的氧化降解，原因为HOCl与微囊藻毒素分子之间的反应为游离氯氧化微囊藻毒素的主要途径；强化混凝+氯+氨联合消毒工艺在有效保证消毒效果的同时，显著降低了DBPs的生成量，该消毒工艺用于处理高藻水则可以有效去除水中的藻类细胞、细胞外微囊藻毒素。太阳光催化氧化工艺对饮用水中MC-RR、MC-LR两种微囊藻毒素有很好的去除效果，两种物质的降解过程均符合一级反应动力学模型；腐殖酸对太阳光降解水中微囊藻毒素具有促进和抑制的双重作用，在太阳光／腐殖酸体系中，腐殖酸可以催化微囊藻毒素的光降解，而在太阳光／腐殖酸／TiO₂体系中，由于腐殖酸吸收了大量的太阳光，减弱了照射到TiO₂上的光强以及腐殖酸本身可以与羟基自由基反应，从而弱化微囊藻毒素的光降解效果；溶解氧对太阳光催化氧化的效果具有显著的影响；太阳光催化氧化可以有效的杀灭水中已存在的藻类，而且可以有效抑制水源水中藻类的繁殖生长；太阳光催化氧化工艺还可以有效氧化去除水中的莠灭净、阿特拉津和双酚A等内分泌干扰物，而且去除效果与有机物本身的稳定性无关，进一步说明太阳光催化生成的自由基是氧化水中有机物的主要途径。更多还原

【Abstract】 In recent years, the occurrence of heavy cyanobacteria blooms in eutrophic fresh water has been a worldwide problem. One of the major problems caused by cyanobacteria is the producing and releasing of microcystins （MCs）, in which microcystin-LR and microcystin-RR are the two most common species. Pre-oxidation. powdered activated carbon （PAC） adsorption, coagulation and enhanced coagulation and disinfection process were studied in this paper to explore the removal characteristics and mechanisms of the two microcystins. in addition, removal effects and influential factors of solar catalyzed oxidation process to microcystins and algae were studied in the meantime.The quantity of algae and the content of microcystin in the Shanghai water sources are relatively low: the quantity of algae are between 60,000 and 10,000,000 per liter, the concentration of total MC-LR and MC-RR are 0-250ng/L and 0-650ng/L, respectively, in Huangpu river; as to Yangtz River source, the value are even lower than that.Both pre-chlorination and potassium permanganate pre-oxidation can improve the removal effect to algae by coagulation to some extent. However, they have some discrimination in the extra-cellar microcystins’ removal. Pre-chlorination can’t reduce the concentration of extra-cellar microcystins but increase it to some certain extent. Potassium permanganate can’t increase the concentration of extra-cellar microcystins, for it can oxidize microcystins prior.Powdered activated carbon can effectively remove microcystins from natural waters, the removal rate can reach 45% and 55% for MC-LR and MC-RR, respectively, at PAC dosage of 10mg/L. The removal percentage of microcystins at any contact time and at any PAC dose were observed to be independent of the initial microcystins concentration when the initial concentrations were below some given concentration. Equation derived from pore surface diffusion model （PSDM）, ideal adsorbed solution theory （IAST） and equivalent background compounds （EBC） validated this result; Chlorine can enhance the removal effect of PAC to microcystins（about 20%）, which was contrary to the former results in literatures; the reason may be lied in that the OH radicals produced through the way of reaction between PAC and chlorine.To high-algae raw water, adjusting the pH to 6.0 and adding 10mg/L PAC can remove algae effectively and keep the cellar intact, it can also resolve the problem of "algae-odour" in high algae water. Enhanced coagulation can improve the removal effect of extra-cellar microcystins obviously, of which removal rate was 60～70% and the removal mechanism mainly lies in that the carboxyl in microcystin molecular structure can form some compounds with metal hydrate at the condition of enhanced coagulation and these compounds can be easily removed in the process of coagulation. Enhanced coagulation can’t enhance the removal of some trace SOCs such as atrazine and BPA, which doesn’t has carboxyl group.Free chlorine can remove two kinds of microcystins to some extent, and the degradation process in aqueous solution followed second-order kinetics, which related closely with reaction time and free chlorine concentration. CT value was at least 101.88 mg L^-1 min at pH 7.25 to reduce 10μg/L microcystins to the national standard of 1μg/L, which is higher than normal CT value for disinfection; Acidic pH condition favored the degradation of the two kinds of microcystins, for the reaction betw（?） HOCl mocecular and microcystins are the main pathways of all reactions. Enhanced coagulation combined with chlorine and ammonia disinfection significantly decreased the production of DBPs, and ensured a good disinfection effect. The process could effectively remove alge and microcystins in water.Sunlight-indued catalytic oxidation has a good removal effect both on MC-RR and MC-LR. The degradation process of two substances followed pseudo-first order kinetics well. Humic acids had both improving and retardant effects on the degradation process. Microcystins removal was improved in sunlight/HA system, whereas it was retarded in sunlight/HA/TiO₂ system. Because HA adsorbed partial sunlight, which decrease the light intensity used by TiO₂ and OH radicals thereafter. And HA could react with OH·also. Sunlight-induced catalytic oxidation could inactivate algae in water efficiently, and control the production of algae in water resources. Furthermore, it could oxidize EDCs substances such as ametryn, BPA and atrazine. The removal efficiency is unrelated with the structure of organic substance, which suggest the OH·reaction is the main degradation pathway.更多还原