【作者】 李潇潇；

【导师】 张跃军；

【作者基本信息】 南京理工大学 ， 化学工程与技术， 2012， 博士

【摘要】 聚二甲基二烯丙基氯化铵(PDMDAAC)是一种阳离子高分子聚合物,具有正电荷密度高、相对分子量易于控制、无毒等优点,在水处理领域的应用受到了广泛关注。本文应用具有高相对分子质量,且相对分子质量系列化的PDMDAAC,研究稳定型无机盐/PDMDAAC复合混凝剂的制备工艺,复合混凝剂的强化混凝机制,针对几种我国典型的微污染地表原水的地域和季节特征,研究适用于微污染原水处理的复合混凝剂强化混凝处理工艺。通过系统研究,获得了以下4个方面进展。第一、系列稳定型无机盐/PDMDAAC复合混凝剂的制备针对高特征黏度的PDMDAAC在与无机混凝剂工业品复合过程中溶解困难、易产生沉淀、不能得到稳定复合混凝剂的难题,研究得到以高且系列化相对分子质量的PDMDAAC和无机混凝剂聚合氯化铝(PAC)、硫酸铝(AS)或聚合硫酸铁(PFS)为原料的3个系列复合混凝剂及其可工业化制备工艺。复合混凝剂具有以下特点：所含无机组分和杂质的量符合无机混凝剂国标,PDMDAAC占无机混凝剂的质量分数(w%)为5%-20%可调,相对分子量以特征黏度值([η])计为0.5～3.5dL/g可调；复合混凝剂常温贮存稳定期1年以上。由此,为复合混凝剂的实际应用与强化混凝机制研究打下基础。第二、复合混凝剂及其组分在强化混凝过程中的作用机制针对复合混凝剂的强化混凝机制问题,设计了相对独立考核复合混凝剂及其组分的电中和和吸附架桥这两种能力的方法,以混凝烧杯实验快速搅拌后高岭土颗粒的zeta电位和絮凝沉降实验中硅藻土絮团的沉淀速率为考核指标,研究了以PAC/PDMDAAC为代表的复合混凝剂及其组分对悬浮胶体的电中和能力和对凝聚物的吸附架桥能力。结果表明：复合混凝剂对悬浮胶体的电中和能力比PAC明显增强,且随所含PDMDAAC w%增加而提高,但不随PDMDAAC [η]值发生明显变化。使用复合混凝剂可明显提高硅藻土絮团的直径和沉降速率,且随PDMDAAC的[η]值或w%的增加而增加。由此发现,PDMDAAC可增强PAC的电中和和架桥能力,但是,复合混凝剂电中和作用的强化主要来自于PDMDAAC的w%,而架桥作用的强化则主要来自于PDMDAAC特征黏度[η]大小针对水质对复合混凝剂强化混凝作用影响规律的问题,设计了有浊度和CODMn两个主要参数的模拟微污染原水体系,以高岭土和腐殖质含量分别调控模拟原水浊度和CODMn,通过混凝烧杯实验系统考核了以PAC/PDMDAAC为代表的复合混凝剂对不同水污染特征和程度的模拟原水的强化混凝脱浊、电中和和架桥效果,关联了水质变化对复合混凝剂强化混凝效能的影响规律。结果表明：随着原水污染程度(浊度、CODMn)增大,复合混凝剂强化混凝作用变得显著,PDMDAAC w%和[η]值的提高,即电中和和架桥能力的提高能更好地体现出复合混凝剂强化混凝效果的优势。由此,复合混凝剂强化混凝机制的研究为微污染原水高效强化处理工艺提供了坚实的理论支撑和有效的技术途径。第三、典型微污染原水的强化混凝工艺针对冬季不同种类宁波内河水,四季长江水,以及冬夏季节太湖水等几种我国典型微污染原水的处理难题,通过现场混凝烧杯试验,研究了复合混凝剂强化混凝工艺对沉淀出水浊度去除的效能,结果如下：对于温度10℃以下,浊度仅为1.5NTU左右水质优良的冬季白溪水库水,水中颗粒物和有机污染物少,所带电荷少,无机盐/PDMDAAC复合混凝剂不适宜用于对其的强化混凝处理。在无机混凝齐(?)PAC、AS、和PFS中,水解产物相对密度较大,但比表面积最大的PFS脱浊效果好。就冬季微污染的宁波北渡河水和姚江水而言,原水呈微污染特征,水中胶体颗粒物以有机污染物为主。对温度为8-13℃,浊度为6-13NTU的北渡河水,要达到2NTU的水厂沉淀池出水浊度标准,AS、PAC、PFS需6.0～9.0mg/L的投加量,而AS/PDMDAAC、PAC/PDMDAAC和PFS/PDMDAAC复合混凝剂相对于原有无机混凝剂能减少8.33%～41.18%的投加量。对温度为8-13℃,浊度为7～10NTU的姚江水,要达到1.2NTU的水厂沉淀池出水浊度的要求,AS、PAC、PFS需5.0～10.0mg/L的投加量,复合混凝剂相对于原有无机混凝剂能减少7.76%-53.33%的投加量。就不同季节长江水而言,原水中颗粒以泥沙质为主,秋季长江水污染相对重,冬季和夏季长江水分别存在低温和高浊度的问题,春季长江水污染相对轻微,处理各有难易。长江沿岸水厂要求沉淀池出水在6NTU,在使用无机混凝剂使沉淀出水浊度达到这一要求的投加量下,AS/PDMDAAC、PAC/PDMDAAC禾(?)PFS/PDMDAAC复合混凝剂处理不同季节长江水时相对于无机混凝剂可使沉淀出水浊度降低幅度为：秋季14.41%-61.72%,冬季6.11%-58.50%,夏季5.31%-37.56%,春季4.19%～39.26%；要使沉淀出水达到6NTU的浊度要求,复合混凝剂相对于无机混凝剂减少投加量幅度为：秋季7.41%～37.04%,冬季2.50%～37.50%,夏季2.03%～27.20%,春季0.88%～27.16%；各系列复合混凝剂强化混凝脱浊效果强弱依次为：PAC/PDMDAAC>AS/PDMDAAC>PFS/PDMDAAC。复合混凝剂对无机混凝剂混凝效果改进幅度与按长江水质季节污染程度相同,依次为：秋季、冬季、夏季、春季。就冬、夏季太湖原水而言,不仅受有机物、藻污染,而且季节特征明显。对于冬季低温微污染含藻太湖原水,无机混凝剂混凝脱浊效果优劣依次为：PAC>AS≈PFS,在使用与无机混凝剂使沉淀出水浊度达到2NTU的太湖沿岸水厂沉淀池出水浊度标准的相同投加量下,AS/PDMDAAC、PAC/PDMDAAC(?)目对于与AS、PAC分别可降低沉淀出水浊度33.33%～62.50%、20.33%～56.22%；要使出水浊度达到2NTU的浊度标准,AS/PDMDAAC、PAC/PDMDAAC分别可减少无机混凝剂投加量18.65%-56.15%、9.42%～23.48%。对夏季高藻微污染太湖原水,各无机混凝剂脱浊效果优劣依次为：AS>PAC>PFS,在使用与无机混凝剂使沉淀出水浊度达到2NTU的相同投加量下AS/PDMDAAC、PAC/PDMDAAC(?)目对于与AS、PAC分别可降低沉淀出水浊度39.67%-82.45%、45.33%-84.90%；要使出水浊度达到2NTU的浊度标准,AS/PDMDAAC、PAC/PDMDAAC分别可减少无机混凝剂投加量20.18%-56.52%、28.15%～56.59%。由此,复合混凝剂对受污染较重的夏季太湖原水的强化混凝效果更好。另外,对冬、夏季太湖原水,复合混凝剂能够取代无机混凝剂加预加氯的组合工艺的强化功能,其应用可望大幅减少氯消毒副产物生成,提高供水水质安全性。由上述现场混凝烧杯实验证实：复合混凝剂相对于无机混凝剂可大幅提高混凝脱浊效果；达相同水厂要求的沉淀池出水浊度时减少无机混凝剂投加量；复合混凝剂强化混凝效能随原水微污染程度的增大而增大；复合混凝剂中PDMDAAC的w%和[η]值越高,强化混凝效能越强。复合混凝剂的应用不仅可以为现有水厂制水工艺减少混凝剂投加量、提高沉淀出水水质、增大出水产量、提高生产效率,而且可为其未来原水的深度处理制优质水提供技术准备。由此,对典型微污染原水的强化混凝工艺研究为复合混凝剂走向工业化应用奠定了基础。第四、强化混凝工艺的生产试用和中试放大对复合混凝剂强化混凝工艺在长江沿岸的某水厂进行了生产试用研究。结果表明：对浊度25～40NTU,水温15-20℃的长江水,当日均12万t处理水量下,沉淀出水浊度满足水厂工艺要求时,复合混凝剂相对于现有混凝剂PAC可起到相同投加量下降低沉淀出水浊度并能耐50%水量突增冲击、达到相同沉淀出水浊度时减少约5%-35%混凝剂投加量的效果,现场烧杯实验结果成功在生产线上得到放大。在太湖沿岸水厂的日均120t规模中试制水生产线上进行了复合混凝剂强化混凝工艺全程中试放大和稳定运行实验。结果表明：复合混凝剂相对于无机混凝剂在相同沉淀出水浊度下减少投加量、与无机混凝剂相同投加量下降低出水浊度、沉淀出水浊度达深度处理要求时提高沉淀出水水质和水量突增时保证出水水质等强化混凝效能,在中试生产线上得到成功放大,复合混凝剂强化混凝工艺可连续24h以上稳定运行。由此,强化混凝工艺的放大研究为复合混凝剂的工业应用奠定了基础。更多还原

【Abstract】 Poly-dimethyldiallylammonium chloride (PDMDAAC) is a typical cationic polymer. It has attracted widely attention in water treatment areas because of its characters of high positive charge density, easy controlled molecular weight, no toxicity. In this dissertation, the preparation processes for stable inorganic salt/PDMDAAC composite coagulants using PDMDAAC with high molecule weight and series molecule weight as coagulation-aid agents were developed, then the enhanced coagulation mechanisms using composite coagulants were studied preliminary. Based on the regional and seasonal feature of several kinds of typical tiny-polluted raw water, the enhanced coagulation processes using composite coagulants were investigated. The obtained main research progresses are showed as following.The preparation of steady composite coagulantsTo overcome the difficulty in preparing homogenous solution of inorganic coagulants with organic coagulant-aid agent PDMDAAC with high molecule weight, the composite coagulant preparation processes which was suited to industry production were developed. Three series of composite coagulants were prepared through using inorganic coagulants including Poly-Aluminum Chloride(PAC), Aluminum Sulfate(AS) and Poly-Ferric Sulfate(PFS), and organic coagulant-aid agent PDMDAAC with high molecule weight and series of molecule weight (represented as intrinsic viscosity) as raw materials. The composite coagulants have features as following:the content of inorganic component and contained impurities were corresponding the requirements of Chinese national standards of inorganic coagulants, the mass ratio of PDMDAAC to the inorganic coagulants in composite coagulants was5%-20%. and the intrinsic viscosity of PDMDAAC was0.5～3.5dL/g. The storage term of composite coagulants was more than1year under room temperature. Based on above, the foundations for the application of composite coagulants and the studies of their enhanced coagulation mechanisms were established.Enhanced coagulation mechanism of composite coagulantsAbout the enhanced coagulation mechanisms of composite coagulants, the Jar test for kaolin suspension and the settlement test for diatomite suspension under specifically condition were designed to study the charge neutralization and bridge ability of both composite coagulants and their components. The test using PAC/PDMDAAC composite coagulants was as a representative case. The results showed that in the Jar test, the charge neutralization ability of composite coagulants was higher than that of PAC, and increased with the higher content of PDMDAAC, but not with the change of intrinsic viscosity of PDMDAAC obviously. In the settlement test, the settling velocity and size of flocs of using composite coagulants increased remarkably with the increase of intrinsic viscosity or mass ratio of PDMDAAC, compared with that of using PAC. Therefore, it was found that the charge neutralization ability of composite coagulants was depended on the content of PDMDAAC, and the bridge ability of composite coagulants was depended on the intrinsic viscosity of PDMDAAC.About studies on the influences of raw water quality on enhanced coagulation effect of composite coagulants, the tiny-polluted stimulated raw water samples with different turbidity and CODMn values were formulated by adding kaolin and humus in tap water for jar tests. The results showed that under the selected coagulation conditions and ranges of simulated raw water quality, the enhanced coagulation effect of composite coagulants increased with the increase of the pollution level characterized by the value of turbidity and CODMn.Especially, the increasing of mass ratio or intrinsic viscosity of PDMDAAC in composite coagulants, which could increase ability of charge neutralization or bridge of composite coagulants, could largely enhance the coagulation effect of composite coagulants for polluted stimulated raw water.The above studies have offered a reliable theory support and an effective technology for enhanced treatment of tiny-polluted raw water.Enhanced coagulation processes using composite coagulants for several typical tiny-polluted watersFor several typical tiny-polluted raw water like net river water in Ningbo, Yangtze River water near Nanjing city in4seasons, and Taihu water near Wuxi city in winter and summer seasons, the jar tests in situ were conducted to study the performance of the enhanced coagulation process using composite coagulants under the similar coagulation condition with conventional coagulation processes used in local potable water plants. The results are showed as following.For low-turbidity and temperature Baixi reservoir raw water with turbidity of1.5NTU and temperature below10℃, the inorganic coagulants/PDMDAAC composite coagulants did not improve the turbidity removal compared with inorganic coagulants, so it could not be used for the enhanced coagulation for Baixi reservoir raw water. PFS single could get satisfying turbidity removal effect, so it could be used as a coagulant for the Baixi reservoir raw water.For net river water in Ningbo including Beidu River raw water and Yaojiang River raw water with characteristics of tiny-pollution, the suspended particles in the raw water adsorbed a certain content of organic compounds. For the Beidu River raw water in winter with temperature of8～13℃and turbidity of6～13NTU, the dose of6.0～9.0mg/L of AS, PAC and PFS were required respectively, when residual turbidity of2NTU should be achieved. But, the corresponding composite coagulants of them could decrease the inorganic coagulants dose by8%～40%respectively. For low-turbidity Yaojiang raw water with temperature8～13℃and turbidity of7～10NTU, the dose of5.0～10.0mg/L for AS, PAC or PFS were necessary for treatment to reach residual turbidity of1～1.2NTU. But, the corresponding composite coagulants of them could decrease the inorganic coagulants dose by7.76%～53.33%respectivelyFor Yangtze River water in four seasons, the suspended particles in water were mainly composed of fine sediments. The tiny-polluted level of raw water in autumn was usually higher than that in spring, the water temperature in winter was low and the water turbidity in summer was high, which all caused difficulties in treatment. Using the similar doses for inorganic coagulants to reach the residual turbidity of6NTU, which was required by the potable water plants located in Yangtze River basin, the decrease of residual turbidity using composite coagulants compared with using inorganic coagulants were as following:14.41%～61.72%in autumn,6.11%～58.50%in winter,5.31%～37.56%in summer and4.19%～39.26%in spring. When the same residual turbidity of6NTU was achieved, the decrease of dose using composite coagulants compared with using inorganic coagulants were as following:7.41%～37.04%in autumn,2.50%～37.50%in winter,2.03%～27.20%in summer and0.88%-27.16%in spring. The turbidity removal ability of composite coagulants were in the order:PAC/PDMDAAC>AS/PDMDAAC>PFS/PDMDAAC The improvement effect of composite coagulants on inorganic coagulants for Yangtze River raw water in four seasons was as following:autumn>winter>summer>spring.For Taihu Lake raw water in winter and summer which was polluted mainly by organic compounds and algae, the season characteristic of raw water quality was obvious. For the Taihu Lake raw water in winter with characteristics of low temperature, containing algae and tiny organic pollution, the turbidity removal effects of inorganic coagulants were in the order:PAC>AS≈PFS. Using the similar doses for inorganic coagulants to reach the residual turbidity of2NTU, which was required by the potable water plants located in Taihu lake basin, using AS/PDMDAAC、PAC/PDMDAAC composite coagulants could decrease residual turbidity by33.33%～62.50%,20.33%～56.22%, compared to using AS, PAC, respectively. When residual turbidity of2NTU was achieved, using AS/PDMDAAC、PAC/PDMDAAC could decrease doses by18.65%～56.15%.9.42%～23.48%, compared to using AS, PAC, respectively. For the summer Taihu Lake raw water with the characteristics of high algae and organic pollutant content, the turbidity removal effects of inorganic coagulants were in the order:AS>PAC>PFS. Using the similar doses for inorganic coagulants to reach the residual turbidity of2NTU, using AS/PDMDAAC. PAC/PDMDAAC composite coagulants could decrease turbidity of supernatant by39.67%～82.45%.45.33%～84.90%, compared to using AS、PAC, respectively. When same residual turbidity of2NTU should be achieved, using AS/PDMDAAC. PAC/PDMDAAC could decrease dose by20.18%～56.52%,28.15%～56.59%, compared to using AS, PAC, respectively. Therefore, the enhanced coagulation effect of composite coagulants on Taihu lake water in summer was higher than that in winter. Especially, the enhanced coagulation processes using composite coagulants were able to replace the function of pre-chlorination combined with inorganic coagulants in turbidity and algae removal, resulting in the improvement of the potable water security by decreasing the formation of disinfection by-products.The above Jar tests results in situ have demonstrated that for tiny-polluted raw water, the composite coagulants could improve the turbidity removal effect and decrease inorganic coagulants dose greatly under the conventional coagulation process condition. The effect of enhanced coagulation of composite coagulants was increased with the increase of intrinsic viscosity or mass ratio of PDMDAAC, and the higher pollution level of raw water, the higher effect was. Meanwhile, composite coagulants could not only obviously decrease the coagulants dose, improve the water quality of supernatant and increase the volume of water production, but also could offer an effective technology for advanced treatment of raw water in future. Therefore, based on above Jar tests results in situ, the foundations of industrializing application of composite coagulants and their enhanced coagulation processes were established.Scaled-up tests of enhanced coagulation process using composite coagulantsThe scaled-up tests in potable water plant were conducted to evaluate the effect of enhanced coagulation process using composite coagulants in treatment for Yangtze River raw water. The results showed that for the Yangtze River raw water with temperature of15～20℃and turbidity of25～40NTU in spring, the composite coagulants functioned well in the ability of decreasing residual turbidity and inorganic coagulants doses when used in the potable water plant with the production capability of120000t/d. Using the similar doses for conventional coagulation process using inorganic coagulants to reach the required residual turbidity, the enhanced coagulation process using composite coagulants could reach much lower residual turbidity. When required residual turbidity was reached, the enhanced coagulation process could decrease dose by5%-35%compared with conventional coagulation process. At the same time, the enhanced coagulation process could be able to endure strange impact of50%water amount increase than conventional coagulation process did. The enhanced coagulation processes using composite coagulant obtained from jar tests were scaled up successfully in the potable water plant.The scaled-up tests in pilot-plant with production capability of4t/h were conducted to evaluate the magnification effect and running stability of enhanced coagulation processes for treatment of tiny-polluted Taihu raw water. For tiny-polluted and algae-contained Taihu Lake raw water, the enhanced coagulation effects of composite coagulants, including the enhancement of turbidity and algae removal, the decreasing of inorganic coagulants dose and the advanced treatment process in the future, were scaled up successfully in the pilot plant. Meanwhile, these enhanced coagulation processes could be steady operated.The above scaled-up test results have demonstrated that the composite coagulants and their enhanced coagulation processes could be directly applied in industry.更多还原