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题名: 基于混凝的联合处理工艺对水中新兴污染物的去除效果和作用机理
作者: 姜巍1
学位类别: 博士
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 王东升
关键词: 新兴污染物,吸附,混凝,酶,联合工艺 ; Emerging Contaminants, Coagulation, Adsorption, Enzyme, Hybrid Processes
其他题名: Coagulation Based Hybrid Processes for Emerging Contaminant Removal: Performance and Mechanism
学位专业: 环境工程
中文摘要: 新兴污染物主要包括药物和个人护理用品(PPCPs)、内分泌干扰物(EDCs)、 表面活性剂、塑化剂及其它工业添加剂等。虽然新兴污染物在水环境中的存在浓 度非常低,而且大多数新兴污染物没有在相关法律法规中列出,但是新兴污染物 会对水生生物造成急慢性中毒、内分泌干扰、生物积累等多种影响。传统饮用水 处理工艺对于新兴污染物的去除效率很低,在某些情况下甚至没有去除效果,因 此,有必要对传统饮用水处理技术进行强化。本文构建了混凝与吸附、酶催化氧 化等组合的复合工艺,研究并探讨了其工艺可去除原理以及组合工艺之间的协同 去除机制。此外,水体中的天然有机物(NOM)和悬浮性固体(SS)等在新兴 污染物的去除过程中存在着复杂的相互作用,因此,本研究明确了 NOM和 SS 在对新兴污染物去除效果和降解过程的影响,以推动新兴污染物去除工艺原理的 建立与学科的发展。 本研究选取了碳纳米管(CNT)和超细粉末活性炭(SPAC)作为研究对象, 并对比了普通粉末活性炭(PAC)和颗粒活性炭(GAC),研究了其对水杨酸、 布洛芬和双氯芬酸这三种典型的新兴污染物的吸附效果。研究发现,比较四种吸 附剂对污染物的去除效果,基本上呈现出 SPAC>PAC>GAC>CNT的趋势。在不 同污染物之间,对双氯芬酸(DCF)的吸附容量最大。从污染物的性质中可以看 出,DCF的辛醇-水分配系数(logKow)在三种污染物中最高,疏水性更强。DCF 因为具有更强的疏水性,因此更有可能受到水的排斥而趋向于界面,克服水膜的 阻力,提高了吸附效率。溶液中的天然有机物( NOM)会对新兴污染物的吸附 造成不利影响。由于 NOM的粒径较大,更容易被大孔径的 CNT吸附,因而溶 液中 NOM浓度变化对 CNT的影响更大。 在对吸附法去除新兴污染物研究的基础上,本研究进一步采用一步法制备了 同时具有混凝及吸附性能的复配碳材料混凝剂,确定了最佳反应时间及吸附剂与 混凝剂的配比。研究表明,复配混凝剂相比起吸附剂和混凝剂单独使用时,对新 兴污染物的去除效果均有显著提升。SPAC和 CNT在与 PACl复配后,吸附容量 最高提升了 5倍以上;同时碳材料还可以在絮凝过程中起到架桥的作用,从而能 够提高絮凝剂的去除效率。NOM会产生竞争性吸附作用,并且会导致脱稳的胶 粒复稳以及絮体颗粒粒径的降低,所以对 ECs的去除有不利的影响。高 pH值对 形成大絮体颗粒有利,新兴污染物更易被大絮体颗粒吸附和卷扫,所以新兴污染 物的去除率随 pH升高而提高。三种新兴污染物的去除率基本上表现出 SALA
英文摘要: Emerging contaminants (ECs) generally consist of pharmaceutical and personal care products (PPCPs), endocrine disrupting chemicals (EDCs), surfactants, plasticizer and other industrial addictives. Although ECs are commonly found in the μg/L or ng/L concentration range in the water, they can cause a variety of effect on aquatic organisms and human health such as acute and chronic toxicity, endocrine disruption, bioaccumulation and biomagnifications. Traditional water treatment works are normally ineffective in treating the emerging contaminants, thus, it is vital to develop effective water treatment processes to remove ECs. In this study, coagulation based technics, including coagulation-adsorption and coagulation-enzyme catalyzed oxidation, are developed for ECs removal. The synergistic effect and removal mechanisms of the hybrid processes are discussed. Natrual organic matters (NOM) and SS, which are enormously presented in the natural water, are investigated for their roles such as competitive adsorption, complexing, and aggregated sedimentation in the hybrid processes for ECs removal. How NOM ans SS affect the removal efficiency and degradation pathways of ECs removal through coagulation based hybrid processes are systematically explored in this study. New types of adsorbents including carbon nano tube (CNT) and super powdered active carbon (SPAC) were selected as research target, with traditional adsorbents PAC and GAC as comparison. Adsorption effects were studied for the removal of three targeted emerging contaminants-salicylic acid, ibuprofen and diclofenac. Results showed that the adsorption capacities generally follow the trend of SPAC>PAC>GAC>CNT. Among different emerging contaminants, the adsorption capacity for DCF is the largest. From the contaminants characteristics, the log P of DCF is the largest of the three contaminants. Due to its highest hydrophobicity, DCF is more likely to be rejected from water and overcome the obstruction of the water film that presented in the surface of the particles. In this case, the adsorption capacity for DCF could be enhanced. The natural organic matter that ubiquitously presented in the water could cause negative effect on ECs adsorption. As the NOM particle size is relatively large, they are more likely to be adsorbed on the CNT, which has larger pore size. Thus NOM causes more impact on the CNT for removal ECs. On the basis of the study for ECs adsorption, we further developed a one-step method for preparing pre-mixed PACl and super powdered activated carbon (SPAC)/carbon nanotubes (CNT), which is a composite material that could act as the role of both adsorbants and coagulants. The optimal reaction time and adsorbants/coagulants ratio were defined. Pre-mixed PACl and super powdered activated carbon (SPAC)/carbon nanotubes (CNT) were employed for the removal of emerging contaminants (ECs) from various water sources. Salicylic acid (SALA), ibuprofen (IBP) and diclofenac (DCF) were the targeted ECs. The synergistic effect of combined coagulation and adsorption process as well as their individual removal performance were discussed in this study. The results of the three ECs removal indicate that pre-mixed PACl and SPAC/CNT have a better removal ability compared with PACl or SPAC/CNT alone. The maximum adsorption capacities increase at least 5 times after the addition of PACl, attributed to the charge neutralization and adsorption on the flocs. The removal efficiency of ECs by coagulation improves with the addition of SPAC/CNT as a result of the bridging effect as well as adsorption of ECs by carbon materials. The removal efficiency for these three ECs always exhibit as following trends: SALA (log P=1.98)
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38638
Appears in Collections:环境水质学国家重点实验室_学位论文

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作者单位: 1.中国科学院生态环境研究中心
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