环境科学  2019, Vol. 40 Issue (11): 4996-5001   PDF    
引用本文
王博东, 薛文静, 吕永涛, 苗瑞, 马百文. 微塑料对短流程膜工艺中膜污染的影响[J]. 环境科学, 2019, 40(11): 4996-5001.
WANG Bo-dong, XUE Wen-jing, LÜ Yong-tao, MIAO Rui, MA Bai-wen. Effects of Microplastics on Membrane Fouling During a Shortened Ultrafiltration Membrane Process[J]. Environmental Science, 2019, 40(11): 4996-5001.
微塑料对短流程膜工艺中膜污染的影响
王博东1,2,3, 薛文静2,4, 吕永涛1,3, 苗瑞1,3, 马百文2     
1. 西安建筑科技大学环境与市政工程学院, 西安 710055;
2. 中国科学院生态环境研究中心, 中国科学院饮用水科学与技术重点实验室, 北京 100085;
3. 陕西省膜分离重点实验室, 西安 710055;
4. 青岛科技大学环境与安全工程学院, 青岛 266042
收稿日期: 2019-03-19; 修订日期: 2019-06-14
基金项目: 国家自然科学基金青年科学基金项目（51608514）；陕西省重点产业链（群）项目（2017ZDCXL-GY-07-01）；陕西省重点科技创新团队计划项目（2017KCT-19-01）
作者简介: 王博东(1995~), 男, 硕士研究生, 主要研究方向为膜应用及膜污染控制, E-mail:17391059526@163.com
通信作者: 马百文, E-mail:bwma@rcees.ac.cn
摘要: 微塑料作为新型污染物越来越受到关注.随着微塑料在饮用水源地逐渐检出，亟需了解当前水处理工艺对其去除效能与机制.随着膜法饮用水处理技术的发展，短流程膜工艺以其占地面积小、去污效能高成为重要研究方向.因此，考察了微塑料对短流程膜工艺尤其膜污染的影响.结果表明，微塑料混凝前后，滤饼层始终是引起膜污染的关键诱因.超滤膜由于孔径小（d < 0.1 μm），微塑料（d < 5 mm）本身不会引起严重膜污染.然而，与铁盐混凝后，由于絮体的存在使得滤饼层相对疏松，但随着混凝剂投量增加，小粒径微塑料容易进入絮体形成的网络空间，形成致密滤饼层，严重加剧膜污染.pH 7.0时0.1 mmol·L-1和0.9 mmol·L-1 FeCl3·6H2O水解絮体导致的膜比通量分别为0.82和0.76.然而，0.1 g小粒径微塑料（d < 0.5 mm）分别与0.1 mmol·L-1和0.9 mmol·L-1 FeCl3·6H2O混凝后导致的膜比通量分别降低至0.76和0.62.此外，水环境中微塑料多呈负电.与碱性环境相比，氯化铁水解絮体在酸性环境中呈正电且粒径较小，微塑料容易被絮体吸附、捕获，进而形成相对致密滤饼层，引起严重膜污染.pH 6.0和8.0时，0.1 g小粒径微塑料（d < 0.5 mm）与0.3 mmol·L-1 FeCl3·6H2O混凝后膜比通量分别为0.55和0.79.
关键词: 微塑料      铁盐      超滤      短流程膜工艺      膜污染     
Effects of Microplastics on Membrane Fouling During a Shortened Ultrafiltration Membrane Process
WANG Bo-dong1,2,3 , XUE Wen-jing2,4 , LÜ Yong-tao1,3 , MIAO Rui1,3 , MA Bai-wen2     
1. School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China;
2. Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;
3. Key Laboratory of Membrane Separation of Shaanxi Province, Xi'an 710055, China;
4. College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
Abstract: Microplastics have garnered much attention worldwide as a new emerging pollutant. As they are gradually detected in freshwaters, understanding how microplastics will behave during current drinking water treatment processes is urgently needed. In recent years, the shortened process with an ultrafiltration (UF) membrane has shown excellent performance because of its low land use and high water purification efficiency. In this work, the membrane performance induced by microplastics was investigated with a shortened UF membrane process. The results showed that membrane fouling was always induced by the cake layer before and after coagulating with microplastics. Owing to the small UF membrane pore size (d < 0.1 μm), slight membrane fouling was caused by microplastics (d < 5 mm) alone. However, although the loose cake layer was formed because of the existence of flocs, the cyberspace formed by flocs was easily entered by small microplastics with increasing coagulant dosage. As a result, server membrane fouling was induced because of the formation of a dense cake layer. It was shown that the specific membrane flux induced by flocs alone was 0.82 and 0.76 in the presence of 0.1 mmol·L-1 and 0.9 mmol·L-1 FeCl3·6H2O, respectively. However, after coagulation the specific membrane fouling induced by the 0.1 g small microplastics (d < 0.5 mm) was 0.76 and 0.62 with 0.1 mmol·L-1 and 0.9 mmol·L-1 FeCl3·6H2O, respectively. In addition, microplastics were always negatively charged in water. In comparison with alkaline conditions, Fe-based flocs were positively charged under acidic conditions, which were also much smaller. Therefore, microplastics were more easily adsorbed by Fe-based flocs under acidic conditions, leading to severe membrane fouling because of the dense cake layer formed. After coagulating with 0.3 mmol·L-1 FeCl3·6H2O, the specific membrane flux induced by 0.1 g small microplastics (d < 0.5 mm) was 0.55 and 0.79 at pH 6.0 and 8.0, respectively.
Key words: microplastics      iron salt      ultrafiltration      shortened membrane process      membrane fouling     

塑料及其制品在工业、农业以及日常生活中被广泛使用, 自20世纪40年代开始大规模生产以来, 塑料的产量迅速增加.从20世纪50年代的1.5×106 t ·a-1大幅增加到2011年的2.8×108 t, 据估计目前全球每年产生的塑料产品超过3×108 t, 进入海洋的塑料垃圾至少8×106 t[1~3].残存在环境中的塑料具有化学性质稳定、密度低、粒径小等特点, 但在长期的太阳辐射、风力、海浪等物理或化学作用下会分解成塑料碎片或者颗粒, 当其粒径小于5 mm时被称为“微塑料”[4~6].

微塑料体积小、比表面积大和难降解, 容易吸附环境中的重金属、持久性有机污染物, 如农药、阻燃剂和多氯联苯等[7~11].微塑料作为载体, 可携带外来物种及潜在病原菌[12, 13], 破坏生态环境, 危害生物体健康.还可以由地表径流在海洋中蔓延, 改变海洋的生态环境, 进入海洋生物食物链, 对海洋生物造成危害, 并且随着食物链的传递作用, 微塑料最终进入人类的食物链, 造成更严重的危害[14~16].

前期的研究表明, 微塑料普遍存在于表层海水、河口以及沉积物中, 在极地冰川和河流湖泊沉积物中也有发现[17~22].近年来, 在淡水水源(河流、湖泊和水库等)也检测到了微塑料.据报道, 长江口微塑料平均丰度为(4.1×103±2.5×103) items ·m-3[23], 三峡大坝附近地表水微塑料丰度为1.6×103~1.23×104 items ·m-3[24].太湖的表层水体中也报道了微塑料的赋存, 丰度甚至达到3.4×106~25.8×106 items ·m-3[25].水体中已检测到的微塑料虽然种类繁多, 如聚乙烯(PE)、聚丙烯(PP)、聚氯乙烯(PVC)和聚苯乙烯等, 但PE的检出比例远高于其他种类[26].

截至目前, 混凝-膜滤工艺在饮用水处理工艺中已得到广泛应用[27~29].短流程膜工艺以其除污效能高、占地面积小等优点成为近年来重要的研究方向.随着微塑料在饮用水源地的逐渐检出, 了解微塑料对短流程膜工艺的运行效能影响显得至关重要.因此, 本文以水环境中丰度较高的聚乙烯为目标污染物, 考察了短流程膜工艺中, 微塑料对超滤膜污染的影响机制.

1 材料与方法 1.1 实验材料

本实验所用试剂, 如FeCl3 ·6H2O、NaHCO3、HCl和NaOH均为分析纯, 购自国药集团化学试剂有限公司(北京).实验所用微塑料取自聚乙烯泡沫板, 经砂纸细磨后, 用分样筛将聚乙烯塑料分为不同粒径(2 < d1 < 5 mm、1 < d2 < 2 mm、0.5 < d3 < 1 mm和d4 < 0.5 mm).超滤杯(Amicon 8400)购自Millipore公司(美国).平板超滤膜(100×103)购自安德膜科技有限公司(北京), 材质为聚偏氟乙烯(PVDF).

1.2 实验装置与方法

本实验装置如图 1所示.向超滤杯内注入300 mL去离子水, 随后加入一定量的NaOH或HCl (0.01 mol ·L-1), 为使体系中pH混凝后稳定在6.0、7.0和8.0, 加入3 mL NaHCO3(0.1 mol ·L-1)作为缓冲溶液.之后, 加入0.1 g微塑料.快转(350 r ·min-1)1 min, 慢转(100 r ·min-1)14 min, 进行膜过滤.采用10 mg ·L-1氯化钠作为背景离子强度.本实验过程中用膜比通量J/J0代表膜污染状况, 其中J0为初始膜通量.膜比通量越大, 表示膜污染程度越轻.所有实验至少两次平行.

图 1 实验装置示意 Fig. 1 Schematic diagram of the experimental set up

1.3 分析方法

pH通过Orion pH Benchtop测定; 膜通量通过数字记录仪(HCB1002, Denver, USA)自动存储; 膜表面形貌通过扫描电子显微镜(JEOL Ltd, Tokyo, Japan)和相机((Nikon, Coolpix P7100, Japan)测定, 相机拍摄时, 由于所用微塑料和超滤膜均为白色, 拍摄前用亚甲基蓝将微塑料染色2 h(除加0.9 mmol ·L-1氯化铁时); 絮体粒径通过Mastersizer 2000激光粒度仪测定(Malvern, UK); Zeta电位通过Delsa Nano C(Beckman Coulter, USA)测定.

2 结果与讨论 2.1 微塑料引起的膜污染

首先考察了pH 7.0时0.1 g不同粒径微塑料的膜污染行为.由图 2(a)所示, 微塑料粒径越小, 膜比通量越低, 膜污染程度越严重.微塑料粒径分别为2 < d1 < 5 mm、1 < d2 < 2 mm、0.5 < d3 < 1 mm和d4 < 0.5 mm时, 膜比通量依次降低为0.87、0.85、0.84和0.83(选取前600 s膜比通量变化, 下同).由于所用超滤膜的平均孔径为(47.9±6.4) nm, 微塑料本身并不会吸附或者堵塞超滤膜孔, 此时引起超滤膜污染的主要方式是微塑料形成的滤饼层.微塑料粒径越小, 在超滤膜表面形成的滤饼层相对致密, 膜污染越严重, 但膜污染加剧的趋势不明显.

(a)单独微塑料; (b)微塑料混凝后; (c)不同粒径比例微塑料混合物混凝后 图 2 pH 7.0时不同粒径微塑料混凝前后引起的膜污染 Fig. 2 Membrane fouling caused by microplastics with different particle sizes before and after coagulating at pH 7.0

进一步考察了铁盐与不同粒径微塑料混凝后导致的膜污染.由图 2(b)可知, 单独铁盐(0.3 mmol ·L-1)时, 松散的水解絮体引起的膜污染程度较轻, 膜比通量为0.81.而铁盐与微塑料混凝后, 滤饼层厚度增加, 膜污染加剧, 尤其小粒径微塑料.此时膜比通量分别为0.74(d1)、0.71(d2)、0.62(d3)和0.48(d4), 膜污染加剧程度远高于无混凝剂时[图 2(a)].

为进一步验证小粒径微塑料能严重加剧膜污染, 考察了不同粒径微塑料(2 < d1 < 5 mm、d4 < 0.5 mm)以不同比例混合后膜污染程度.如图 2(c)所示, 粒径2~5 mm的微塑料与氯化铁絮体混凝后导致的膜比通量为0.68.然而, 在保持投加总量一致的情况下, 随着小粒径微塑料比例的增大, 膜污染程度严重加剧, 此时膜比通量逐渐降低为0.65(d1 :d4=3 :1)、0.61(d1 :d4=1 :1)、0.53(d1 :d4=1 :3)和0.43(d4 < 0.5 mm).

2.2 铁盐浓度的影响

一方面, 膜污染随微塑料粒径减小而加剧.另一方面, 混凝剂投量随水质不同而改变[30~32].进一步研究了小粒径微塑料(d4 < 0.5 mm)与不同浓度铁盐混凝后导致的膜污染.首先考察了混凝剂本身对膜污染的影响.结果表明, 膜比通量随铁盐投量的增加而逐渐降低.当混凝剂浓度分别为0.1、0.3、0.6和0.9 mmol ·L-1时, 膜比通量为0.82、0.81、0.77和0.76[图 3(a)].仅0.1 mmol ·L-1铁盐时, 膜污染程度最轻[图 4(a)].尽管膜污染程度随混凝剂投量增加而加剧, 但混凝剂水解絮体松散, 膜污染加剧程度也不明显, 运行结束后膜比通量仅变化0.06.

图 3 pH 7.0时微塑料混凝前后膜比通量 Fig. 3 Membrane specific flux caused by microplastics before and after coagulation at pH 7.0

(a) 0.1 mmol ·L-1氯化铁; (b) 0.1 mmol ·L-1氯化铁与0.1 g微塑料(d4 < 0.5 mm)混凝; (c) 0.9 mmol ·L-1氯化铁与0.1 g微塑料(d4 < 0.5 mm)混凝 图 4 pH 7.0时微塑料混凝前后超滤膜表面形貌 Fig. 4 Surface morphology of membrane caused by microplastics before and after coagulation at pH 7.0

而与小粒径微塑料(d4 < 0.5 mm)混凝后, 膜污染程度明显加剧, 此时, 膜比通量分别降低为0.76、0.74、0.70和0.62[图 3(b)].从图 4中可以看出, 混凝后絮体与微塑料相对均匀地分布在超滤膜表面[图 4(b)和4(c)], 滤饼层更致密, 因而膜污染程度更严重.随着铁盐浓度的增加, 滤饼层厚且致密, 膜污染程度进一步加剧, 运行结束后膜比通量变化0.14.

2.3 pH的影响

絮体的性质受pH影响较大[33], 进一步研究了不同pH条件下微塑料对膜污染程度的影响.从图 5可以看出, 膜污染程度随pH升高而降低. pH为6.0、7.0和8.0时, 单独0.3 mmol ·L-1氯化铁水解絮体造成的膜比通量分别为0.70、0.76和0.81.与小粒径微塑料(d4 < 0.5 mm)混凝后, 膜污染程度加剧, 尤其酸性条件下, 相应膜比通量分别为0.55、0.69和0.79.

图 5 不同pH条件下0.3 mmol ·L-1氯化铁与微塑料混凝后引起的膜污染 Fig. 5 Membrane fouling caused by microplastics after coagulating with 0.3 mmol ·L-1 FeCl3 ·6H2O under different pH conditions

进一步研究表明, 膜污染程度随pH降低而加剧归于以下原因：①pH 6.0、7.0和8.0时, 0.3 mmol ·L-1氯化铁水解絮体的表面电荷大部分呈正电, 分别为(10.16±2.81)、(3.96±0.84)和(-23.68±0.69) mV, 而此时微塑料的表面电位呈负电, 分别为(-6.98±1.11)、(-13.32±6.89)和(-15.05±4.66) mV[图 6(a)], 低pH时微塑料更易被絮体吸附; ②氯化铁水解絮体平均粒径(d50)随pH增加而增大[图 6(b)], pH 6.0、7.0和8.0的平均粒径分别为413 μm、622 μm和694 μm.低pH时絮体粒径小, 在超滤膜表面形成的滤饼层更致密[图 6(c)和6(d)], 加剧膜污染.

(a)氯化铁水解絮体和微塑料Zeta电位; (b)氯化铁水解絮体粒径变化; (c)和(d) pH 6.0和pH 8.0絮体在超滤膜表面形貌 图 6 不同pH时絮体性质及膜表面形貌 Fig. 6 Properties of flocs and surface morphology of membranes at different pH value

2.4 微塑料混凝前后膜污染机制及环境意义

综上所述, 微塑料单独存在时, 由于其粒径远大于膜孔, 膜污染程度较轻.在短流程膜工艺中, 微塑料与铁盐混凝后直接进入膜池, 且相对均匀地分散在膜表面.随着铁盐投量增加, 滤饼层厚度相应增加, 此时小粒径微塑料可能进入絮体内部网络空间, 滤饼层更致密, 进一步加剧膜污染.与碱性环境相比, 酸性环境时, 铁盐絮体表面带正电荷且粒径较小, 更容易吸附/捕获水环境中呈负电性的微塑料, 在膜表面形成的滤饼层也更致密, 膜污染程度严重.微塑料混凝前后引起膜污染的机制示意图见图 7.

图 7 微塑料混凝前后超滤膜污染机制示意 Fig. 7 Schematic diagram of UF membrane fouling mechanisms induced by microplastics before and after coagulation

以上研究表明, 小粒径微塑料能急剧加剧膜污染.理论上讲, 低压滤膜(微滤和超滤)由于孔径小, 可将混凝前后微塑料全部截留, 所形成的滤饼层相对松散, 且绝大部分为可逆污染.然而, 受机械、光解和微生物等作用, 微塑料会进一步分解成纳米尺度塑料.随着微纳塑料在环境中的检出, 其对水质尤其膜污染的影响更严重.在实际水环境中, 微纳塑料本身是污染物, 更重要的是, 微纳塑料可作为优良载体, 不仅能有效吸附重金属、持久性有机污染物等有毒物质, 也容易滋养、携带病原菌等微生物, 成为严重的污染源.微纳塑料作为一种新型污染物, 当前的研究多以检测方法、吸附效能和毒理学效应等为主, 后续应多关注微纳塑料作为载体滋养微生物对膜污染的影响, 尤其纳塑料.

3 结论

(1) 微塑料对超滤膜污染程度影响较低, 但小粒径微塑料, 尤其混凝后形成致密的滤饼层能显著加剧膜污染.

(2) 超滤膜污染程度随混凝剂投量增大而加剧.混凝过程中, 大粒径微塑料往往被拦截于絮体表面, 而小粒径微塑料容易进入絮体形成的内部网络, 形成致密滤饼层, 加剧膜污染.

(3) 水体中微塑料多呈负电, 酸性条件下氯化铁水解絮体粒径较小且带正电荷, 易吸附微塑料形成致密滤饼层, 引起严重的膜污染.

参考文献
[1] Plastics Europe. Plastics-The Facts 2012: an analysis of European plastics production, demand and waste data for 2011[R]. Brussels: Association of Plastic Manufacturers, 2012, 38.
[2] 许旺, 梁鸿, 马嵩, 等. 我国海岸带系统微塑料污染危害及治理对策[J]. 环境与可持续发展, 2018, 43(2): 21-26.
Xu W, Liang H, Ma S, et al. Microplastics pollution and manage countermeasures in the coastal environment of China[J]. Environment and Sustainable Development, 2018, 43(2): 21-26. DOI:10.3969/j.issn.1673-288X.2018.02.005
[3] 柴勇, 王寒冰, 张钰, 等. 致命的海洋垃圾[J]. 人与自然, 2017(11): 10-25.
[4] 王昆, 林坤德, 袁东星. 环境样品中微塑料的分析方法研究进展[J]. 环境化学, 2017, 36(1): 27-36.
Wang K, Lin K D, Yuan D X. Research progress on the analysis of microplastics in the environment[J]. Environmental Chemistry, 2017, 36(1): 27-36.
[5] Wagner M, Scherer C, Alvarez-Muñoz D, et al. Microplastics in freshwater ecosystems:what we know and what we need to know[J]. Environmental Sciences Europe, 2014, 26(1): 12. DOI:10.1186/s12302-014-0012-7
[6] 徐擎擎, 张哿, 邹亚丹, 等. 微塑料与有机污染物的相互作用研究进展[J]. 生态毒理学报, 2018, 13(1): 40-49.
Xu Q Q, Zhang G, Zou Y D, et al. Interactions between microplastics and organic pollutants:current status and knowledge gaps[J]. Asian Journal of Ecotoxicology, 2018, 13(1): 40-49.
[7] Eriksen M, Liboiron M, Kiessling T, et al. Microplastic sampling with the AVANI trawl compared to two neuston trawls in the bay of Bengal and South Pacific[J]. Environmental Pollution, 2018, 232: 430-439. DOI:10.1016/j.envpol.2017.09.058
[8] Li H X, Getzinger G J, Ferguson P L, et al. Effects of toxic leachate from commercial plastics on larval survival and settlement of the barnacle Amphibalanus amphitrite[J]. Environmental Science & Technology, 2016, 50(2): 924-931.
[9] Hermabessiere L, Dehaut A, Paul-Pont I, et al. Occurrence and effects of plastic additives on marine environments and organisms:a review[J]. Chemosphere, 2017, 182: 781-793. DOI:10.1016/j.chemosphere.2017.05.096
[10] Kolandhasamy P, Su L, Li J N, et al. Adherence of microplastics to soft tissue of mussels:a novel way to uptake microplastics beyond ingestion[J]. Science of the Total Environment, 2018, 610-611: 635-640. DOI:10.1016/j.scitotenv.2017.08.053
[11] Ma B W, Xue W J, Hu C Z, et al. Characteristics of microplastic removal via coagulation and ultrafiltration during drinking water treatment[J]. Chemical Engineering Journal, 2019, 359: 159-167. DOI:10.1016/j.cej.2018.11.155
[12] Brennecke D, Duarte B, Paiva F, et al. Microplastics as vector for heavy metal contamination from the marine environment[J]. Estuarine, Coastal and Shelf Science, 2016, 178: 189-195. DOI:10.1016/j.ecss.2015.12.003
[13] Foulon V, Le Roux F, Lambert C, et al. Colonization of polystyrene microparticles by Vibrio crassostreae:light and electron microscopic investigation[J]. Environmental Science & Technology, 2016, 50(20): 10988-10996.
[14] Farrell P, Nelson K. Trophic level transfer of microplastic:Mytilus edulis (L.) to Carcinus maenas (L.)[J]. Environmental Pollution, 2013, 177: 1-3. DOI:10.1016/j.envpol.2013.01.046
[15] Pellini G, Gomiero A, Fortibuoni T, et al. Characterization of microplastic litter in the gastrointestinal tract of Solea solea from the Adriatic Sea[J]. Environmental Pollution, 2018, 234: 943-952. DOI:10.1016/j.envpol.2017.12.038
[16] 邹亚丹, 徐擎擎, 张哿, 等. 6种消解方法对荧光测定生物体内聚苯乙烯微塑料的影响[J]. 环境科学, 2019, 40(1): 496-503.
Zou Y D, Xu Q Q, Zhang G, et al. Influence of six digestion methods on the determination of polystyrene microplastics in organisms using the fluorescence intensity[J]. Environmental Science, 2019, 40(1): 496-503.
[17] Fischer V, Elsner N O, Brenke N, et al. Plastic pollution of the Kuril-Kamchatka Trench area (NW pacific)[J]. Deep Sea Research Part Ⅱ:Topical Studies in Oceanography, 2015, 111: 399-405. DOI:10.1016/j.dsr2.2014.08.012
[18] Bergmann M, Wirzberger V, Krumpen T, et al. High quantities of microplastic in Arctic deep-sea sediments from the HAUSGARTEN observatory[J]. Environmental Science & Technology, 2017, 51(19): 11000-11010.
[19] Peng G Y, Zhu B S, Yang D Q, et al. Microplastics in sediments of the Changjiang estuary, China[J]. Environmental Pollution, 2017, 225: 283-290. DOI:10.1016/j.envpol.2016.12.064
[20] Zhang W W, Zhang S F, Wang J Y, et al. Microplastic pollution in the surface waters of the Bohai Sea, China[J]. Environmental Pollution, 2017, 231: 541-548. DOI:10.1016/j.envpol.2017.08.058
[21] 简敏菲, 周隆胤, 余厚平, 等. 鄱阳湖-饶河入湖段湿地底泥中微塑料的分离及其表面形貌特征[J]. 环境科学学报, 2018, 38(2): 579-586.
Jian M F, Zhou L Y, Yu H P, et al. Separation and microscopic study of microplastics from the sediments of the wetland in the estuary of Raohe River of Poyang Lake[J]. Acta Scientiae Circumstantiae, 2018, 38(2): 579-586.
[22] 朱晓桐, 衣俊, 强丽媛, 等. 长江口潮滩表层沉积物中微塑料的分布及沉降特点[J]. 环境科学, 2018, 39(5): 2067-2074.
Zhu X T, Yi J, Qiang L Y, et al. Distribution and settlement of microplastics in the surface sediment of Yangtze Estuary[J]. Environmental Science, 2018, 39(5): 2067-2074.
[23] Zhao S Y, Zhu L X, Wang T, et al. Suspended microplastics in the surface water of the Yangtze Estuary System, China:first observations on occurrence, distribution[J]. Marine Pollution Bulletin, 2014, 86(1-2): 562-568. DOI:10.1016/j.marpolbul.2014.06.032
[24] Di M X, Wang J. Microplastics in surface waters and sediments of the Three Gorges Reservoir, China[J]. Science of the Total Environment, 2018, 616-617: 1620-1627. DOI:10.1016/j.scitotenv.2017.10.150
[25] Su L, Xue Y G, Li L G, et al. Microplastics in Taihu Lake, China[J]. Environmental Pollution, 2016, 216: 711-719. DOI:10.1016/j.envpol.2016.06.036
[26] Andrady A L. Microplastics in the marine environment[J]. Marine Pollution Bulletin, 2011, 62(8): 1596-1605. DOI:10.1016/j.marpolbul.2011.05.030
[27] 王雨菲.基于"后絮凝"控制的混凝-膜过滤饮用水处理技术研究[D].天津: 天津大学, 2017.
Wang Y F. Study of coagulation-Membrane filtration technology for drinking water treatment based on re-flocculation control[D]. Tianjin: Tianjin University, 2017.
[28] 李满屯, 贾瑞宝, 于衍真, 等. 超滤膜工艺技术在饮用水处理的应用研究进展[J]. 净水技术, 2012, 31(6): 18-21.
Li M T, Jia R B, Yu Y Z, et al. Advances in application research of technological processes of ultrafiltration membrane in drinking water treatment[J]. Water Purification Technology, 2012, 31(6): 18-21. DOI:10.3969/j.issn.1009-0177.2012.06.005
[29] 付宛宜, 张锡辉, 叶挺进, 等. 超滤膜及其组合工艺在饮用水处理中的应用[J]. 中国给水排水, 2013, 29(22): 1-6.
Fu W Y, Zhang X H, Ye T J, et al. Application of ultrafiltration and its combined process in drinking water treatment[J]. China Water & Wastewater, 2013, 29(22): 1-6.
[30] Sillanpää M, Ncibi M C, Matilainen A, et al. Removal of natural organic matter in drinking water treatment by coagulation:a comprehensive review[J]. Chemosphere, 2017, 190: 54-71.
[31] Duan J M, Gregory J. Coagulation by hydrolysing metal salts[J]. Advances in Colloid and Interface Science, 2003, 100-102: 475-502. DOI:10.1016/S0001-8686(02)00067-2
[32] 潘世英, 万吉昌, 高宝玉, 等. 混凝实验条件下混凝剂最佳投加量的选择方法研究[J]. 工业水处理, 2011, 31(10): 25-27.
Pan S Y, Wan J C, Gao B Y, et al. Studies on the determination of optimum dosage of coagulant under different coagulation experimental conditions[J]. Industrial Water Treatment, 2011, 31(10): 25-27.
[33] 马百文.絮体与超滤膜协同作用下的净水效能与机制[D].北京: 中国科学院大学, 2015.
Ma B W. Ultrafiltration membrane purification efficiency and mechanism with the synergistic effect of flocs[D]. Beijing: University of Chinese Academy of Sciences, 2015.