Abstract：
This review discusses the micro-nano plastics (MNPs) and their interaction with physical, chemical and biological processes in a constructed wetland (CW) system that is typically used as a nature-based tertiary wastewater treatment for municipal as well as industrial applications. Individual components of the CW system such as substrate, microorganisms and plants were considered to assess how MNPs influence the CW processes. One of the main functions of a CW system is removal of nutrients like nitrogen (N) and phosphorus (P) and here we highlight the pathways through which the MNPs influence CW\'s efficacy of nutrient removal. The presence of morphologically (size and shape) and chemically different MNPs influence the growth rate of microorganisms important in N and P cycling, invertebrates, decomposers, and the plants which affect the overall efficiency of a CW treatment system. Certain plant species take up the MNPs, and some toxicity has been observed. This review focuses on two significant aspects: (1) the presence of MNPs in a significant concentration affects the efficiency of N and P removal, and (2) the removal of MNPs. Because MNPs reduce the enzyme activities in abundance and overproduction of ROS oxidizes the enzyme active sites, resulting in the depletion of proteins, ultimately inhibiting nitrogen and phosphorus removal within the substrate layer. The review found that the majority of the studies used sand-activated carbon (SAC), granular-activated carbon (GAC), rice straw, granular limestone, and calcium carbonate, as a substrate for CW treatment systems. Common plant species used in the CW include Phragmites, Arabidopsis thaliana, Lepidium sativum, Thalia dealbata, and Canna indica, which were also found to be dominant in the uptake of the MNPs in the CWs. The MNPs were found to affect earthworms such as Eisenia fetida, Caenorhabditis elegans, and, Enchytraeus crypticus, whereas Metaphire vulgaris were found unaffected. Though various mechanisms take place during the removal process, adsorption and uptake mechanism effectively emphasize the removal of MNPs and nitrogen and phosphorus in CW. The MNPs characteristics (type, size, and concentration) play a crucial role in the removal efficiency of nano-plastics (NPs) and micro-plastics (MPs). The enhanced removal efficiency of NPs compared to MPs can be attributed to their smaller size, resulting in a faster reaction rate. However, NPs dose variation showed fluctuating removal efficiency, whereas MPs dose increment reduces removal efficiency. MP and NPs dose variation also affected toxicity to plants and earthworms as observed from data. Understanding the fate and removal of microplastics in wetland systems will help determine the reuse potential of wastewater and restrict the release of microplastics. This study provides information on various aspects and highlights future gaps and needs for MNP fate study in CW systems.
摘要：
这篇综述讨论了微纳米塑料(MNPs)及其与物理,人工湿地（CW）系统中的化学和生物过程，通常用作市政和工业应用的基于自然的三级废水处理。CW系统的各个组件，例如基板，微生物和植物被认为是评估MNPs如何影响CW过程。CW系统的主要功能之一是去除氮（N）和磷（P）等养分，在此我们重点介绍了MNPs影响CW养分去除功效的途径。形态（大小和形状）和化学上不同的MNPs的存在影响在N和P循环中重要的微生物的生长速率，无脊椎动物,分解者，以及影响CW处理系统整体效率的植物。某些植物物种占据了MNPs，并观察到一些毒性。本文的综述主要集中在两个重要方面：（1）MNPs的存在浓度显着影响N和P的去除效率，和(2)MNPs的去除。因为MNPs降低了酶的丰度和过量生产的ROS氧化酶的活性位点，导致蛋白质的消耗，最终抑制衬底层内氮和磷的去除。审查发现，大多数研究使用砂活性炭(SAC)，颗粒活性炭(GAC)，稻草,粒状石灰石,和碳酸钙，作为CW处理系统的基底。CW中使用的常见植物种类包括芦苇，拟南芥，Lepidiumsativum,Thaliadealbata,还有Cannaindica,也被发现在CW中MNPs的摄取中占主导地位。这些MNPs被发现会影响蚯蚓，比如费蒂达爱胜因，秀丽隐杆线虫,and,隐秘的附魔,而普通Metaphire被发现未受影响。尽管在去除过程中会发生各种机制，吸附和吸收机制有效地强调了CW中MNPs和氮磷的去除。MNPs特征(类型，尺寸,和浓度）在纳米塑料（NPs）和微塑料（MPs）的去除效率中起着至关重要的作用。与MP相比，NPs的去除效率提高可以归因于它们较小的尺寸，导致更快的反应速率。然而,NPs剂量变化显示去除效率波动，而MPs剂量增加降低了去除效率。从数据中观察到，MP和NP的剂量变化也会影响对植物和蚯蚓的毒性。了解湿地系统中微塑料的命运和去除将有助于确定废水的再利用潜力，并限制微塑料的释放。这项研究提供了有关各个方面的信息，并强调了CW系统中MNP命运研究的未来差距和需求。
