Investigation and numerical modelling of microplastics in clean water treatment systems and a systematic review of the health effects of microplastics

微塑料（MP）污染的话题在全球范围内引起了相当大的兴趣，人们担心它们对人类健康和环境的潜在危害。MP可以被定义为小于5 mm的小塑料片。随着时间的推移，MP在自然环境中积累。许多研究都集中在海洋环境中MP的存在以及对鱼类和其他海洋生物的有害影响。最近的研究开始关注废水处理厂以及自来水和瓶装水中的MP，最近发表的一项关于自来水的国际研究表明，83%的自来水样本被发现受到MP污染（The Lancet Planetary Health，2017）。饮用水处理厂（DWTPs）中MP的数量是一个研究不足的领域，只有少数研究试图量化进水和出水中的MP。MP通过DWTP的运动是一个新的感兴趣的领域，没有发现文献报道了MP在许多治疗阶段的浓度。因此，没有真实的了解各个治疗阶段对MP清除的成功率。清洁水中聚合物的主要来源也远未被理解，MP对人类健康的潜在影响也是未知的。必须获得这些信息，以了解从清洁水系统中清除MP的紧迫性。主要研究目的是：- 制定供水系统内MP采样和分析规程;量化整个系统中存在的MP数量并确定此类聚合物的潜在来源;确定与饮用水中MP存在相关的主要风险，以更好地了解去除MP的必要性。这项研究与EPSRC的“水工程”研究领域保持一致。“该项目的第一阶段是开发一种合理的采样和测试方法，用于定量和识别清洁水系统中的MP。必须仔细设计采样方法，考虑天气条件、采样深度、样本大小和数量的代表性、潜在污染等的潜在影响。然后设计检测方法，仅从样本中分离MP。最后，将采用聚合物的鉴定和表征方法。第二阶段将执行第一阶段创建的方法，并在NI Water拥有的三个单独污水处理厂的各个阶段采集样本。将进一步比较每个处理厂提供的家庭自来水和瓶装水。处理厂的来源将有所不同（河流、湖泊和高地来源），以便与我进行比较，了解不同的提取来源对MP数量的影响。取样后，将对每个样本进行实验室分析，以便对MP数量进行量化。将对发现的聚合物进行鉴定和表征，提供重要信息以帮助理解两者;发现的MP的来源以及DWTP对不同聚合物类型和形状的去除效率。统计分析将审查MP数量和处理阶段、MP类型/数量和水源等之间关系的重要性。前两个阶段的结果将有助于更详细地告知本项目的后续步骤。通过污水处理厂的颗粒流的建模和从清洁水系统中提取MP的方法的设计预计将是重要的下一步。据认为，由于聚合物的疏水性质，粘附在MP颗粒上的生物膜和其他污染物可能对人类健康构成重大风险。将对收集到的MP进行评估，以更好地了解潜在风险。

The topic of microplastic (MP) pollution has been gaining considerable interest globally, with concern of their potential harm towards human health and the environment. MPs can be defined as small pieces of plastic which are <5mm. Over time, MPs accumulate within the natural environment. Much research has focused on the presence of MPs within the marine environment and the harmful effects on fish and other marine life. More recent research has begun to focus on MPs within wastewater treatment plants and tap and bottled water, with a recently published international study of tap water stating that 83% of tap water samples were found to be contaminated with MPs (The Lancet Planetary Health, 2017). The quantity of MPs within drinking water treatment plants (DWTPs) is an area which is under-researched, with only a few studies attempting to quantify MPs in influent and effluent water. The movement of MPs through DWTPs is a novel area of interest, with no literature found which has reported on MP concentrations at numerous treatment stages. Therefore, there is no real understanding of the success rates of the individual treatment stages on MP removal. The main sources of polymers in clean water is also far from being understood and the potential impacts of MPs on human health are unknown. This information must be acquired to understand the urgency of developments to be made for the removal of MPs from the clean water system. The main study aims are; - to develop a protocol for the sampling and analysis of MPs within the water supply system; to quantify the amount of MP present throughout the system and identify the potential sources of such polymers; to identify the main risks associated with MP presence in drinking water to gain a greater understanding of the need for MP removal. This study is aligned to EPSRC's research area of 'water engineering.' The first stage of this project is to develop a sound sampling and testing methodology for the quantification and identification of MPs in clean water systems. The sampling methodology must be carefully designed, accounting for the potential effects of weather conditions, sampling depth, representativeness of sample size and numbers, potential contamination etc. Testing methodology will then be designed to isolate only the MPs from the sample. Finally, methods for the identification and characterisation of polymers will be adapted. Stage two will be to carry out the methodology created in stage one, with samples taken at various stages of three individual DWTPs owned by NI Water. Further comparisons will be made to tap water from households provided by each treatment plant and bottled water. The sources of the treatment plants will differ (a river, lough and an upland source), for comparisons to me made relating to differing abstraction sources on MP quantities found. Following sampling, each sample will be subjected to laboratory analysis, allowing for the quantification of MP numbers. The identification and characterisation of polymers found will be undertaken, providing important information to aid understanding of both; the sources of the MPs found, and the removal efficiency of the DWTP on different polymer types and shapes. Statistical analysis will review the significance of relationships between; MP number and treatment stage, MP types/quantities found and water sources etc. The results found from the first two phases will help to inform the next steps of this project in more detail. Modelling of particle flow through the DWTP and design of an extraction method of MPs from the clean water system are expected to be important next steps. It is thought that biofilms and other contaminants, which adhere to MP particles due to the hydrophobic nature of polymers, may pose a significant risk to human health. The MPs collected will be assessed to try to gain a greater understanding of potential risks.