Microplastic abundance, characteristics, and removal in wastewater treatment plants in a coastal city of China

• Published in: Water research (Oxford) Vol. 155; pp. 255 - 265
• Main Authors: Long, Zouxia, Pan, Zhong, Wang, Wenling, Ren, Jianye, Yu, Xingguang, Lin, Liangyu, Lin, Hui, Chen, Hongzhe, Jin, Xianglong
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.05.2019
• Subjects: Abundance; Characteristics; Microplastic; Removal; Wastewater treatment plant; Removal; Abundance; Wastewater treatment plant; Microplastic; Characteristics
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2019.02.028

Studying the abundance, characteristics, and removal of microplastics (MPs) in wastewater treatment plants (WWTPs) in coastal cities is of great significance for understanding the impacts of human activities on the marine environment, but currently, little information on this topic is available in China. Therefore, the abundance, characteristics, and removal of MPs in seven WWTPs of Xiamen, a typical coastal city in China, are studied. Sixty samples were collected using an improved sampling method involving an electromagnetic flowmeter and a fast digital camera. The influent MPs concentration is 1.57–13.69 items/L, and it is reduced to 0.20–1.73 items/L in the effluent, indicating that 79.3–97.8% MPs is removed. Based on the daily effluent discharge and MPs removal rate, it is estimated that ∼6.5 × 108 MPs are released from the seven WWTPs into the Xiamen Bay each day. The light microscopic and micro-Raman spectroscopic analysis indicates that ∼62.68% of particles are plastic polymers, including polypropylene (31.6%), polyethylene (21.9%), polystyrene (10.1%), propylene/ethylene copolymer (9.2%), and polyethylene terephthalate (7.5%). The color of MPs is mainly composed of white (27.3%) and clears (25.8%). Our results show that granules (41.1%) are the dominant shape of MPs, followed by fragments (31.3%), fibers (23.7%), and pellet (3.9%). The characteristics of MPs such as sizes, shapes, and types affect the MPs removal in WWTPs. Our findings show that MPs concentration in the influent is positively correlated with the suspended solids (SS), however, in the effluent, it is associated with the WWTPs operating load, as reflected by obviously higher MP abundance in overloaded ones. [Display omitted] •Microplastics (MPs) in wastewater treatment plants (WWTPs) in a coastal city of China is investigated.•The sampling is improved by the combined use of an electromagnetic flowmeter and a digital camera.•The MPs abundance, characteristics, and removal in both influents and effluents are studied.•MPs concentration in the influent is positively correlated with the suspended solids.•The size, shape and type of MPs affect its removal rate in WWTPs.