Wastewater disposal plants are considered as the main discharge and storage sites for microplastics.In order to explore the differences in the removal efficiency of microplastics from sewage in different disposal stages of urban wastewater disposal plants,a sewage disposal plant in Inner Mongolia was taken as the research object.Through adopting a stereomicroscope for observation and with the help of statistical analysis by using LAS X software,the results showed that:the main form of microplastics in sewage plants is fibrous(61.8％),followed by fragmented and thin film forms.The size of microplastics mainly concentrates in the range of 0.25～0.50mm.The structures with the best removal efficiency for microplastics in the primary disposal process are coarse grid,fine grid,and initial sedimentation tank,especially for microplastic particles smaller than 0.25mm.The cyclone sedimentation tank does not have a positive removal effect on fibers,fragments,and thin film microplastics.The secondary sedimentation tank in the secondary disposal process played a key role in the removal of microplastics,followed by the fiber biological rotary table,which has the highest removal efficiency for microplastics with sizes ranging from 0.50 to 1.00mm The removal efficiency of three types of microplastics in the first level disposal process was positive,and the removal efficiency was negatively correlated with the size of microplastics.The removal efficiency of structures in the first level disposal process is relatively stable for small-sized microplastics,while the removal efficiency of large-sized microplastics fluctuated greatly.The removal efficiency of microplastics with different shapes decreased along the flow direction of sewage in each disposal process.The removal efficiency of three types of microplastics in the second level disposal process is negative,while only for microplastics with a size less than 0.50mm is positive.This study aims to provide theoretical guidance for the operation and management of sewage disposal plants to improve the removal efficiency of microplastics.
维普
万方数据