Impact of microplastics on organic fouling of hollow fiber membranes

Given the potential hazards of microplastics (MPs), it is desirable to efficiently remove them during wastewater treatment processes. To this end, ultrafiltration (UF) membranes can significantly increase the removal of MPs, however the fouling of such membrane modules can also be impacted by the presence of MPs. Magnetic Reso-nance Imaging (MRI) was used here to non-invasively quantify the effect of polyethylene (PE) MPs accumulation in a 3D UF hollow fiber (HF) membrane module containing 400 fibers, via direct non-invasive velocity imaging of the flow distribution between individual fibers during module operation. The co-effect of MPs and alginate (a common organic model foulant mimicking extracellular polymeric substances (EPS)) on fouling of the HF module was then explored. Flow was initially equally distributed with fouling causing flow in particular fibers to be significantly reduced. Fouling with MPs resulted in minimal flow distribution disruption and was easily remediated hydraulically, in contrast alginate fouling required chemical cleaning in order to fully restore ho-mogeneous flow distribution between the fibers. The presence of both MPs and alginate resulted in a more heterogeneous disruption of the fibre flow distribution due to fouling and resulted in much more effective hy-draulic cleaning of the module.

Automated summary

In order to efficiently remove microplastics (MPs) during wastewater treatment processes, ultrafiltration (UF) membranes can be used to increase the removal of MPs. However, the fouling of these membranes can also be affected by the presence of MPs. Magnetic Resonance Imaging (MRI) was used to measure the accumulation of polyethylene (PE) MPs in a 3D UF hollow fiber (HF) membrane module and investigate their impact on fouling. The study found that MPs fouling can be easily remedied by hydraulic cleaning, while alginate fouling requires chemical cleaning for complete restoration of flow distribution. The presence of both MPs and alginate resulted in a more heterogeneous disruption of flow distribution and more effective hydraulic cleaning.