Behavior and removal of microplastics during desalination in a lab-scale direct contact membrane distillation system

The behavior of microplastic particles (MPPs) is explored in a lab-scale direct contact membrane distillation (DCMD) system used to produce drinking water from seawater, while also analyzing the impact of their presence on the process performance. Commercial MPPs (LDPE, PET and uPVC) were first studied by temperature stress (TS) tests (using amber bottles) to mimic the exposure to the high temperatures commonly used in DCMD (ca. 80 degrees C), which led to uPVC being selected to be tested under different loads and aging degrees in the DCMD system. By analyzing uPVC MPPs samples before and after the TS and DCMD experiments by ATR-FTIR, UV-Visible spectroscopy and SEM, it was concluded that minor aging is expected to occur. High loads (>0.1 g L-1) of uPVC MPPs decreased the DCMD performance in terms of permeate flux (from 32.8 & PLUSMN; 0.3 with filtered seawater to 28.7 & PLUSMN; 0.3 kg m- 2 h-1 with a load of 0.2 g L-1), although no signs of inferior treated water quality were found based on the conductivity and salinity results. The removal of MPPs (size > 1.2 & mu;m) in DCMD applications with seawater was analyzed by & mu;Raman, with all the results suggesting very high removal efficiencies (>99 %).

Automated summary

This study investigates the behavior of microplastic particles (MPPs) in a lab-scale direct contact membrane distillation system and analyzes their impact on the process performance. The temperature stress tests were performed on commercial MPPs, and uPVC was selected for further experiments. The results show that high loads of uPVC MPPs can decrease the distillation performance, but the treated water quality remains unaffected. The analysis also reveals that membrane distillation has a high efficiency in the removal of MPPs in seawater applications.