The researchers studied how adding a coagulation step before using microfiltration can improve the treatment of phosphorus-containing wastewater from car painting. They found that coagulation reduced membrane fouling, increased permeate flux, and significantly improved phosphate removal compared to direct microfiltration. The treated water met national standards and could be safely reused. Cleaning the membrane after coagulation resulted in higher permeate flux recovery due to differences in cake layer formation.