The wastewater collected from the port sewage treatment plant was treated by using 2 types of polypropylene membranes with a porosity of 73%, and a pore size of 0.2 pm but differing in thickness. A decrease in the process efficiency due to membrane fouling was found during the 1000 h long test. The filter cake was removed by washing with 3% HCI. The morphoL and compn. was studied by scanning electron microscopy coupled with energy-dispersing spectrometry. Regardless of the sewage compn., a high quality water was obtained in each studied case.