An advanced treatment of secondary treated wastewater by reverse osmosis membrane: The results of three condinuous running tests

The authors tried to apply reverse osmosis (RO) membrane to the advanced treatment of secondary treated wastewater (STW) discharged from the working sewage treatment plant. RO membrane was set in the Tojino village sewage treatment plant and three kinds of long term running tests were carried out. At the beginning of each test, the used membrane was exchanged for new one. The results of three tests indicate the following: (1) The flux of the advanced treated wastewater decreases with time due to attaching of contaminants on the surface of the membrane, (2) The removal rate of T-N decreases with the increase of NH4-N contained in the supplied wastewater in the case of T-N being constant, (3) PAC is effective for flocculation of contaminants in the STW, (4) The removal rate of contaminants decreases as a period of a running test gets longer, (5) PAC can lead the pre-treating device to be stuffed up, (6) The results of running tests show the different trends depending upon the water qua