The opposite trend of PnSB and SRB suggested that there was a competitive relationship among them. The growth of PSB associated with SRB was also observed at high organic loading rate as PSB could utilize sulfide produced from SRB activities for their growth. Chl.a was found abundant in the photo-bioreactor without infrared transmitting filter since visible wavelength could be easily absorbed by microalgae during photosynthesis. The use of infrared transmitting filter was found effective for suppression of microalgae growth.