A filtration photobioreactor (FPBR) has been designed in this study. It requires a much shorter time to start up than existing biofilm systems, while providing easy biomass harvest. Microalgae are retained on a membrane through filtration so that microalgae growth is spatially separated from nutrient discharge and recharge. Therefore, additional processes for removing viable cells from spent medium are not required, and CO2 transfer efficiency into the medium can be improved without affecting cell growth. Performance of the FPBR for Chlorella sp. cultivation has been studied under various operating conditions, and an operating time and initial cell concentration for achieving optimum productivity has been selected. With a medium recycle rate of 5 mL min(-1) and a feed gas containing 73% CO2, the biomass productivity was 13.56 g m(-2) d(-1) as the cell concentration increased from 2.54 to 20 g m(-2) at 35 degrees C, which was higher than that achieved in a biofilm system for Chlorella sp. cultivation.