Effect of Optical Panal Distances on the Growth Rate of Chlorella vulgaris in a Photobioreactor

Abstract : The aim of this study is to optimize the efficiency of a photobiorector on the growth rate of Chlorella vulgaris ( C. vulgaris ) by varying distance of optical panel (OP). The round shaped C. vulgaris (FC-16) having the size of 3-8 µm is employed in this study. The cells of C. vulgaris are cultured in the Jaworski’s Medium with deionized water at 22℃ for 15 days. The OP is placed at four different distances i.e., at 225 mm distance (Run 1), 150 mm distance (Run 2), 112.5 mm distance (Run 3) and 90 mm distance (Run 4) having a LED (Light Emitting Diode) source. The diffuse rate is achieved to 86%, 90%, 92% and 94% for Run 1, Run 2 Run 3 and Run 4, respectively. A narrower distance of OP caused to effectively to increase the efficiency of diffuse light rate. For mass cultivation of this biomass, medium is changed according to distance of OP after attaining a maximum biomass concentration; Run 1 in 8 days, Run 2 in 6 days, Run 3 in 4 days and Run 4 in 3 days. In addition, the amount of maxi-mum biomass rate for Run 4 was reached 3 times higher than that of Run1. However, growth rate, chlorophyll per cell, cell volume and doubling time are found to be Run 3 and Run 4 higher than that of Run 1 and Run 2 samples. However, Run 3 and Run 4 are having a slight difference in all these measurements. These findings suggest that in terms of economic consideration and effi-ciency towards simultaneous mass cultivation of biomass, Run 3 was found to be more effective than other samples.