Experimental studies on the effect of harvesting interval on yield of Scenedesmus arcuatus var. capitatus

Absorption of CO2 and light in desired quantity plays a key role in photosynthesis for CO2 sequestration by microalgae. The growth of microalgae undergoes lag, log, stationary and deceleration phases resulting in increased growth rate upto an optimum biomass concentration and then decreased beyond that concentration. Variation of rate with biomass concentration affects the overall performance. Maintenance of growth rate always at the maximum level will reduce the reactor size and hence the cost. Therefore, a process strategy required for maintaining maximum growth rate of microalgae is proposed in the present study. The proposed strategy is to harvest the microalgae at periodic intervals to maintain the optimum biomass concentration inside the reactor by semi-continuous mode of operation. The effect of the proposed strategy on the overall yield was examined by conducting the experiments on the growth of Scenedesmus arcuatus var. capitatus with a culture depth of 0.5 cm by batch and semi-continuous modes. Comparing the yields, it is found that the proposed strategy increased the yield by 35% when harvested at a periodic interval of 5 h, over the batch mode.