Investigation of effective Parameters on Electroflocculation in microalgae harvesting from broth for food product purposes

One of the problems existing in microalgae production process for the food products is the lack of suitable method for harvesting the microalgae from broth. Nowadays، centrifugation is the only industrial method for microalgae harvesting and its harvesting efficiency is approximately 92%، but the cost of centrifugation is high. In this paper، a new method called electroflocculation was innovated for separation of microalgae from broth and effective parameters in increasing the efficiency of this method were investigated. For achieving this goal، first a special setup which was suitable for microalgae harvesting was designed and fabricated to simulate several harvesting parameters. Then using the designed setup، several parameters such as the mixing type، mixing intensity، current rate، distance and contact area of electrodes، time and power consumption were measured and compared. Results showed that in electroflocculation method the mechanical mixing with 100 rpm intensity and current rate of 5 A has the efficiency of 98%. One cm electrode gap and 640 cm2 contact area were suitable and during 30 minutes the harvesting efficiency of 98% was achieved. The power consumption for harvesting of 1 kg microalgae was 1 kW. h for electroflocculation method which is five times less than typical centrifugation.