A study on the automatic harvest by on-off control for a combined system of continuous culture of microalgae and ultrasonic separation devices

Microalgae offer several advantages as renewable energy sources. To commercialize microalgae biofuel, the cost of microalgae product processing must be reduced. Mass culture and economical harvesting of microalgae are methods that can reduce the process cost. This paper proposes a separation method using ultrasonic waves for effective harvesting of microalgae. Experiments were conducted by considering four variables by ultrasonic separation process using the Taguchi method. Continuous culture of microalgae was performed based on the experimental results of the ultrasonic separation process. To harvest automatically microalgae in the process, an on-off control was implemented using the continuous culture and ultrasonic separation device to compose one combined system. Experiments were conducted on the combined system to increase production efficiency while simultaneously economically harvesting and performing mass culture of microalgae.