Dunaliella salina Harvesting Using Spiral Electrocoagulation and Parameters Optimization Using Response Surface Method

Dunaliela salina has advantages over other microalgae species, including rapid growth, high salt concentration, simple growth requirements, and fast production. However, the harvesting process of D. Salina requires a particular harvesting method due to its tiny size. This research aims to develop an effective D. Salina harvesting method using spiral electrocoagulation (SEC). Optimization of operating parameters including initial D. Salina concentration, voltage, reactor slope, and electrocoagulation time is carried out using response surface methodology (RSM) to maximize the D. Salina harvesting process analysis of wastewater quality produced shortly after the harvesting process. The results showed that the optimum operation for D. Salina harvest until a harvesting efficiency of 85.77% was achieved required 25 V; 4.17 min as a time of electrocoagulation; 68,39 degrees as the angle of the reactor; and 25% initial concentration of D salina. The variable voltage, time, and initial concentration of D. Salina significantly affect harvesting efficiency, while the reactor angle has an insignificant impact. Based on the Central Composite Design (CCD) design, the minimum COD concentration is 3.36 mg/L when SEC operations use a voltage of 25V, time of electrocoagulation 5 min, angle of reactor 75-degree, and concentration of D. Salina 70% of the initial concentration. The concentration of nutrients (nitrate, phosphate, ammonia) produced after the harvesting process varies depending on variations in voltage, time, angle of reactor, and initial concentration of D. salina.