(660g) Optimization Study of Microalgae Dewatering By Utilizing Bio-Based Alkali

In the present study, the flocculating viability of bio-based alkali derived from cocoa pod husk ash was investigated by using the D-optimal design of the response surface methodology (RSM). And the interactive effects of biomass concentration and flocculant dose on flocculation efficiency and concentration factors were examined and the process was optimized using RSM. Under the optimum conditions of biomass concentration 0.54 g dry weight/L and flocculant dose 0.50 (% v/v), the maximum flocculation efficiency (92 %) and concentration factor (34) of Dunaliella salina were obtained. Meanwhile, the flocculation efficiency (95 %) and concentration factor (7) of Nannochloropsis oculata were obtained under the optimum condition of 0.83 g dry weight/L and 0.5 (% v/v) for biomass concentration and flocculant dose respectively. The result of elemental analysis of the bio-based alkali by ICP-MS showed that the concentration of K⁺ (51489 ppm) is highest followed by Ca²⁺ (1450 ppm) and Na⁺ (210 ppm). This undoubtedly shows the alkaline nature of the obtained bio-based alkali from cocoa pod husk ash that was employed as flocculant for harvesting microalgae. This study confirmed that produced cocoa pod derived alkali can be used to effectively and efficiently harvest microalgae from dilute microalgae culture medium.