Effective harvesting of high-density microalgae biomass via combination of advanced oxidation and flocculation-flotation process

초록

The transition toward high-density microalgae cultivation has become essential for improving biomass productivity and spatial efficiency in microalgae biorefinery. However, harvesting for high-density biomass has not been explored intensively, and even considered as a bottleneck since the performance declines as the culture density increases. To address this issue, a new harvesting strategy, AOP-FFP, a combination of flocculation-flotation process (FFP) with advanced oxidation process (AOP) was proposed here. At a biomass concentration of 2.0 g L-1, the AOP-FFP system alleviated the inhibitory influence of algal organic matter (AOM) and increased the final harvesting efficiency by 11.1 +/- 2.1% compared to non-AOP process (FFP only). Since excessive UV/H2O2 in AOP could damage cell surfaces, the treatment intensity was optimized to maintain cell integrity, correlated with the flocculation performances. The effect of optimized AOP treatment in alleviating flocculation inhibition became more noticeable with increasing polysaccharide concentration, indicating that the combined process effectively prohibits the negative influence of polysaccharide-rich AOM in high-density cultures. Furthermore, AOP-FFP achieved harvesting efficiency comparable to that of FFP despite using 25% less flocculant, reducing biomass harvesting costs by approximately $0.3 kg(-1). These results demonstrate that the AOP-FFP system is quite effective for harvesting high-density microalgae biomass. Each step, AOP and FFP is a scalable and energy-efficient process, and the combined harvesting process, proposed here, could contribute to the industrial-scale biorefinery of microalgae biomass.

키워드