Civil Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland; School of Civil Engineering, Hefei University of Technology, Hefei, China.
Civil Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland.
Sci Total Environ. 2022 Sep 10;838(Pt 1):155866. doi: 10.1016/j.scitotenv.2022.155866. Epub 2022 May 12.
Microalgae have great potential for biofuel production and wastewater treatment, but the high cost of harvesting hinders their practical application. In this study, economical harvesting of hydrophobic microalgae by electro-flotation without coagulation was assessed. The harvesting performance of this method for selected species of freshwater microalgae with different degrees of hydrophobicity (Tribonema sp., highly hydrophobic; Scenedesmus sp., moderately hydrophobic; and Pandorina sp., hydrophilic) were compared. It was found that microalgal hydrophobicity played a critical role in electro-flotation. Under the same condition (current 0.3 A, velocity gradient 200 s, biomass concentration 1 g/L), Tribonema sp. could be effectively harvested (96.2 ± 0.4%) after 20 min of electro-flotation, while the harvesting efficiency decreased significantly with Scenedesmus sp. (70.1 ± 5.2%, 20 min) and Pandorina sp. (<10%, 1 h). The influences of current, electrolysis time, mixing intensity (velocity gradient) and biomass concentration on Tribonema sp. (hydrophobic) harvesting were further investigated. Increasing the current within a certain range (0.1 A-0.4 A) was beneficial to harvesting, while it's further increase decreased floating velocity, which was similar to the effect of the velocity gradient. Under the optimal condition, the harvesting efficiency of Tribonema sp. was 96.3% and the energy consumption (0.19 kWh/kg biomass) was much lower than other harvesting techniques, indicating that electro-flotation is a time-saving and economical approach for hydrophobic microalgae harvesting.
微藻在生物燃料生产和废水处理方面具有巨大的潜力，但由于收获成本高，限制了其实际应用。本研究评估了不使用凝聚剂的电浮选经济有效地收获疏水性微藻。比较了不同疏水性（Tribonema sp.，高度疏水性；Scenedesmus sp.，中度疏水性；和Pandorina sp.，亲水性）的淡水微藻对所选物种的收获性能。结果表明，微藻疏水性在电浮选中起着关键作用。在相同条件下（电流 0.3 A，速度梯度 200 s-1，生物质浓度 1 g/L），Tribonema sp. 在电浮选 20 min 后可有效收获（96.2±0.4%），而 Scenedesmus sp. 和 Pandorina sp. 的收获效率显著降低（70.1±5.2%，20 min；<10%，1 h）。进一步研究了电流、电解时间、混合强度（速度梯度）和生物质浓度对 Tribonema sp.（疏水性）收获的影响。在一定范围内增加电流（0.1 A-0.4 A）有利于收获，而进一步增加电流会降低浮速，这与速度梯度的影响相似。在最佳条件下，Tribonema sp. 的收获效率为 96.3%，能耗（0.19 kWh/kg 生物质）远低于其他收获技术，表明电浮选是一种节省时间和经济的疏水性微藻收获方法。
