The harvesting of microalgae is the main bottleneck of its large-scale biomass production, and seeking an efficient, green, and low-cost microalgae harvesting technology is one of the urgent problems to be solved. Microbubble air flotation has been proven to be an effective measure, but the mechanisms of microbubbles-algal cell attachment are still unclear. In this study, microbubble air flotation was used as a harvesting method for Microcystis cultured in agricultural wastewater. The process mechanism of microbubble air flotation harvesting microalgae in wastewater was fully revealed from three aspects (the design of bubble formation, the adhesion law, and the recovery rate of microalgae under different working conditions). The results show that the length of the release pipe is the main factor affecting the proportion of microbubbles with a particle size of less than 50 μm. In the process of adhesion, when the particle size of microbubbles is 0.6–1.7 times the size of Microcystis, the adhesion efficiency of microbubbles to Microcystis is the highest. Under the conditions of pressure 0.45 MPa, gas–liquid ratio 5%, and release pipe length 100 cm, the harvesting performance of Microcystis was the best. Microbubble air flotation has better harvesting performance (63.5%, collection rate) of Microcystis with higher density. By understanding the mechanism of microbubble flotation, the technical parameters of microbubble flotation for harvesting energy microalgae are optimized to provide support for the development of efficient and low-cost devices and equipment for collecting microalgae.

中文翻译：

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微气泡气浮法从农业废水中收集微囊藻的应用：调控及机制


微藻的收获是其大规模生物质生产的主要瓶颈，寻求一种高效、绿色、低成本的微藻收获技术是亟待解决的问题之一。微气泡气浮已被证明是一种有效的措施，但微气泡-藻类细胞附着的机制仍不清楚。在本研究中，微气泡气浮被用作农业废水中培养的微囊藻的收集方法。从气泡形成设计、粘附规律、不同工况下微藻回收率3个方面充分揭示了微泡气浮收收集废水中微藻的工艺机理。结果表明：释放管的长度是影响粒径小于 50 μm 的微气泡比例的主要因素。在粘附过程中，当微泡的粒径为微囊藻大小的 0.6-1.7 倍时，微泡对微囊藻的粘附效率最高。在压力 0.45 MPa、气液比 5%、释放管长度 100 cm 的条件下，微囊藻的采集性能最好。微泡气浮对密度较高的微囊藻具有较好的收获性能 （63.5%，收集率）。通过了解微气泡浮选的机理，优化了微气泡浮选收集能量微藻的技术参数，为高效、低成本的收集微藻装置和设备的发展提供了支撑。