Cranfield University, Cranfield, United Kingdom.
University of Duisburg-Essen, Essen, Germany.
Water Res. 2014 Apr 15;53:168-79. doi: 10.1016/j.watres.2014.01.012. Epub 2014 Jan 24.
Dissolved Air Flotation (DAF) is a well-known coagulation-flotation system applied at large scale for microalgae harvesting. Compared to conventional harvesting technologies DAF allows high cell recovery at lower energy demand. By replacing microbubbles with microspheres, the innovative Ballasted Dissolved Air Flotation (BDAF) technique has been reported to achieve the same algae cell removal efficiency, while saving up to 80% of the energy required for the conventional DAF unit. Using three different algae cultures (Scenedesmus obliquus, Chlorella vulgaris and Arthrospira maxima), the present work investigated the practical, economic and environmental advantages of the BDAF system compared to the DAF system. 99% cells separation was achieved with both systems, nevertheless, the BDAF technology allowed up to 95% coagulant reduction depending on the algae species and the pH conditions adopted. In terms of floc structure and strength, the inclusion of microspheres in the algae floc generated a looser aggregate, showing a more compact structure within single cell alga, than large and filamentous cells. Overall, BDAF appeared to be a more reliable and sustainable harvesting system than DAF, as it allowed equal cells recovery reducing energy inputs, coagulant demand and carbon emissions.
气浮（DAF）是一种广泛应用于大规模微藻收获的著名混凝气浮系统。与传统的收获技术相比，DAF 可以在较低的能耗下实现更高的细胞回收率。通过用微球代替微气泡，创新的压载式气浮（BDAF）技术已被报道可以达到相同的藻类细胞去除效率，同时节省传统 DAF 装置所需能量的 80%。本工作使用三种不同的藻培养物（斜生栅藻、普通小球藻和极大螺旋藻），研究了 BDAF 系统与 DAF 系统相比在实际应用、经济和环境方面的优势。两种系统都实现了 99%的细胞分离，但 BDAF 技术可根据藻类种类和采用的 pH 值条件，将混凝剂用量减少多达 95%。就絮体结构和强度而言，微球的加入使藻类絮体生成更疏松的聚集体，在单细胞藻类内显示出更紧凑的结构，而不是大的丝状细胞。总的来说，BDAF 似乎是一种比 DAF 更可靠和可持续的收获系统，因为它可以在减少能源投入、混凝剂需求和碳排放的情况下实现同等的细胞回收。
