Harvesting of cyanobacterium Arthrospira platensis using inorganic filtration membranes

The present work deals with the concentration and the separation of Arthrospira platensis from a diluted culture medium. Among the different ways to operate this liquid/solid separation, this paper is focused on the membrane alternative. The general framework of this experimental study is the MELISSA project from the European Space Agency (ESA) for the development of life support systems in Space. The performances of fourteen inorganic membranes (microfiltration and ultrafiltration) were evaluated. According to the results, the operating conditions and the influence of phycocyanin and exopolysaccharides on the fouling phenomenon were investigated on the best membrane. A critical aspect to monitor along the process is the quality of the product in terms of composition of the main cell macro-components, such as proteins and exopolysaccharides. The ultrafiltration membrane ATZ-50 kD exhibited the best permeation flux and cleanability. An increase of fluid velocity and transmembrane pressure is energy-consuming. A good compromise between this consideration and the gain in terms of permeation flux is close to 3 m center dot s(-1) and 2 center dot 10(5) Pa with the selected membrane and with a cyanobacteria suspension concentration ranging from 50 mg center dot L-1 to 1 g center dot L-1.