A Modular Flat Panel Photobioreactor (MFPP) for indoor mass cultivation of Nannochloropsis sp. under artificial illumination

Abstract

Nannochloropsis sp. was grown in a Modular FlatPanel Photobioreactor (MFPP) consisting of sixalveolar panels each with 20.5 L culture volume and3.4 m2 illuminated surface area. The panelsformed a closely-packed unit with illuminationprovided by banks of fluorescent tubes placed betweenthe panels. The whole unit was contained in athermoregulated cabinet. Continuous illumination ofone side of the panels with 115 μmolphoton m-2 s-1 attained a mean volumetricproductivity of 0.61 g (d. wt) L-1 24 h-1,increasing to 0.97 g (d. wt) L-1 24 h-1 whenthe same irradiance was provided on both sides of thepanels. With 230 μmol photon m-2 s-1 onone side of the panel, a mean productivity of 0.85 g(d. wt) L-1 24 h-1 was achieved, whichreached 1.45 g (d. wt) L-1 24 h-1 when bothsides were illuminated. Increasing the amount of lightprovided to the culture (either by increasingirradiance or the illuminated surface area) decreasedpigment and enhanced the total fatty acid content, butdid not change significantly the content ofeicosapentaenoic acid. A MFPP of the presentdimensions could produce sufficient microalgae tosupport a hatchery producing 6 million sea breamfingerlings annually.