ASTAXANTHIN INDUCTION OF HAEMATOCOCCUS PLUVIALIS IN FLAT PANEL AIRLIFT PHOTOBIOREACTORS

Abstract

This work studied astaxanthin induction from H.pluvialis (NIES-144) using flat panel airlift photobioreactors (FP-APBRs) under indoor and outdoor conditions. Preliminary experiments in 1.5 L bubble column photobioreactors (BC-PBR) revealed that sterilized clean water with 3% CO2 aeration (1.47 cm3 s-1 CO2 loading), 35,000 LUX and 330C could best encourage astaxanthin accumulation at 18.21 g m-3 (3.63% by weight). Operating 17 L FP-APBR with these bubble column parameters under the downcomer to riser cross sectional area ratio (Ad/Ar) of 0.4 and superficial gas velocity of 0.4 cm s-1 could further enhance astaxanthin to 26.63 g m-3 (5.34% by weight). For the operation of the one-step process system, reducing nitrate and phosphate at 4 and 6-fold of that in the original F1 medium could best encourage astaxanthin accumulation at 28 g m-3 (5.24% by weight). However, similar operation under outdoor condition exhibited slightly poorer performance due to the light inhibition effect. The best outdoor performance was obtained with the FP-APBR covered with 1-layer shading net on the first few days (1-3 days) where 20.9 g m-3 (4.45% by weight) of astaxanthin was resulted. In addition, the various sizes of FP-APBRs exhibited similar performance implying a potential scale-up opportunity. In case of annual cost estimations of astaxanthin induction, results indicated that outdoor system charges were cheaper because this system did not require the use of fluorescent lamps as a light source for astaxanthin induction.