Bench-scale dehydration of a native microalgae culture by centrifugation, flocculation and filtration in Minamisoma city, Fukushima, Japan

Abstract

Fukushima, northeastern Japan, was damaged by a tsunami and nuclear incident following the March 2011 earthquake. To make effective use of non-arable lands, an examination of biofuel production from native microalgal communities was carried out in Minamisoma city, Japan. After cultivation in open-air raceway ponds, the concentration of suspended solids (SS) of microalgae culture reaches 0.03 wt%. Efficient dehydration of microalgae is, therefore, essential. This study examined a bench-scale dehydration process composed of centrifugation, flocculation and filtration. A continuous centrifuge was used for primary concentration, and 14,600 kg of algal culture was dehydrated. After centrifugation, a cationic trimethylamine-type polymer as flocculant was added to the primary concentrate, and mixed. The mixture was processed by a continuous vacuum filtration and compression, and 12.9 kg of concentrate was obtained with 82.7% recovery. Through this process, SS concentration reached a satisfactory value of 24.6 wt% with the high throughput of 5920 kg/h.