Hydrogen recovery from the photovoltaic electroflocculation-flotation process for harvesting Chlorella pyrenoidosa microalgae

In this paper, an integrated process using photovoltaic power to harvest microalgae by electro-flocculation (EP) and hydrogen recovery is presented. It is mainly favorable in regions with high solar radiation. The electro-flocculation efficiency (EFE) of Chlorella pyrenoidosa microalgae was investigated using, various types of electrodes (aluminum, iron, zinc, copper and a non-sacrificial electrode of carbon). The best results regarding the EFE, and biomass contamination were achieved with aluminum and carbon electrodes where the electrical energy demand of the process for harvesting 1 kg of algae biomass was 0.28 and 0.34 kWh, respectively, while the energy yield of harvested hydrogen was 0.052 and 0.005 kWh kg(-1), respectively. The highest harvesting efficiency of 95.83 +/- 0.87% was obtained with the aluminum electrode. The experimental hydrogen yields obtained were comparable with those calculated from theory. With a low net energy demand, microalgae EF may be a useful and low-cost technology. (c) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.