Hydrogen recovery from the photovoltaic electroflocculation-flotation process for harvesting Chlorella pyrenoidosa microalgae Abdellatif Rahmani a,b , Djamal Zerrouki a,* , Lahc  ene Djafer b , Andr  e Ayral c a Univ. Ouargla, Fac. des Sciences Appliquees, Lab. Dynamique Interaction et Reactivites des Systemes, BP 511, Route de Ghardaı¨a, Ouargla, 30000, Algeria b Laboratoire Eau Environnement, Universite Hassiba Ben Bouali, BP 151, 02000, Chlef, Algeria c Institut Europeen des Membranes, UMR 5635 (CNRS-ENSCM-UM), Universite de Montpellier, Place E. Bataillon, F-34095, Montpellier, France article info Article history: Received 3 April 2017 Received in revised form 10 June 2017 Accepted 14 June 2017 Available online xxx Keywords: Harvesting Electro-flocculation Hydrogen Recovery Microalgae Photovoltaic abstract In this paper, an integrated process using photovoltaic power to harvest microalgae by electro-flocculation (EF) and hydrogen recovery is presented. It is mainly favorable in re- gions with high solar radiation. The electro-flocculation efficiency (EFE) of Chlorella pyr- enoidosa 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 ob- tained 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. © 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction Microalgae biomass utilization for low-value products, such as biofuel, fish and animal feed, biodiesel [1], and protein must take into account various factors to aid in ensuring an economically feasible process [2]. Low-cost microalgae biomass is currently regarded as unfeasible due to the high cost associated with cultivation and processing required. Major bottlenecks to the technology include nutrient supply, water footprint, harvesting and extraction of lipids due to the low value of the final product [3]. The cost of energy consumed to produce biomass must be significantly lower, than the cost of the product that can be harnessed from the resulting biomass. The environmental impacts using fossil fuel in the process must be weighed against the benefits of the resulting algal biofuel sustainability [3,4]. Abbreviations: EF, electro-flocculation; EFE, electro-flocculation efficiency; ECF, electro-coagulation flotation. * Corresponding author. E-mail address: Djamal.zerrouki@gmail.com (D. Zerrouki). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2017) 1 e6 http://dx.doi.org/10.1016/j.ijhydene.2017.06.123 0360-3199/© 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Rahmani A, et al., Hydrogen recovery from the photovoltaic electroflocculation-flotation process for harvesting Chlorella pyrenoidosa microalgae, International Journal of Hydrogen Energy (2017), http://dx.doi.org/10.1016/ j.ijhydene.2017.06.123