From waste to energy: Microalgae production in wastewater and glycerol Iago Teles Dominguez Cabanelas a,⇑ , Zouhayr Arbib a , Fábio A. Chinalia b , Carolina Oliveira Souza d , José A. Perales a , Paulo Fernando Almeida c , Janice Izabel Druzian d , Iracema Andrade Nascimento b a Environmental Technologies Department, CACYTMAR – Centro Andaluz de Ciencia y Tecnología Marinas, University of Cádiz (UCA), Spain b Marine Biology Lab (LABIOMAR), Biology Institute, University of Bahia, Brazil c Laboratory of Biotechnology and Ecology of Microorganism (LABEM), Health Sciences Institute, University of Bahia, Brazil d Department of Bromatological Analysis, Faculty of Pharmacy, University of Bahia, Brazil highlights  Highest biomass and lipid productivities where achieved at mixotrophic cultivation.  Lipids from mixotrophic biomass were more suitable for biodiesel production.  Nutrient removal achieved below the most strict threshold limits.  Positive energy production scenarios can be designed coupling distinct processes. article info Article history: Received 5 December 2012 Received in revised form 18 March 2013 Accepted 6 April 2013 Keywords: Wastewater Microalgae production Mixotrophic Glycerol Bioreﬁnery Energy production abstract The present work aimed to evaluate the auto/mixotrophic growth of microalgae using domestic waste- water (WW) amended with glycerol aiming biofuels production. The best results were obtained with the highest glycerol supplementation (50 mM). In such condition, Chlorella vulgaris and Botryococcus ter- ribilis showed a biomass productivity of 118 and 282 mg l 1 d 1 , which produced about 18 and 35 mg l 1 d 1 of lipids, respectively. Thus, if scaled-up (200 m 3 d 1 of WW, 240 working days y 1 ) bio- mass and lipid yields may be about 5.6 tons y 1 and 894.2 kg y 1 or 13.5 tons y 1 and 1.6 tons y 1 for C. vulgaris and B. terribilis, respectively. The mixotrophic production of lipids can generate high quality biodiesel according to estimations using their fatty acids proﬁles. The whole process can be advanta- geously combined with the production of other biofuels (e.g. methane and bio-ethanol) in a bioreﬁnery scenario. This combination of algal biomass production with waste treatment (WW amended with glyc- erol) can have a signiﬁcant impact in the water treatment sector and local markets. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction It is estimated that the volume of domestic efﬂuents generated by North America, Europe and Latin America is of approximately 70, 63 and 47 km 3 y 1 , respectively [1]. Thus, the current main challenge of a Wastewater Treatment Plant (WWTP) is not only to produce reusable clean water, but it is also to ﬁnd new technol- ogies for supporting such an activity [2]. Conventional techniques can remove only a fraction of the total nitrogen (40%) and phos- phorous (12%) present in the efﬂuent. In order to improve the pro- cess new methods (tertiary steps) and, consequently, additional costs are required [3]. The European Directive 98/15/EC establishes a threshold of 10 and 1 mg per liter for total N and P. WWTP efﬂu- ents commonly show N and P values around 20–70 and 4–12, respectively [3]. Therefore, there is still a clear need for new devel- opments and biological systems are often considered to be the ideal means for responding to such a demand [4]. The economic costs are, however, a primary concern once improved nutrients re- moval would require an overall increase in energy consumption of about 60–80% [5]. Therefore, in order to reduce costs, new systems should explore the combination of wastewater treatment with the production of renewable energy in order to offset ﬁnal costs [6,7]. Microalgae based systems have shown a high potential to assist with nutrient removal [8–10]. On the other hand, such a process can be improved if treatment is associated with generation of valu- able co-products [7]. Biofuels have been advocated as a suitable option to replace fossil fuels [11,12]. However, several social and environmental issues are associated with increasing land crops 0306-2619/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.apenergy.2013.04.023 ⇑ Corresponding author. Current address: AlgaePARC (Algae Production and Research Center), Wageningen University and Research Center (WUR), Bornsesteeg 10, Building 112, 6721NG, Bennekom, Netherlands. Tel.: +31 0652896128; fax: +31 0317482631. E-mail address: iago.dominguezteles@wur.nl (I.T.D. Cabanelas). Applied Energy 109 (2013) 283–290 Contents lists available at SciVerse ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy