Integrated process for the production of carbohydrates and lipids by cultivation of Scenedesmus sp. with olive mill wastewaters

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1 Integrated process for the production of carbohydrates and lipids by cultivation of Scenedesmus sp. with olive mill wastewaters Fabrizio Di Caprio 1, Pietro Altimari 1,2, Iryna Boika 1, Luigi Toro 1,2, Francesca Pagnanelli 1,2 1 Department of Chemistry, Sapienza University of Rome 2 Ecorecycling srl 1

2 Microalgal biorefinery Sunlight Biodiesel CO2 Water Biomass Bioethanol Biohydrogen Inorganic salts Biogas 2

3 Microalgal production systems Main advantages Application of renewable resources Large biomass productivity per unit area larger than any terrestrial plant Absence of competition for arable lands Large fractions of lipids (more than 50% w/w) Limits to economic sustainability Elevated cost of equipment (mainly photobioreactors) Elevated consumption of nutrients Risk of contamination Large energy consumption (downstream refinery) 3

4 Towards process intensification Possible strategies Full exploitation of any microalgal fraction allowing for the simultaneous realization of multiple products of industrial interest Selection or genetic based realization of Development of more energetically efficient separation solutions (pulsed electric field, switchable solvents) Anaerobic digestion of residual biomass and recycle of digested to cultivation reactors Application of wastes (as, for example, urban wastewaters and agro-industrial wastes) as sources of nutrients 4

5 Application of olive mills wastewaters phenols sugars sospended u solids total solids dry residue (%) H 2 O (%) COD ph PO 4 -- density Parameter (g l -1 ) (g l -1 ) (ml l -1 ) (g l -1 ) (g l -1 ) (mg l -1 ) (g ml -1 ) Value ± Main advantages in microalgal cultivation Transition to heterotrophic growth regime allowing for the application of reactors with lower surface to volume ratio Simultaneous biomass production and depuration of OMW through degradation of phenols by microalgae. Increase in the fraction of accumulated carbohydrates and/or lipids by direct exploitation of OMW organic carbon. 5

6 Investigated effects Addition of unsterilized OMW Experimental design Possibility to replace distilled water with tap water Addition of micronutrients OMW 9% (v/v) BG11+OMW TWBM+OMW OMW 0% (v/v) BG11 TWBM BG11 TWBM BG11 : distilled water with NO 3-, PO4 3- and micronutrients TWBM: tap water with NO 3-, PO4-3 6

7 Strain selection The strain Scenedesmus sp. was selected during the start-up of pilot plant operated at Priolo Gargallo in autotrophic regime The strain was the one among those tested capable of sustaining satisfactory growth on pilot scale Research Project Alghe Energetiche 7

$target fractions Biomass production Carbohydrates and$

8 Analysis of biomass production and accumulation of target fractions Biomass production Carbohydrates and Lipids 8

$Analysis of biomass production and accumulation of target fractions$

9 Analysis of biomass production and accumulation of target fractions Biomass production Removal of organic fraction and of phenols BG11+OMW TWBM+OMW 9

10 Optimization of OMW supply strategy Biomass production Removal of carbohydrates from OMW Addition of OMW Carbohydrates removal (%) 10

11 Optimization of OMW supply strategy Biomass production Accumulated lipids and carbohydrates Addition of OMW 11

12 Conclusions The addition of inorganic nitrogen to OMW prevents a reduction of the specific growth rate The addition of OMW to culture medium in bacth mode determines a reduction of biomass productivity. The reduction in biomass productivity is balanced by an increae in the accumulated fraction of carbohydrates Micronutrients appear to play a fundamental role in the degradation of phenols Fed-batch stragegy can prevent the early achievement of stationary phase allowing for a significant increase in biomass and carbohydrates productivities 12

13 Conclusions x-x 0 (g l -1 ) TWBM - OMW TWBM BG11 - OMW 0.22 ± ± ± 0.09 BG ± Carbohydrates production (g l -1 ) Lipids production (g l ± ± ± ) 0.09 ± ± ± ± ± Maximum biomass productivity (g l -1 d -1 ) μ (d -1 ) 0.06 ± ± ± 0.01 C f,phenols (g l -1 ) * 0.42 ± ± ± C f,reducible sugars (g l -1 ) * 0.26 ± ± C f,cod (g l -1 ) * 2.83 ± ±

Two Stage Process of Microalgae Cultivation for Starch and Carotenoid Production

Two Stage Process of Microalgae Cultivation for Starch and Carotenoid Production 415 A publication of CHEMICAL ENGINEERING TRANSACTIONS VOL. 49, 2016 Guest Editors: Enrico Bardone, Marco Bravi, Tajalli Keshavarz Copyright 2016, AIDIC Servizi S.r.l., ISBN 978-88-95608-40-2; ISSN 2283-9216