RESEARCH ARTICLE
Cultivation, characterization, and properties of Chlorella vulgaris
microalgae with different lipid contents and effect on fast pyrolysis oil
composition
Ioannis-Dimosthenis Adamakis
1
&
Polykarpos A. Lazaridis
2
&
Evangelia Terzopoulou
1
&
Stylianos Torofias
2
&
Maria Valari
1
&
Photeini Kalaitzi
1
&
Vasilis Rousonikolos
1
&
Dimitris Gkoutzikostas
1
&
Anastasios Zouboulis
2
&
Georgios Zalidis
1
&
Konstantinos S. Triantafyllidis
2
Received: 13 November 2017 /Accepted: 22 May 2018 /Published online: 1 June 2018
#
Springer-Verlag GmbH Germany, part of Springer Nature 2018
Abstract
A systematic study of the effect of nitrogen levels in the cultivation medium of Chlorella vulgaris microalgae grown in
photobioreactor (PBR) on biomass productivity, biochemical and elemental composition, fatty acid profile, heating value
(HHV), and composition of the algae-derived fast pyrolysis (bio-oil) is presented in this work. A relatively high biomass
productivity and cell concentration (1.5 g of dry biomass per liter of cultivation medium and 120 × 10
6
cells/ml, respectively)
were achieved after 30 h of cultivation under N-rich medium. On the other hand, the highest lipid content (ca. 36 wt.% on dry
biomass) was obtained under N-depletion cultivation conditions. The medium and low N levels favored also the increased
concentration of the saturated and mono-unsaturated C16:0 and C18:1(n-9) fatty acids (FA) in the lipid/oil fraction, thus
providing a raw lipid feedstock that can be more efficiently converted to high-quality biodiesel or green diesel (via
hydrotreatment). In terms of overall lipid productivity, taking in consideration both the biomass concentration in the medium
and the content of lipids on dry biomass, the most effective system was the N-rich one. The thermal (non-catalytic) pyrolysis of
Chlorella vulgaris microalgae produced a highly complex bio-oil composition, including fatty acids, phenolics, ethers, ketones,
etc., as well as aromatics, alkanes, and nitrogen compounds (pyrroles and amides), originating from the lipid, protein, and
carbohydrate fractions of the microalgae. However, the catalytic fast pyrolysis using a highly acidic ZSM-5 zeolite, afforded a
bio-oil enriched in mono-aromatics (BTX), reducing at the same time significantly oxygenated compounds such as phenolics,
acids, ethers, and ketones. These effects were even more pronounced in the catalytic fast pyrolysis of Chlorella vulgaris residual
biomass (after extraction of lipids), thus showing for the first time the potential of transforming this low value by-product towards
high added value platform chemicals.
Keywords Microalgae
.
Chlorella vulgaris
.
Nitrogen-depleted cultivation
.
Lipids and residual biomass
.
Fast pyrolysis and
catalytic fast pyrolysis
.
Aromatic hydrocarbons
Introduction
The intensive use of fossil fuels has contributed to climate
change, environmental pollution, and related health issues.
The partial replacement of conventional petroleum fuels with
biofuels has been adopted over the last years as one of the
measures to mitigate these problems. Biodiesel (fatty acid
methyl esters, FAME) and HVO (hydrogenated vegetable
oil, often called as Bgreen diesel^), both being substitutes of
petroleum-derived transportation diesel, are currently pro-
duced from rapeseed oil (mainly), palm oil, used cooking
oil, animal fats, and soybean oil (Flach et al. 2017).
Microalgae have been recently considered as a promising,
Environmental Science and Pollution Research (2018) 25:23018–23032
https://doi.org/10.1007/s11356-018-2368-5
Responsible editor: Gerald Thouand
* Anastasios Zouboulis
zoubouli@chem.auth.gr
* Georgios Zalidis
zalidis@agro.auth.gr
* Konstantinos S. Triantafyllidis
ktrianta@chem.auth.gr
1
Laboratory of Applied Soil Science, School of Agriculture, Aristotle
University of Thessaloniki, 54124 Thessaloniki, Greece
2
Laboratory of Chemical and Environmental Technology, Department
of Chemistry, Aristotle University of Thessaloniki,
54124 Thessaloniki, Greece
@Phil_Robichaud
@deepthiw
@JoseServera