Bioresource Technology 269 (2018) 571–576
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Bioresource Technology
journal homepage: www.elsevier.com/locate/biortech
Short Communication
An integrated approach for microalgae cultivation using raw and anaerobic
digested wastewaters from food processing industry
Suvidha Guptaa, Sanjay B. Pawarb,
T
⁎
a
Academy of Scientific and Innovative Research (AcSIR), Environmental Biotechnology and Genomics Division (EBGD), CSIR-National Environmental Engineering
Research Institute (NEERI), Nagpur, India
b
Environmental Biotechnology and Genomics Division (EBGD), CSIR-National Environmental Engineering Research Institute (NEERI), Nagpur, India
G R A P H I C A L A B S T R A C T
A R T I C LE I N FO
A B S T R A C T
Keywords:
Waste to bioenergy
Biodiesel
Anaerobically digested wastewater
Cost-effective cultivation
Food industry effluent
An integrated approach has been proposed to produce microalgal biodiesel using both raw wastewater (RW) and
anaerobically digested wastewater (ADW) of food processing industry without addition of extra nutrients or
carbon source for cultivation besides obtaining effluent discharge permissible limits of TN, TP, and COD. Three
microalgae species cultivated with following different combinations: RW, ADW, RW + ADW, and
glucose + ADW. Results indicated that the addition of RW as a carbon source in ADW significantly enhanced BP,
LP, and TN removal as compared to the ADW alone. The runs with RW + ADW removed COD, TN, and TP by
89%, 84%, and 70%, respectively. Sc. obliquus showed highest biomass and lipid productivities (211 and
27.5 mg L−1 d−1) for RW + ADW. The addition of RW or glucose in ADW significantly lowered PUFA contents to
5–15% CDW (as against 35–50% with ADW) for Chl. sorokiniana and Sc. obliquus.
1. Introduction
Due to the ever-increasing demand for energy worldwide, a lot of
attention has been given to renewable energy sources. The potential of
wastewater for large-scale microalgae cultivation in the context of reduction in both production costs and environmental impact has been
emphasized by Mayers et al. (2017) and Pawar (2016). Food industrial
⁎
effluent contains a higher amount of biodegradable organic carbon
compounds (proteins, fats, and carbohydrates) with elevated values of
total nitrogen and total phosphate (Senturk et al., 2010; Ji et al., 2015).
The general practice to treat this wastewater is anaerobic digestion to
produce biogas due to its higher biodegradability (Senturk et al., 2010).
However, the anaerobically digested wastewater (ADW) further needs
treatments due to a significant amount of nutrients (ammonical
Corresponding author at: EBGD, CSIR-NEERI, Nehru Marg, Nagpur 440020, India.
E-mail addresses: sb_pawar@neeri.res.in, sanjay6282@gmail.com (S.B. Pawar).
https://doi.org/10.1016/j.biortech.2018.08.113
Received 9 July 2018; Received in revised form 25 August 2018; Accepted 27 August 2018
Available online 29 August 2018
0960-8524/ © 2018 Elsevier Ltd. All rights reserved.
Bioresource Technology 269 (2018) 571–576
S. Gupta, S.B. Pawar
Fig. 1. Time course profiles of cell dry weight of different microalgae species cultivated on RW, ADW, RW + ADW, and Glucose + ADW, a) Chl. sorokiniana, b) Sc.
obliquus, c) Sc. abundans, and d) specific growth rates for three microalgae species.
Bold Basal Media (BBM) (see Supplementary file).
nitrogen and phosphate) remaining after its digestion (Farooq et al.,
2013; Darpito et al., 2015; Koutra et al., 2017; Zheng et al., 2018).
Further, the addition of carbon-rich wastewater in carbon deficient
wastewater would be a great choice to facilitate nutrient’s removal
instead of the addition of costly synthetic substrates such as glucose or
acetate (Zheng et al., 2018; Tan et al., 2018).
In the current work, the food products (snacks) processing industrial
wastewater, collected before and after anaerobic digester (AD) from the
same plant, was used for microalgae cultivation. Thus, this study primarily evaluates the feasibility of both raw wastewater (RW) and AD
effluent in the contexts of biomass and lipid productivities and nutrients
removals. Further, an integrated approach was investigated in which
RW mixed with carbon deficient ADW as an extra supplement of organic carbon to enhance the removal rate of total nitrogen from ADW.
The outcomes were also compared with the runs in which glucose
added to ADW (equivalent amount of carbon to that in raw wastewater). Thus, the study aims to examine the feasibility of an integrated
process of biodiesel production based on wastewater treatment facility
with no addition of synthetic organic carbon and nutrients.
2.2. Characteristics of the wastewaters
The wastewaters, before and after AD unit, were collected from a
nearby food factory (Nagpur, India). This is an Indian snack industry
which produces processed food products (snacks) from legumes, potato,
nuts, soya, wheat flour, and milk. The wastewaters collected for this
study from its central wastewater treatment plant contained wastewaters from all these plants. The wastewaters were kept for 24 h to
settle down the suspended solids and then separated clear solution was
filtered through nylon mesh strainer (∼50 µm) and stored at 4 °C before
the experiments. The raw wastewater (RW) and anaerobically digested
wastewater (ADW) were analyzed for physicochemical parameters and
presented in the Supplementary file.
2.3. Experimental set-up
RW and ADW were centrifuged before experimentation at 6000 rpm
for 20 min (REMI PR-23, Remi Elektroteknik Ltd., India) and then
sterilized in an autoclave. The sterilized RW and ADW were used for all
experiments. The initial values of chemical oxygen demands (CODs) of
RW and ADW after sterilization were 7146 and 128 mg L−1, respectively. The pH of ADW was adjusted to 7 before conducting the experiments by sparging CO2 into the flasks containing ADW. RW was
diluted with distilled water (21% RW) to get initial COD of
1500 mg L−1. The experiments were carried out for the following cases:
RW (initial COD: 1500 mg L−1; total nitrogen (TN): 30 mg L−1), ADW
2. Materials and methods
2.1. Microalgae strains
Three freshwater microalgae strains, Chlorella sorokiniana (NCIM
No. 5561), Scenedesmus obliquus (NCIM No. 5586), and Scenedesmus
abundans (NCIM No. 2897), were obtained from NCIM-NCL, Pune, India
for this study. The microalgae strains were maintained and cultivated in
572
Bioresource Technology 269 (2018) 571–576
S. Gupta, S.B. Pawar
(initial COD: 128 mg L−1; TN: 172 mg L−1), RW + ADW (initial COD:
1500 mg L−1; TN: 166 mg L−1; 20% RW + 80% ADW), and
glucose + ADW (initial COD: 1500 mg L−1; TN: 172 mg L−1). Each
500 mL conical flask contained 280 mL of wastewater and 70 mL of
microalgae inoculum of each species. The total suspended solids were
below 40 mg L−1 for both wastewaters. The experimental conditions
were as follow: Light intensity-80 µmol m−2 s−1; ambient maximum
temperature-29 °C; light: dark cycle-10 h: 14 h; aeration-0.1 vvm (fish
tank aerator for 10 h in a day). CO2 was purged 3 times in a day in each
flask (except RW) to maintain pH between 7 and 8. The experiments
were carried out in triplicate.
Similarly, Sc. abundans also showed enhancement in COD removal for
the cases of RW and glucose additions in ADW (Fig. 2c).
From Fig. 2, it can be seen that COD was being removed until the
fourth day for all runs, but after that, there was no further consumption.
It could be because all biodegradable carbon compounds could have
been utilized by that time. A previous study on food industry wastewater (initial COD: 3000 mg L−1) reported COD removal of 90% using
isolated Chl. species (Gupta et al., 2016). Further, it can be seen that TN
removal of 100% was obtained within four days for RW by all three
microalgae species probably due to low initial TN concentration
(30 mg L−1) that could have been easily utilized. On the other hand, TN
removals of 49.1%, 44.3%, and 41.4% were accomplished by Chl. sorokiniana, Sc. obliquus, and Sc. abundans, respectively for ADW. However, the addition of RW in ADW (RW + ADW) showed TN removal up
to 84.5% (1.91 times higher than ADW) for Sc. obliquus and ∼82% for
both Chl. sorokiniana and Sc. abundans (1.66 and 1.99 times higher than
ADW respectively). It can also be seen that maximum TN removals for
RW + ADW and Glucose + ADW were obtained within just 3–4 days
for all three microalgae species. It can also be understood from COD
reduction data that as long as sufficient amount of carbon was present
in the medium, the removal of TN was fast and vice versa for COD
removal. Similar findings were reported by Zheng et al. (2018), in
which only 19% of NH4–N was removed from mixed piggery-brewery
malting wastewater due to the presence of a lot of residual nitrogen and
insufficient carbon source.
The removal of ammonical nitrogen was also measured using
Nessler reagents at the end of runs which showed a similar removal
percent (∼45% for ADW, and > 80% for RW + ADW and
Glucose + ADW) as that of TN for all three microalgae species. TP assimilation profiles for RW, ADW, RW + ADW, and Glucose + ADW are
shown in Fig. 2d. The highest phosphorous removal (70%) was
achieved by Scenedesmus species (obliquus and abundans) as compared
to 54% by Chl. sorokiniana species in the case of RW + ADW. TP concentration at the end of run (8.8 mg L−1) was below the discharge limit.
The TOC removal profiles of RW, ADW, RW + ADW, and Glucose + ADW for Chl. sorokiniana, Sc. obliquus, and Sc. abundans are
shown in Fig. 2d and described in the Supplementary file. VFAs were
mostly removed within initial three days by all three species for the
case of RW + ADW (Supplementary file). Similar findings were also
reported by Huo et al. (2018).
2.4. Analytical methods
BP, LP, and µmax were determined as per the equations used in a
previous study (Gupta and Pawar, 2018). The analytical instruments for
estimation of COD, total organic carbon (TOC), volatile fatty acids
(VFA), TN, total phosphorous (TP), and cell dry weight (CDW) are
mentioned in the Supplementary file. Bligh & Dyer method was used for
lipid extraction. The complete procedure of lipid determination is
mentioned in the Supplementary file. The procedure of estimating the
FAME is given in a previous study (Gupta and Pawar, 2018).
3. Results and discussion
3.1. Effect of different wastewaters or its combination on biomass growth
The biomass growth profiles of different microalgae species viz. Chl.
sorokiniana, Sc. obliquus, and Sc. abundans are shown in Fig. 1a, b, and c,
respectively. All three microalgae species showed the lag phase of two
days with RW only, most likely due to the adaptation period of these
species at high C/N ratio (16:1). On the other hand, these species directly showed log phase and grew exponentially till the fourth day and
then came to a stationary phase for the cases of ADW (C/N-0.37:1),
RW + ADW (C/N-3.25:1), and Glucose + ADW (C/N-3.48:1). Chl. sorokiniana species showed higher biomass concentrations of 710 ± 14
and 660 ± 13 mg L−1 for Glucose + ADW and RW + ADW, respectively as compared to 455 ± 8.8 and 370 ± 23.3 mg L−1 for ADW and
RW, respectively. The addition of RW and glucose as an organic carbon
source in ADW enhanced biomass growth by 1.45–1.56 times than ADW
alone. Similarly, the increments in biomass growth of Sc. obliquus for
RW + ADW
(695 ± 28.3 mg L−1)
and
Glucose + ADW
(795 ± 24.3 mg L−1) were 1.61 and 1.84 times higher than that with
ADW, respectively. Similar results were also observed with Sc. abundans. The maximum specific growth rates (µmax) were in the range of
0.5–0.63 day−1 for the cases of RW and ADW for all three microalgae
species as shown in Fig. 1d. However, the addition of RW and glucose in
ADW enhanced µmax, and it could reach 0.63–0.85 day−1 for all three
microalgae species. Overall, Sc. obliquus showed the highest biomass
concentrations and specific growth rates among the studied microalgae
species.
3.3. BP, yield (Y), lipid content, LP, and lipid composition
The BP, lipid content, and LP of different microalgae species Chl.
sorokiniana, Sc. obliquus, and Sc. abundans are shown in Table 1. The
BPs obtained with RW and ADW for all three microalgae species were in
the range of 79.9–99.2 mg L−1 d−1 and 87.5–111.6 mg L−1 d−1, respectively. The highest BP (211 ± 8.4 mg L−1 d−1) was obtained for
RW + ADW with Sc. obliquus which was 2.12 and 1.95 times higher
than RW and ADW, respectively. The present study also investigated
biomass yield, YCOD = biomass produced (mg L−1) per COD consumption (mg L−1), for three microalgae species. The YCOD was lower
(∼0.33 g g−1) for RW with all three microalgae species. The addition of
RW in ADW (RW + ADW) showed higher yields for Chl. sorokiniana
(0.6 g g−1), Sc. obliquus (0.6 g g−1), and Sc. abundans (0.5 g g−1) than
that obtained with RW solely for respective runs. However, the use of
Glucose + ADW as a substrate for microalgae growth showed relatively
higher yields with Sc. obliquus (0.73 g g−1), Chl. sorokiniana
(0.65 g g−1), and Sc. abundans (0.63 g g−1). The highest BP obtained for
RW + ADW with Sc. obliquus was 211 mg L−1 d−1 which is reasonably
good as compared to the BPs obtained with following species: Sc. bijuga
(50.75 mg L−1 d−1) cultivated in anaerobically digested food wastewater (Shin et al., 2015), Sc. obliquus (68.3 mg L−1 d−1) cultivated in
food wastewater (Ji et al., 2015), Chl. pyrenoidosa (375 mg L−1 d−1)
cultivated in mixed wastewaters (Tan et al., 2018), Chl. protothecoides
(290 mg L−1 d−1) cultivated in anaerobically treated brewery
3.2. COD, TOC, VFA, and nutrients (TN and TP) removals
The COD and TN removal profiles for Chl. sorokiniana, Sc. obliquus,
and Sc. abundans are shown in Fig. 2a, b, and c, respectively. The microalgae Chl. sorokiniana removed COD by 92 ± 1.7% (net reduction of
1105 mg L−1) from RW as compared to 32.8 ± 12% from ADW (net
reduction of 42 mg L−1) (Fig. 2a) in 8 days. However, the addition of
RW and glucose in ADW showed higher COD removals, 1104 ± 10.6
and 1089 ± 24 mg L−1 (∼85%), respectively with this species in total
8 days. Similarly, the COD removals by Sc. obliquus were 88.4 ± 2.47%
(1061 mg L−1) and 39.8 ± 13% (51 mg L−1) for RW and ADW, respectively (Fig. 2b). Furthermore, the addition of RW and glucose in
ADW
showed
higher
COD
removals,
1157 ± 32
and
1082 ± 35 mg L−1 (89 and 83.4%), respectively with Sc. obliquus.
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Bioresource Technology 269 (2018) 571–576
S. Gupta, S.B. Pawar
Fig. 2. Time course profiles of soluble COD, TN, TOC, and TP reductions by microalgae species cultivated on RW, ADW, RW + ADW, and Glucose + ADW, a) COD
and TN reduction by Chl. sorokiniana, b) COD and TN reduction by Sc. obliquus, c) COD and TN reduction by Sc. abundans, d) TOC and TP reductions by all microalgae
species. Similar superscript letters indicate no significant difference between groups RW, ADW, RW + ADW, and Glucose + ADW for respective species (p > 0.05).
wastewater (Darpito et al., 2015), and Sc. obliquus (156 mg L−1 d−1)
cultivated in brewery wastewater (Marchao et al., 2018).
The total lipid contents were 21.4–25.8% of CDW for RW and
20.1–23.1% of CDW for ADW with all three microalgae species
(Table 1). The LP obtained for RW with Chl. sorokiniana
(12.5 ± 1.4 mg L−1 d−1) was nearly similar to that obtained for ADW
(∼13 ± 0.2 mg L−1 d−1) with both Chl. sorokiniana and Sc. obliquus.
However, the addition of RW in ADW (RW + ADW) showed enhancement in total lipid contents which reached to 28.6–32.5% of CDW for
all three microalgae species. The maximum lipid content and productivity (32.5 ± 2.3% of CDW and 27.5 ± 1.2 mg L−1 d−1) obtained
for RW + ADW with Sc. obliquus. Furthermore, Glucose + ADW also
showed increased lipid content (26–28.8% of CDW) for all three microalgae species, and the highest lipid content and productivity
(28.8 ± 1.8% of CDW and 26.7 ± 2.3 mg L−1 d−1) were obtained
with Chl. sorokiniana. Results indicated that the presence of sufficient
organic carbon source could promote the assimilation of carbon and
increase lipid accumulation. Although the maximum biomass concentrations (700–795 mg L−1) obtained for Glucose + ADW for all
three species were significantly higher than that obtained with
RW + ADW (550–695 mg L−1) (p < 0.05), the lipid productivities
obtained with RW + ADW were significantly similar to that obtained
with Glucose + ADW. Hence, mixing of RW with ADW seems to be the
better option as compared to glucose addition because such combination would eliminate the need of extra carbon source and minimize the
extra cost of glucose as well as nutrients.
The lipid compositions of three microalgae species for different
combinations of experiments are also shown in Table 1. The fatty acid
C16:0 mainly accumulated in all three microalgae species which contributed as much as 25% of total fatty acids (TFA). The lipid composition of Chl. sorokiniana and Sc. obliquus cultivated in RW and ADW
showed major proportions of C16:0 and C18:3 which contributed
around 55% of TFA for each case. However, for runs on RW + ADW
and Glucose + ADW, the major fatty acids were C16:0, C16:1, C18:0,
and C18:1. The polyunsaturated fatty acid (PUFA) content of Chl. sorokiniana and Sc. obliquus significantly reduced for runs on RW + ADW
(10.5%) and Glucose + ADW (9.31–13.94%) as compared to that obtained for the runs on RW (36.69–46.75%) and ADW (46.15–53.43%)
individually (p < 0.05). The monounsaturated fatty acids (MUFA)
contents were more than 47% for RW + ADW and Glucose + ADW.
Hence, the addition of carbon supplement was found to alter the lipid
composition from rich PUFA to rich MUFA. Thus, it can be said that the
rich carbon and nitrogen media showed a reduction in PUFA contents
as compared to rich nitrogen and deficient carbon media. Moreover, it
is interesting to know that the C18:3 contents, which should be below
12% (w/w) of TFA to adhere to the standard quality of biodiesel (EN
14214), were not found within the acceptable limit for the runs with
sole RW or ADW by any of the studied species. However, the desired
limit was accomplished for the runs with RW + ADW and glucose + ADW by all three microalgae species. Thus, the selected strategy
(RW + ADW) of this study was proven to produce the biodiesel of desired proportions of saturated fatty acid (SFA) and MUFA along with
C18:3 content less than 12% (w/w).
574
575
152 ± 5.6b
29.0 ± 2.1
23.5 ± 0.6b
0.9 ± 0.3
18.15 ± 2.5
22.2 ± 2.1
19.0 ± 4.3
27.39 ± 3.9
9.92 ± 0.4
0.67 ± 0.2
1.8 ± 0.1
38.94 ± 8.9a
50.47 ± 8.2b
10.59 ± 0.7b
87.5 ± 9.4a
20.1 ± 0.6
13.1 ± 0.2a
2.2 ± 0.7
23.5 ± 1.4
4.33 ± 0.9
3.91 ± 0.9
4.03 ± 0.2
12.62 ± 3.8
40.81 ± 1.0
8.6 ± 1.5
36.00 ± 1.0a
10.56 ± 1.8a
53.43 ± .8a
0.37 ± 0.5
12.9 ± 2.9
23.22 ± 1.3
19.48 ± 0.2
29.71 ± 0.9
13.7 ± 0.6
0.23 ± 0.1
0.37 ± 0.5
32.76 ± 2.1a
53.30 ± 2.7b
13.94 ± 0.6b
164 ± 2.6b
28.8 ± 1.8
26.7 ± 2.3b
2.34 ± 0.7
29.8 ± 2.3
5.28 ± 0.7
5.59 ± 0.9
12.7 ± 1.0
11.8 ± 0.8
24.9 ± 2.7
7.6 ± 0.5
42.99 ± 0.8a
20.33 ± 1.1
36.69 ± 1.9
99.2 ± 3.5a
21.4 ± 2.2
9.04 ± 2.0a
3.26 ± 0.9
28.25 ± 1.3
5.72 ± 1.1
6.15 ± 1.5
1.97 ± 1.1
14.58 ± 1.4
31.57 ± 2.3
8.5 ± 0.4
42.89 ± 2.2a
10.95 ± 3.2
46.15 ± 0.9
108 ± 6.4a
22.0 ± 0.1
13.6 ± 0.9a
ADW
1.68 ± 0.2
21.2 ± 5.4
19.77 ± 1.0
20.39 ± 3.6
26.47 ± 2.7
10.5 ± 1.7
n.d.
n.d.
41.58 ± 1.8a
47.92 ± 3.5a
10.50 ± 1.7a
211 ± 8.4
32.5 ± 2.3
27.5 ± 1.2b
RW + ADW
n.d.
21.1 ± 1.1
18.9 ± 0.9
22.1 ± 0.8
28.6 ± 0.9
9.3 ± 2.2
n.d.
n.d.
43.2 ± 0.4a
47.5 ± 1.9a
9.3 ± 2.2a
244.3 ± 4.2
26.0 ± 1.1
25.5 ± 3.7b
Glucose + ADW
3.52 ± 0.6
34.05 ± 1.5
34.17 ± 1.3
6.36 ± 0.6
4.09 ± 0.7
4.88 ± 1.1
12.26 ± 1.4
0.68 ± 0.1
41.09 ± 0.9a
41.77 ± 1.2
17.14 ± 0.2
97.5 ± 8.2a
24.0 ± 1.5
7.7 ± 0.5a
RW
Sc. abundans
1.41 ± 0.5
32.63 ± 1.8
28.39 ± 2.5
5.78 ± 1.2
2.89 ± 0.2
7.77 ± 1.8
17.66 ± 1.6
3.47 ± 0.7
41.88 ± 1.1a
32.69 ± 3.3a
25.43 ± 3.5
111 ± 5.3a
23.1 ± 2.1
10.4 ± 1.2a
ADW
n.d.
46.24 ± 6.1
14.12 ± 1.5
15.17 ± 2.6
18.59 ± 1.2
5.88 ± 1.1
n.d.
n.d.
61.41 ± 1.4
32.71 ± 0.3a
5.88 ± 1.1a
165 ± 3.3
28.6 ± 2.5
20.2 ± 1.9b
RW + ADW
n.d.
60.71 ± 2.4
3.3 ± 0.2
11.26 ± 2.1
15.66 ± 0.4
9.07 ± 2.4
n.d.
n.d.
71.97 ± 0.3
18.96 ± 2.8
9.07 ± 2.4a
185 ± 9.5
27.7 ± 1.3
23.4 ± 0.9b
Glucose + ADW
n.d. – not detected.
SFA-saturated fatty acids; MUFA-monounsaturated fatty acids; PUFA-polyunsaturated fatty acids.
Similar superscript letters indicate no significant difference between groups RW, ADW, RW + ADW, and Glucose + ADW for respective species (p > 0.05).
One-way analysis of variance (ANOVA) was used for analysis of differences among different mean values followed by Tukey post hoc test. p < 0.05 level of confidence was considered as a significant difference in the
variables.
79.9 ± 2.2a
BP (mg L−1 d−1)
Lipid content (%)
25.8 ± 1.2
LP (mg L−1 d−1)
12.5 ± 1.4a
FAME Components (%)
C14:1
2.62 ± 0.2
C16:0
27.9 ± 2.1
C16:1
6.05 ± 0.1
C18:0
3.57 ± 1.1
C18:1
5.81 ± 0.2
C18:2
16.1 ± 3.1
C18:3
30.68 ± 1.5
C20:0
7.32 ± 1.3
SFA
38.76 ± 4.6a
MUFA
14.49 ± 0.2a
PUFA
46.75 ± 4.5a
Glucose + ADW
RW
RW + ADW
RW
ADW
Sc. obliquus
Chl. sorokiniana
Table 1
Lipid profiles of Chl. sorokiniana, Sc. obliquus, and Sc. abundans cultivated on raw wastewater (RW), anaerobically digested wastewater (ADW), RW + ADW, and Glucose + ADW. The values are expressed as mean ± SD
for n = 3.
S. Gupta, S.B. Pawar
Bioresource Technology 269 (2018) 571–576
Bioresource Technology 269 (2018) 571–576
S. Gupta, S.B. Pawar
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The addition of carbon-rich RW into carbon-deficient but nutrientrich ADW was a suitable solution for both in situ wastewater treatment
and biomass generation for biofuels. Total nitrogen from ADW was
removed well below the discharge limit (TN < 50 mg L–1) with the
given strategy within reasonable time. The extra added organic carbon
through RW was also reduced down below the discharge limit
(COD < 250 mg L–1). Moreover, in the case of bioenergy application,
microalgae cultivation on this industrial wastewater could reduce the
costs associated with carbon and nutrients without compromising lipid
productivity.
Acknowledgments
The corresponding author acknowledges the Department of Science
and Technology (DST), New Delhi for financial support for this research
work under the scheme of DST INSPIRE Faculty Award
(IFA13–ENG63). Ms. Suvidha Gupta is thankful to Council of Scientific
and Industrial Research (CSIR), New Delhi, India for providing Senior
Research Fellowship (SRF) to do her Ph.D.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in the
online version, at https://doi.org/10.1016/j.biortech.2018.08.113.
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