Biomedical Engineering Reference
In-Depth Information
Chapter 11
I
NTERACTION OF
C
R
(VI)
WITH
G
REEN
M
ICROALGAE
G
ROWTH
: A C
OMPARATIVE
S
TUDY
M. Alzira P. Dinis
1,a
, Vítor J.P. Vilar
2,b
,
Álvaro A.M.G. Monteiro
1,2,c
, Rui A.R. Boaventura
2,d
1
University Fernando Pessoa, Praça 9 de Abril, 349, 4249-004 Porto, Portugal
2
Laboratory of Separation and Reaction Engineering, Department of Chemical
Engineering, Faculty of Engineering, University of Porto,
Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
Abstract
Microalgae
Chlorella fusca
ACOI 621,
Chlorella vulgaris
ACOI 879,
Scenedesmus acutus
ACOI 538 and
Scenedesmus obliquus
ACOI 550, all native from Portugal, were characterized
in terms of specific growth rate. The effect of pH and the presence of Cr(VI) in concentrations
up to 25 mg l
-1
(50 mg l
-1
for
Chlorella fusca
) has been evaluated. The logistic equation of
population growth
(
)
(
)
= − +
adequately describes the cellular growth.
Experiments at pH = 6.5 and temperature around 24.5 ºC, in the absence of Cr(VI), led to
specific growth rates (μ) of 0.0370, 0.0284, 0.0359 and 0.0162 h
-1
and maximum biomass
concentrations
(
K
) of 403.3, 369.2, 542.9 and 604.1 mg l
-1
for
C. fusca
,
C. vulgaris
,
S. acutus
and
S. obliquus
, respectively. Experiments carried out with the same algae at approximately
21 ºC, also in the absence of Cr(VI), gave μ values of 0.0241, 0.0357, 0.0272 and 0.0289 h
-1
and
K
values of 292.6, 169.9, 263.1 and 327.8 mg l
-1
for initial pH = 6.5 and μ values of
0.0115, 0.0177, 0.0137 and 0.0158 h
-1
and
K
values of 35.9, 3.0, 32.8 and 54.7 mg l
-1
for
initial pH = 7.9. Higher pH results in a significantly lower growth rate and
C. vulgaris
seems
to be the less resistant microalgae to changes in the environmental conditions. Looking
simultaneously at μ and
K
values, the best performance in terms of growth kinetics was
obtained for
S. acutus
and
C. fusca.
Growth inhibition is visible for Cr(VI) ≥ 5 mg l
-1
but
concentrations up to 1 mg l
-1
seem not to seriously affect algal growth, even increasing the
C.
a
n
11
n
1
K
e
−
μ
t
1
K
0
E-mail address: madinis@ufp.edu.pentru; Tel.: +351-22-5081683; fax: +351-22-5081674 (Corresponding author:
M. Alzira P. Dinis).
b
E-mail address: bventura@fe.up.pt (Rui A.R. Boaventura).
c
E-mail address: vilar@fe.up.pt (Vítor J.P. Vilar).
d
E-mail address: aamont@ufp.edu.pt (Álvaro A.M.G. Monteiro).
