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A B S T R A C T
Microalgae are unicellular organisms, photosynthesizers that present
cell duplication exponentially and biosorption capacity of nutrients
dissolved in water. The objective of this work was to evaluate the capacity
of the microalga Pseudokirchneriella subcapitata for bioremediation of
metals and salts. In this aspect, the reduction of the metals and salts in
the synthetic effluents by the microalga P. subcapitata was evaluated:
(T1) culture medium (control); (T2) culture medium contaminated
with aluminum chloride; (T3) culture medium contaminated with
ferrous sulfate; (T4) culture medium contaminated with zinc sulfate;
(T5) culture medium contaminated with the combination of aluminum
chloride, ferrous sulfate and zinc sulfate. The bioremediation process
was evaluated by comparing culture media with suspended microalgae
to a filtrate version of the same medium. Iron and zinc metals, as
well as nitrogen and phosphorus salts, showed depleted values in
the filtered medium, indicating efficiency in the treatment of water
by microalgae. Aluminum content was below the limit of detection
in all treatments. The cumulative values in the microalgae biomass
were, in descending order: nitrogen, zinc, iron and phosphorus, thus
indicating the assimilation of the contaminants in the algal biomass.
In addition, high biomass production of the microalgae was observed.
The highest production rate was verified in the synthetic effluent with
the association of metals, indicating a synergy between contaminants,
which was probably responsible for reducing the toxic effect on the
microalgae. These results indicated high potential for bioremediation
by microalga P. subcapitata, besides the possibility of using algal
biomass for biotechnological applications.
Keywords: adsorption; biosorption; Chlorophyceae; contaminants.
R E S U M O
As microalgas são organismos unicelulares, fotossintetizadores, que
apresentam duplicação celular exponencial e capacidade de biossorção
de nutrientes dissolvidos na água. O objetivo deste trabalho foi avaliar
a capacidade de biorremediação de metais e sais pela microalga
Pseudokirchneriella subcapitata. Nesse aspecto, avaliou-se a redução
de metais e sais nos efluentes sintéticos pelas microalgas P. subcapitata:
(T1) meio de cultura (controle); (T2) meio de cultura contaminado com
cloreto de alumínio; (T3) meio de cultura contaminado com sulfato
ferroso; (T4) meio de cultura contaminado com sulfato de zinco; (T5)
meio de cultura contaminado com a combinação de cloreto de alumínio,
sulfato ferroso e sulfato de zinco. O processo de biorremediação foi
avaliado comparando o meio de cultura com microalgas em suspensão
e o mesmo meio filtrado. Metais de ferro e zinco, assim como sais de
nitrogênio e fósforo, apresentaram valores esgotados no meio filtrado,
indicando eficiência no tratamento da água por microalgas. O teor de
alumínio ficou abaixo do limite de detecção em todos os tratamentos.
Os valores acumulados na biomassa de microalgas, em ordem
decrescente, foram nitrogênio, zinco, ferro e fósforo, indicando assim
a assimilação dos contaminantes na biomassa de algas. Além disso, foi
observada alta produção de biomassa das microalgas. A maior taxa de
produção foi verificada no efluente sintético com a associação de metais,
indicando sinergia entre contaminantes, provavelmente responsável
pela redução do efeito tóxico nas microalgas. Esses resultados indicaram
alto potencial de biorremediação pela microalga P. subcapitata,
além da possibilidade de utilização de biomassa de microalgas para
aplicações biotecnológicas.
Palavras-chave: adsorção; biossorção; Chlorophyceae; contaminantes.
Metals bioremediation potential using Pseudokirchneriella subcapitata
Potencial de biorremediação de metais pela microalga Pseudokirchneriella subcapitata
Mônica Ansilago1 , Franciéli Ottonelli1 , Emerson Machado de Carvalho2
1Universidade Federal da Grande Dourados – Dourados (MS), Brazil.
2Universidade Federal do Sul da Bahia – Itabuna (BA), Brazil.
Received on: 06/12/2020. Accepted on: 10/20/2020
Correspondence address: Mônica Ansilago. Itahum Highway, s/n, CEP: 79804-970, Dourados (MS), Brazil – E-mail: monica_ansilago@hotmail.com.
Conflicts of interest: the authors declare that there are no conflicts of interest.
Funding: Fundação de Apoio ao Desenvolvimento do Ensino, Ciência e Tecnologia (FUNDECT).
Received on: 06/12/2020. Accepted on: 10/20/2020
https://doi.org/10.5327/Z21769478834
Revista Brasileira de Ciências Ambientais
Brazilian Journal of Environmental Sciences
This is an open access article distributed under the terms of the Creative Commons license.
Revista Brasileira de Ciências Ambientais
Brazilian Journal of Environmental Sciences
ISSN 2176-9478
Volume 56, Number 2, June 2021
http://orcid.org/0000-0002-7866-3619
http://orcid.org/0000-0003-4677-4282
http://orcid.org/0000-0002-4865-6784
mailto:monica_ansilago@hotmail.com
https://doi.org/10.5327/Z21769478834
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Ansilago, M. et al.
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RBCIAMB | v.56 | n.2 | Jun 2021 | 223-231 - ISSN 2176-9478
Introduction
Population growth and the development of new production
technologies generate continuous environmental impacts. In this
scenario, there is a possibility of increasing concentration of con-
taminants in wastewater, which would require adequate treatment
for these effluents (Mahapatra et al., 2014), with the goal of reduc-
ing environmental impacts. These contaminants may present a wide
variety of organic and inorganic materials, including toxic metals
that pose high risks to aquatic environments (Carvalho et al., 2012;
Zhang et al., 2016).
In order to reduce the amount of contaminants in wastewater,
conventional measures have been adopted, but these are often un-
sustainable from an environmental, economic and energetic point
of view. Thus, there is great interest in the use of microorganisms/
biological materials in effluent treatment processes, due to econom-
ic feasibility and low risk to the environment. The use of microor-
ganisms in bioremediation processes is considered a clean and sus-
tainable technology. In addition, this technique makes it possible to
recycle nutrients efficiently and add value to the biomass produced
(Ramachandra et al., 2013).
Microalgae have high applicability in the field of biotechnology,
due to the high rate of biomass production and higher growth tenden-
cy (two to ten times) in relation to terrestrial plants. Consequently, the
ability of these organisms to absorb solar energy increases the fixation
of CO
2 by their metabolism (Priyadarshani and Rath, 2012; Sathasiv-
am et al., 2019), and it can increase the production of carbohydrates,
proteins, amino acids, lipids and other compounds of interest in algal
biomass. Data from the literature suggests high efficiency in the use
of microalgae for the reduction of contaminants resulting to effluent
treatment. It is possible to observe representative values in the remov-
al of mineral salts (Leong et al., 2018; Mohammadi et al., 2018; Rid-
ley et al., 2018; Saavedra et al., 2018), metals (Peng et al., 2017; Saavedra
et al., 2018; Shen et al., 2018), pesticides (González et al., 2012), phar-
maceutical compounds (Escapa et al., 2017), oils (Ammar et al., 2018),
among others.
Microalgae have been noted for producing lipids (Abdelaziz et al.,
2014), proteins, carbohydrates, pigments and carotenoids (β-carotene,
lutein, chlorophyll, etc.), vitamins (A, B1, B6, folic acid, etc.), antiox-
idants (catalases, polyphenols, etc.) and other interesting molecules.
These bioactive compounds are essential inputs for the food, pharma-
ceutical and cosmetic industries. In addition, they are an energy source
(Priyadarshani and Rath, 2012) and present high market value due to
the low costs of the production process. In this strategy, it is possible
to use the organism for production of bioactive compounds and sur-
factants, for different uses in biofuels, biofertilizers, biopolymers, bio-
films, among many others (Carvalho et al., 2012; Schmitz et al., 2012;
Gouveia et al., 2016).
Some factors are important to regulate the kinetics growth of mi-
croalgae and contribute with high production of algal biomass; for
instance, the concentration of nutrients present in the medium, the
luminosity and the temperature (Carvalho et al., 2012; Wang et al.,
2014; Ansilago et al., 2016). Currently, one of the major obstacles in
the production of industrial scale microalgae lies in the high cost of
culture medium. An alternative culture medium that has been widely
used is chemical fertilizer based in nitrogen, phosphorus and potassi-
um (NPK), due to the high concentrations of micro and macronutri-
ents. Besides, it presents low cost, availability in the market and facility
in the preparation of culture medium (Sipaúba-Tavares et al., 2009;
Carvalho et al., 2012; Ansilago et al., 2016). In order for it to become
even more economically attractive, it is necessary to add value to the
cultivation process.
Different species of microalgae were used in wastewater treat-
ment processes. Leong et al. (2018) obtained results of removal of
up to 98% of nitrogen in domestic effluent using the microalga
Chlorella vulgaris. Saavedra et al. (2018) tested the removal of met-
als in effluent, obtaining efficiency in manganese (99.4%), arsenic
(40.7%), barium (38.6%), zinc (91.90) and copper (88%) removal,
using the microalgae C. vulgaris, Scendesmus almeriensis and Chlo-
rophyceae spp. The microalga C. vulgaris was also used for mercu-
ry bioremediation, obtaining removal values of 62.85 and 94.74%
(Peng et al., 2017).
The species Pseudokirchneriella subcapitata has been reported in
nutrient removal studies concerning elements such as nitrogen and
phosphorus (Gonçalves et al., 2016), as well as in toxicity studies on
media containing toxic metals (Gao et al., 2016; Sousa et al., 2018). It is
a half moon-shaped, single-celled green algae, with a single chloroplast
containing chlorophyll a and b (Granados et al., 2008). This microalga
has been used in biotechnological trials to evaluate its tolerance and
production under conditions of contamination by toxic metals (Lima,
2010; Carvalho et al., 2012). The data obtained is indicative of the po-
tential of P. subcapitata in the complementary treatment of domestic or
industrial wastewater.
Although the microalga P. subcapitata presents desirable charac-
teristics for wastewater bioremediation, experiments in controlled en-
vironments are still needed to evaluate its ability to remove nutrients of
water, whether salts and/or metals, as well as to evaluate the production
of algal biomass in liquid media substrates with the presence of con-
taminants. For this purpose, the objective of this study was to evaluate
the bioremediation capacity of metals and salts by P. subcapitata mi-
croalgae in laboratory culture.
Materials and Methods
The P. subcapitata inoculum was obtained from the Laboratory
of Algae Physiology at Universidade Federal de São Carlos (UFS-
Car), isolated from the Broa Dam (São Carlos, SP, Brazil). The mi-
croalga was cultured and maintained in standard medium CHU12
(Chu, 1942) in the laboratory of the Center for Biodiversity Re-
search (CPBio) at Universidade Estadual de Mato Grosso do Sul
Metals bioremediation potential using Pseudokirchneriella subcapitata
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(UEMS/Dourados, MS, Brazil). The cultivation system was static
nonaxenic, with constant aeration and room temperature (22 ±
2.0°C). The tests were maintained in a BOD incubator with photo-
period control of 2,500 LUX provided by white fluorescent lamps
(12 h light/ 12 h dark).
The culture medium of the microalgae was prepared by adding 1
mL of NPK stock solution to 1 liter of distilled water that was auto-
claved at 120°C for 20 minutes (e.g., Ansilago et al., 2016). The NPK
stock solution was prepared with 0.70 gL-1 of chemical fertilizer N:P:K
(20-5-20 gL-1), according to Sipaúba-Tavares and Rocha (1993) and
Carvalho et al. (2012). The rates of daily growth were obtained by
Equation 1:
(Nn-N1)/T (1)
Where:
Nn = the algal density value at the desired sample time (number of
microalgae cells);
N1 = the algal density value at the initial time of the experiment
(number of microalgae cells);
T = the desired sample time (days).
The elaboration of each treatment is described in Table 1. Treat-
ments were performed in triplicate. The value used from each contam-
inant was established based on the limit allowed by CONAMA’s Reso-
lution nº 357/2005 (Brasil, 2005), which was doubled.
For the metal analysis, 100 mL was collected from each Erlenmey-
er flask at the beginning of the test (day 1) and at the end of the test
(day 21). On day 1, the sample was collected before insertion of P. sub-
capitata. On the last day of the test, the samples were divided into two
equal fractions: one filtered (Whatman microfiber filter, chemically
inert, with porosity of 0.45 μM) and another unfiltered (Figure 1), in
order to get the Percentage of nutrient removal (% R) between suspen-
sion medium and filtered medium on day 21.
The analysis of metals (zinc, aluminum and iron) was determined
by flame atomic absorption spectrometry techniques, EAA-flame, ac-
cording to Welz and Sperling (1999). The total phosphorus analyzes
were read by visible ultraviolet spectroscopy, UV-VIS, according to
Soares et al. (2001). For the total nitrogen analyses, the Kjeldhal micro-
distillation technique was used, as described in Mantovani et al. (2005),
and then titrated by sodium hydroxide (NaOH); subsequently, the val-
ue consumed was converted to mg L-1 of mineral nitrogen, according
to Tedesco et al. (1995).
To evaluate the potential bioremediation in each treatment,
the concentration values of each nutrient (mg L-1) were compared
in the microalgae suspension samples and in the filtered samples.
For this, the percentage of removal was used through Equation 2:
6
The elaboration of each treatment is described in Table 1. Treatments were
performed in triplicate. The value used from each contaminant was established based on the
limit allowed by CONAMA’s Resolution nº 357/2005 (Brasil, 2005), which was doubled.
For the metal analysis, 100 mL was collected from each Erlenmeyer flask at the
beginning of the test (day 1) and at the end of the test (day 21). On day 1, the sample was
collected before insertion of P. subcapitata. On the last day of the test, the samples were
divided into two equal fractions: one filtered (Whatman microfiber filter, chemically inert,
with porosity of 0.45 μM) and another unfiltered (Figure 1), in order to get the Percentage of
nutrient removal (% R) between suspension medium and filtered medium on day 21.
The analysis of metals (zinc, aluminum and iron) was determined by flame atomic
absorption spectrometry techniques, EAA-flame, according to Welz and Sperling (1999). The
total phosphorus analyzes were read by visible ultraviolet spectroscopy, UV-VIS, according
to Soares et al. (2001). For the total nitrogen analyses, the Kjeldhal microdistillation
technique was used, as described in Mantovani et al. (2005), and then titrated by sodium
hydroxide (NaOH); subsequently, the value consumed was converted to mg L-1 of mineral
nitrogen, according to Tedesco et al. (1995).
To evaluate the potential bioremediation in each treatment, the concentration
values of each nutrient (mg L-1) were compared in the microalgae suspension samples and in
the filtered samples. For this, the percentage of removal was used through Equation 2:
(2)
Where:
C0 and Ce = the concentrations of nutrients in the liquid phase (mg L-1) on the 21st day, when
microalgae reach the stationary phase of growth, in the suspended material and in the filtrate
one, respectively. The data was evaluated via analysis of variance (ANOVA) and Tukey’s
test, in the statistical program GENES, version DOS and Visual Basic 5.0.
The chemical soil analysis manual of the Paraná Agronomic Institute (Pavan et al.,
1992) was used as methodology for the analyses. The laboratory analyses were performed in
the Laboratory of Environmental and Instrumental Chemistry at Universidade Estadual do
Oeste do Paraná (Unioeste), Marechal Cândido Rondon, PR, Brazil.
RESULTS AND DISCUSSION
(2)
Where:
C0 and Ce = the concentrations of nutrients in the liquid phase
(mg L-1) on the 21st day, when microalgae reach the stationary
phase of growth, in the suspended material and in the filtrate one, re-
spectively. The data was evaluated via analysis of variance (ANOVA)
and Tukey’s test, in the statistical program GENES, version DOS and
Visual Basic 5.0.
The chemical soil analysis manual of the Paraná Agronom-
ic Institute (Pavan et al., 1992) was used as methodology for the
analyses. The laboratory analyses were performed in the Labora-
tory of Environmental and Instrumental Chemistry at Universi-
dade Estadual do Oeste do Paraná (Unioeste), Marechal Cândido
Rondon, PR, Brazil.
Results and Discussion
To evaluate the bioremediation potential of the P. subcapitata mi-
croalgae, the capacities of production in the contaminated medium
and removal of contaminants were considered.
The daily growth rate of P. subcapitata indicated that the treat-
ment contaminated with aluminum, iron and zinc simultaneously
(T5) showed the best algal biomass doubling rate. In addition to the
control, this treatment was significantly superior to the other treat-
Table 1 – Composition of treatments used to evaluate microalgae bioremediation by P. subcapitata.
Treatments Adw NPK MPs
Contaminants
AlCl3 FeSO4 ZnSO4
T1 400 50 50 - - -
T2 400 50 50 0.32 - -
T3 400 50 50 - 0.32 -
T4 400 50 50 - - 0.6
T5 400 50 50 0.32 0.32 0.6
Adw: autoclaved distilled water (mL); NPK: cultivation medium with nitrogen, phosphorus and potassium 20-5-20 g L-1, respectively (mL); MPs:
inoculum with the microalgae P. subcapitata (mL); contaminants: synthetic effluent based on aluminum chloride (AlCl3), iron sulphate (FeSO4) and
zinc sulphate (ZnSO4) (g L
-1).
Ansilago, M. et al.
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ments in the final period of the experiment (21st day of experiment).
Treatments contaminated only with aluminum (T2), iron (T3) or
zinc (T5) showed significantly lower growth rates than control over
almost the entire experimental period (Table 2).
Table 2 also shows the analyses resulting from growth curves of
P. subcapitata. The analysis of the algal growth curves by the covari-
ance analysis indicated that there was no significant difference be-
tween the control and the treatment contaminated with aluminum,
iron and zinc simultaneously (T5), corroborating the observations
mentioned above. The exponential growth rate (K) indicated better
productivity for treatment contaminated simultaneously with the
metals and for control, while treatment with zinc contamination
presented poor performance. The specific growth rate (μmax) also
indicated satisfactory production values for control and treatment
contaminated with metals simultaneously, as well as treatment con-
taminated only with iron (T3).
Table 2 – Analysis of variance (ANOVA) of the daily growth rate of P. subcapitata microalgae (mean ± standard error) of (T1) culture
medium (control); (T2) culture medium contaminated with aluminum chloride; (T3) culture medium contaminated with ferrous sulfate;
(T4) culture medium contaminated with zinc sulfate; (T5) culture medium contaminated with the combination of aluminum chloride,
ferrous sulfate and zinc sulfate, in each sampling period, followed by analysis of covariance (Ancova), exponential growth rate (k) and
specific maximum growth (μmax) of the 21 days of experiment*.
Anova Treatments
F p T1 T2 T3 T4 T5
3nd 11.1 < 0.05 4.8 a ± 0.16 -3.4 c ± 0.83 -2.1 c ± 0.61 0.1 b ± 0.55 -2.2 c ± 0.52
6th 53.4 < 0.05 2.2 b ± 0.37 2.3 b ± 0.19 0.1 c ± 0.43 0.4 c ± 0.33 4.8 a ± 0.23
9th 13.5 < 0.05 6.0 a ± 0.16 1.9 b ± 0.1 1.1 b ± 0.54 -2.0 c ± 0.16 2.2 b ± 0.25
12th 43.4 < 0.05 3.2 ab ± 0.06 2.4 b ± 0.45 0.2 c ± 0.22 0.3 c ± 0.12 4.0 a ± 0.31
15th 48.0 < 0.05 3.0 a ± 0.47 0.3 c ± 0.38 1.2 bc ± 0.13 0.5 c ± 0.10 2.3 ab ± 0.09
18th 71.5 < 0.05 2.2 ab ± 0.35 2.3 ab ± 0.25 1.6 b ± 0.17 0.0 ± 0.19 3.3 a ± 0.20
21st 99.3 < 0.05 4.6 a ± 0.28 2.9 b ±0.009 1.4 c ± 0.25 1.0 c ± 0.04 5.3 a ± 0.19
Ancova 14.19 < 0.001 AB BC BC C A
k 0,19 0,13 0,10 0,051 0,24
μmax 0,91 0,69 0,89 0,50 0,90
*Analysis of variance at 95% confidence followed by Tukey’s test, represented by lowercase letters in comparison in the lines, where equal letters in-
dicate statistically equal means and different letters have statistically different means between them. Analysis of covariance in the algal growth curve
at 99% reliability, where upper case letters indicate statistically equal means, and different letters have statistically different means between them.
Figure 1 – Schematization of the methodology used for analysis of metals and salts present in microalgae in suspension and filtered culture medium.
FAAS: Flame Atomic Absorption Spectrometry; UV-VIS: ultraviolet-visible spectrophotometry.
Metals bioremediation potential using Pseudokirchneriella subcapitata
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It was verified, however, that the growth curves of the algal bio-
mass have an exponential behavior only for the medium without
contaminant (control) and for the medium contaminated with all
the metals simultaneously. It has been observed that all trace ele-
ments, even those with biological function, such as zinc, when in
higher concentrations, can cause toxicity to organisms. On the oth-
er hand, the treatment contaminated with aluminum, iron and zinc
(T5) presented the best production, superior even to the control
one. In this case, it is possible to observe an antagonistic dynamic,
in which the effect of zinc on the exposure of other chemicals, such
as iron and aluminum, resulted in the reduction of its toxic effect
to microalgae, bringing about effects different from those expected
for the action of contaminants alone, which result from synergistic,
potentiation, antagonistic and additive interactions (Mozeto and
Zagato, 2008).
Another important factor to be analysed in the production of
microalgae and in the process of contaminant bioremediation is
the monitoring of the pH of the culture medium. It is observed in
Figure 2 that zinc and iron contamination raised the pH of the cul-
ture medium. However, a pH buffering in the culture medium is
observed on the 3rd day of experiment. It is possible to verify the
extent to which microalgae absorbed nutrients from the medium,
carried out chemical reactions and excreted residues, tending to al-
ter its acid-base balance, which can be verified by pH fluctuation.
Carvalho et al. (2012) observed that the microalga P. subcapitata
had considerable growth in an acidic medium, even playing a role
in capping the medium.
The increase in density of the algal biomass increases the fixa-
tion of CO2 through photosynthesis, providing greater dissociation
of carbonate (CO2
-2) and bicarbonates (HCO2
-) ions, which induces
the removal of carbonic acid, and may even precipitate metals in the
form of carbonates, followed by the release of OH- ions for the neu-
tralization of the medium (Mota and Von Sperling, 2009; Gardner
et al., 2011). All these chemical reactions may explain the increase
and subsequent stabilization of pH in all treatments.
Table 3 presents the percentage of removal of metals and salts
during the process of biomass production of the microalgae P.
Figure 2 – Ionic potential of hydrogen in culture media used for
the production of P. subcapitata.
Table 3 – Percentage of nutrient removal (% R) between suspension medium and filtered medium on day 21 of experiment (mean ±
standard error).
Fe Al Zn N P
T1 39.7B ± 1,1 < LD -600.1C ± 98,1 78.9A ± 1.6 19.6ns ± 0.9
T2 -8.7C ± 18,7 < LD -433.3 C ± 38,5 21.9C ± 3,4 9.2ns ± 1,1
T3 75.3 A ± 3,4 < LD -183.3BC ± 67.3 6.9D ± 4.0 17.5ns ± 3.7
T4 -16.9C ± 18,7 < LD -46.6B ± 81.3 46.0B ± 1.6 12.8ns ± 4.3
T5 27.3B ± 6.9 < LD 88,9A ± 1,8 57.2B ± 0.9 13.4ns ± 3.8
P < 0.05 - < 0.05 < 0.05 0.25
F 84.10 - 11.41 121.50 1.59
T1: control – no contaminants; T2: treatment contaminated with aluminum; T3: treatment contaminated with iron; T4: treatment contaminated
with zinc; T5: treatment contaminated with aluminum + iron + zinc; < LD: elements that have an absorbance value below the detection limit.
The analysis of variance (p < 0.05) was performed, followed by Tukey’s test in comparison with the lines, where the same letters indicate statistically
equal means and different letters present statistically different means.
Ansilago, M. et al.
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subcapitata adsorbed or (bio)sorbed by microalgae. In the anal-
ysis of the iron content in the culture medium, values of remov-
al were significantly higher in treatment contaminated with iron
(T3), followed by control (T1) and treatment contaminated by all
metals simultaneously (T5). Thus, it is possible to infer that the
microalgae is able to adsorb or (bio)sorb iron from the medium,
even in high concentrations. The capture of metal ions involves
some biosorption mechanisms, which are based on ion exchange,
coordination, complexation, adsorption and chemical precipita-
tion (Silva et al., 2013).
The results of the aluminum analysis in the medium were be-
low the limit of detection in all treatments, rendering the biore-
Main microalgae used Objective Growing medium Main results Reference
Oocystis sp. Biomass production and
sulfate removal
Effluent from
power plant
Removal of up to 32% sulfate Mohammadi et al.
(2018)Chorella sp. Biomass production of 50 mg L-1
Scenedesmus intermedius
Adaptation and removal of
lindane
BG11
Resistance by rare mutations after
exposure period up to 40 mg L-1;
subsequent removal by up to 99%
of lindane
González et al. (2012)
Chlorella vulgaris
Simultaneous cultivation
with activated sludge for
bioremediation and lipid
production
Domestic effluent
Removal of up to 98% of
nitrogen;
lipid yield up to 130 mg L-1
Leong et al. (2018)
Chlorella vulgaris Absorption of arsenic,
boron, copper, manganese
and zinc from water by
different
green microalgae
Synthetic medium
based on the water
composition of the
Loa river (Chile).
Removal of 99.4% for manganese
Saavedra et al. (2018)
Scenedesmus almeriensis
40.7% for arsenic
38.6% for boron
Chlorophyceae spp.
91.9% for zinc
88% for copper
Chlorella vulgaris
Bioremediation of mercury
by mineralized microalgae
Blue green
medium (BG11)
contaminating
with mercury
Removal of mercury from 62.85%
to 94.74%
Peng et al. (2017)
Nannochloropsis oculata
Oil removal and Chemical
oxygen demand (COD)
Oil effluent
Removal up to 89% of oil and up
to 90% of COD
Ammar et al. (2018)
Isochrysis galbana
Removal of up to 82% of oil and
up to 83% of COD
Phaeodactylum tricornutum
Growth capacity in nitrate-
containing medium
Modified F/2
medium
Removal of up to 1700 mg L-1 of
nitrate in 100 L bioreactor
Ridley et al. (2018)
Chlorella sp.
Efficiency in removal of
cadmium
Immobilization
in pellets derived
from a complex
of the botanical
genus Eichhornia
Removal up to 92.45% cadmium Shen et al. (2018)
Chlorella sorokiniana
Response of microalgae
to high concentrations
of paracetamol (PC) and
salicylic acid (AS)
Mann and Myers
Medium
Removal up to 69% for PC and
up to 98% for AS
Escapa et al. (2017)
Table 4 – Compilation of studies in bioremediation using different microalgae.
Metals bioremediation potential using Pseudokirchneriella subcapitata
229
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mediation process inconclusive. However, it is possible that alu-
minum is able to associate with other elements present, making
the reading by the method adopted inefficient.
The percentage of zinc removal was effective only in the
treatment contaminated with all metals (T5), which showed a
reduction of almost 90%. Other treatments, including treatment
contaminated with only zinc (T4), had negative removal values.
Gao et al. (2016) observed, in their study with P. subcaptata, an
elevation of zinc, without toxic potential, in the microalgae with
greater exposure to phosphorus, due to potentially induced by
Zn–P complexation or precipitation inside the cell. Saavedra
et al. (2018) also observed removal of up to 91.9% for zinc in a
study carried out with microalgae of the class Chlorophyceae. Oth-
er studies indicate that dead algae biomass may be even more ef-
ficient at retaining and accumulating metal elements than living
cells and tissues (e.g., Cossich, 2000). This process occurs due to
the changes in the nature of the cell surface because of the absence
of active transport of the dead microalgae, causing better adsorp-
tion of metals efficiency by the algal biomass.
The removal of nitrogen in the culture medium was signifi-
cantly higher in the control (T1). The value of phosphorus remov-
al was also higher in the control, but it did not differ significantly
from the previous treatments. It was possible to observe that, in
treatments contaminated with metals, the biosorption or adsorp-
tion of salts of nitrogen and phosphorus was low. The maximum
reduction value recorded was 78.9% for nitrogen and 19.6% for
phosphorus, all in the control treatment. This fact may have re-
sulted from the Redfield ratio (C
106H118O45N16P), which means
that algae, on average, demand 16 times more nitrogen than phos-
phorus (Redfield, 1958; Sperling, 2001). In a study by Wang et al.
(2014), a reduction of up to 95% and 95.7% for phosphorus and
nitrogen, respectively, was observed in a wastewater treatment
system using the microalgae genera Chlorella and Micractinium.
Based on the results, it is possible to observe a complex re-
lationship between microalgae bioremediation processes and the
antagonistic and synergistic effects of the contaminants, with each
other and with the microalgae itself. However, it is important to
establish standards of control and monitoring for these contami-
nants in the effluent, so that it is possible to understand the me-
tabolism and the efficiency of this system. In Table 4, we present
a compilation of studies using different species of microalgae for
Contribution of authors:
Ansilago, M.: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review
& editing, Visualization, Project administration, Funding acquisition. Ottonelli, F.: Conceptualization, Methodology, Validation, Formal analysis, Investigation,
Resources, Data curation, Writing – original draft. Carvalho, E.M.: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data
curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration.
the specific purpose of culturing, adaptation and bioremediation
in media containing metals and other organic and inorganic com-
pounds that can be biosorbed. Through these studies, it can be
established that wherever there was insertion and/or presence of
stressors in the culture medium of the microalgae, positive results
were obtained for the removal of these contaminants and conse-
quent increase in the production of algal biomass. This corrobo-
rates the results obtained in the present study, since the treatment
contaminated with all metals (iron, aluminum and zinc) (T5) ob-
tained a higher rate of algal biomass duplication, which can indi-
cate synergy between the contaminants, thus reducing the toxic
effects.
Conclusion
The experimental results showed that the microalga P. sub-
capitata presented bioremediation capacity (either by adsorption
and/or biosorption) and algal biomass production. The contam-
inants with higher concentration indices in the culture medium
obtained a higher percentage of removal (N > Zn > Fe > P > Al). It
was also possible to observe that, on a bench scale, the microalgae
were able to develop in the presence of the toxic metals inserted
in the medium.
In addition, the highest production rate was verified in
the synthetic effluent with the association of metals, indicat-
ing possible synerg y between aluminum, iron and zinc, which
was probably responsible for reducing the toxic effect on the
microalgae, meaning biomass gain for further biotechnological
applications.
However, more detailed studies are needed to improve the
technique and the methodology used, requiring shorter test times
and the use of other contaminating metals for influence and tox-
icity analysis.
Acknowledgments
We appreciate the support of Universidade Federal da
Grande Dourados – UFGD. Likewise, we thank the Center for Re-
search of Biodiversity at Universidade Estadual de Mato Grosso
do Sul for allowing us to use their laboratories, as well as the Labo-
ratory of Environmental and Instrumental Chemistry at Universi-
dade Estadual do Oeste do Paraná – Unioeste, Marechal Cândido
Rondon, PR, Brazil, for carrying out the chemical analyses.
Ansilago, M. et al.
230
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