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Water Cleaning by Means of Microalgae in the Channels of Xochimilco, Mexico
Written By
Saúl Almanza Encarnación, María Guadalupe Figueroa Torres, María Jesús Ferrara Guerrero, Aída del Rosario Malpica Sánchez and José Roberto Angeles Vázquez
Submitted: 07 March 2022Reviewed: 28 March 2022Published: 27 May 2022
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The lake of Xochimilco, Mexico presents a high degree of chemical contamination, despite belonging to a Protected Natural Area and RAMSAR site, due to this, it was decided to evaluate the quality of its waters and propose solutions to its contamination. The objective of this work was to know the relationship that exists between the microalgae species associated with a dump that affects the site, coming from a Wastewater Treatment Plant and the physicochemical factors coupled with the development of bioassays. Water sampling was carried out in the site and adjacent areas to know the microalgae species and their cleaning role, in addition to laboratory bioassays to verify the results. There are 88 species of microalgae and their influence on water cleaning. In laboratory, it was confirmed that some algae species were purifiers of contamination by nutrients.
Universidad Autónoma Metropolitana-Unidad Xochimilco, Maestría en Ecología Aplicada, México
María Guadalupe Figueroa Torres
Universidad Autónoma Metropolitana-Unidad Xochimilco, México
María Jesús Ferrara Guerrero
Universidad Autónoma Metropolitana-Unidad Xochimilco, México
Aída del Rosario Malpica Sánchez
Universidad Autónoma Metropolitana-Unidad Xochimilco, México
José Roberto Angeles Vázquez
Universidad Autónoma Metropolitana-Unidad Xochimilco, México
*Address all correspondence to: saul20almanza@gmail.com
1. Introduction
Nowadays the majority of water bodies are with some degree of affectation, in Mexico City one of the main aquatic ecosystems are Xochimilco channels located in the political delegation of the same name, this zone have different appointments including that of Natural and Cultural Heritage of Humanity in 1987 by UNESCO, it was recognized as Protected Natural Area in 1992, also, is considered an ecological conservation area, it is part of the RAMSAR wetlands of global importance, and is cataloged as a GIAHS site [1].
Previously, Lake Xochimilco received water from various rivers and springs, which was mainly used for crop irrigation; besides being the habitat of native and migratory birds [2]; nevertheless, nowadays it is threatened by several problems, mainly by overexploitation of water and contamination by use of agrochemicals [3, 4].
Also, pollutant sources have been observed such as clandestine discharges of sewage from human settlements, and the deposit of solid waste [5]. Since the growth of the urban spot, there have been changes in the productive activities causing diverse problems in the area such as the excessive growth of introduced aquatic vegetation like water lilies. Water control structures have been affected in the area and it has been observed a decrease in the extension of the main and secondary channels. This has caused that in places with little or no movement of water, there is an increase in eutrophication levels and flooding during the rainy season [6].
Due to the above, the aquatic communities have been affected, one of these communities are the microalgae which, by having short life cycles, present changes in its structure and dynamics in short period of time. Also, microalgae have a great importance for Xochimilco channels, despite their small size and being unnoticed by most people, because they provide important environmental services, such as: CO2 capture, oxygen liberation from photosynthesis, natural cleaning of the water of the channels (deseutrophication), in addition to reduce the concentration of heavy metals, which are harmful to the ecosystem [7, 8, 9, 10, 11].
On the other hand, microalgae serve as food for other species present in water bodies, such as copepods, crustaceans, small fish, and some amphibians in juvenile stages, helping to the conservation of biodiversity. Also, can be used as biological indicators to monitor water quality [4].
Considering the above, the aim of this investigation was to know the role of microalgae in the purification of water from a Wastewater Treatment Plant, under field and laboratory conditions.
The lake system of Xochimilco is located south in Mexico City, surrounded by a mountainous area formed by the hills Xochitepec, Cantil and the volcanoes Teoca, Zompole and Teutli [12]. It is in the geographic coordinates 19° 00′ and 19° 20’ North Latitude; 99° 00′ and 99° 16’ West Latitude, with an approximate surface of 2657 ha, at an altitude between 2240 and 2500 m [13, 14, 15].
The climate is sub-humid temperate, with rains in summer and an average annual temperature varying between 8 and 18°C. The average rainfall is of 620 mm/year, the most abundant rains occur between the months of June and September and the minimum from December to February [16].
Among the most important channels are Cuemanco, Canal Nacional, Chalco, del Bordo, Apatlaco, San Sebastián, Apampilco, Texhuilo and Japón. Also, the main lagoons are Tlilac, del Toro, Huetzalin, Apampilco, Texhuilo and the Lake of conservation of flora and fauna of San Gregorio Atlapulco [17].
2.2 Field work
Sampling was carried out at the dump of water from Cerro de la Estrella wastewater treatment plant, located in the old channel of Cuemanco. The samples of microalgae were collected directly from the outlet of the dump water pipe, just at the drop and at the distances of 10, 20, 40 and 60 m (Figure 1).
Figure 1.
Study zone and sampling points map, based on Google earth, 2020.
For microalgae study two types of samples were taken, for the quantitative and qualitative analysis. For the first, samples were taken with the aim of a Van Dorn bottle, placed in 500 mL containers with lugol at 1% solution. For qualitative samples it was used a trawl net with a mesh opening of 54 μm, this samples were placed in amber jars of 30 mL and it was added formalin at 4%. In each sampling point it was recorded the pH, temperature, conductivity, depth, and turbidity. Also, were taken water samples of 100 mL to determine nutrients concentrations of NO2-, NO3-, NH4+, and PO43− in laboratory.
On the other hand, water samples with live organisms were stored for the isolation of three species for use in wastewater purification bioassays from the Cerro de la Estrella treatment plant.
2.3 Laboratory work
The sample review of microalgae was carried out in Phycology and Phyto-pharmacology laboratory from UAM Xochimilco, using a Zeiss optical microscope model Axiostar. Aliquots of 0.1 mL were taken and reviewed with the scanning technique [18], which consist on locate a starting point and make the revision in the form of “transects”, from each sample the necessary aliquots were revised until no new organism was observed.
For the isolation of microalgae different techniques were used, including capillary pipetting, seeding in agar plates, and reseeding in liquid medium.
The nutrients (NO2-, NO3-, NH4+, PO43−, TP, and TN) were evaluated using a multiparametric photometer HI 83200 [19]. Initial parameters were valuated, which were the different forms of inorganic nitrogen (NO2-, NO3-, and NH4+), phosphate as orthophosphate and heavy metals (Pb, Ni and Cu), using a multiparametric photometer HI 83200 and a spectrophotometer HACH 3900.
Bioassays of removal of nutrients and heavy metals were conducted, for which the isolated microalgae were used in the samples of treated wastewater from the Cerro de la Estrella treatment plant. To bioassays, manual agitation twice a day were given to avoid sedimentation of microalgae and water nutrients.
To provide the necessary amount of light, white light bulbs were used and controlled at intervals of 12 hours light and 12 hours dark with a timer clock.
2.4 Data analysis
In order to know the differences in the values of nutriment concentrations and parameters taken in situ in the sampling points located at different distances, were obtained a coefficient of variation, standard deviation, and arithmetic mean, using the program Excel 2013, in addition to a linear correlation analysis to know the interaction with the physicochemical parameters registered in field.
On the other hand, counts were made for 10 days and plotted to know the growth curve of each isolated microalgae.
Regarding bioassays, with the obtained values population growth graphs were made for each microalga; also, it was made a comparison between physicochemical parameters measured in each bioassay. In addition, this data was analyzed to observe the change in nutrient and heavy metal concentrations in each bioassay and evaluated the purification capacity of each microalga.
A total of 88 species belonging to five Divisions were found, being Bacillariophyta the most diverse Division with 35 species, followed by Chlorophyta Division with 27 species, while Euglenophyta, Cyanoprokaryota and Pyrrophyta Divisions had 16, 6, and 4 species respectively (Figure 2).
Figure 2.
Percentage of algae species by division found in the “Cerro de la Estrella” treatment plant dump.
The sampling point with the highest number of species was the one located at 20 meters away from the dump, presenting 56 species, while the sampling point with the lowest quantity of species was the one located directly under the dump with only 16 species observed (Figure 3).
Figure 3.
Total number of species in the sampling points.
3.2 Physicochemical parameters
The values of the physicochemical parameters taken in the field and the nutrients of the samples analyzed in the laboratory are shown in Table 1. It is included the coefficient of variation, which showed that physicochemical parameters showed a low proportion of variation in most of them (2–18%), except in depth where it was obtained 37%. On the other hand, the nutrients also showed a low variation ranging from 14 to 20%.
Turbidity (cm)
Depth (cm)
Temperature (°C)
Conductivity (μS/cm)
pH
TN (mg/L)
TP (mg/L)
Direct
ND
ND
21.5
711
8.3
14.6
7.6
Fall
70
70
21.7
772
8
11.5
9.4
10 m
70
150
21.6
772
7.8
11.1
7.3
20 m
85
95
21.8
775
8
10.3
6.4
40 m
72
92
22.1
784
7.9
10.4
6.9
60 m
50
60
22.5
787
7.7
11
5
Standard deviation
12.52
34.90
0.37
28.07
0.21
1.60
1.50
Arithmetic mean
69.4
93.4
21.87
766.83
7.95
11.48
7.1
Variation coefficient
0.18
0.37
0.02
0.04
0.03
0.14
0.20
VC expressed in percentage
18%
37%
2%
4%
3%
14%
20%
Table 1.
Values of environmental factors (physical and chemical) in the Cerro de la Estrella treatment plant dump and in the different sampling points (at different distances).
The nutriments are shown as total nitrogen (TN) and total phosphorus (TP). Variation coefficient (VC) is expressed as the ratio between the standard deviation and the arithmetic mean.
The concentrations of NO2− were found at an interval between 0.621 mg/L obtained at 20 meters and 0.751 mg/L in the sample taken directly under the dump; for NO3− the concentrations interval was between 6.9 mg/L in the sampling point of 20 m, and 14 mg/L registered in the sample taken directly under the dump; moreover, the lowest concentration of NH4+ was found in the sample taken directly under the dump with 0.0129 mg/L and the highest value was obtained in the sample of the spot 20 m with 0.0174 mg/L, observing that the water from the dump, was enriched by mixing with the water of the ecosystem, which is more rich in this compound in the further sampling points. The concentrations of ortho PO43−were between 5.4 and 7.1 mg/L, having the lowest value in the sample from 40 m and the highest in the sample from 10 m (Figure 4).
Figure 4.
(a-d). Nutrient concentrations (NO2−, NO3−, NH4+ y PO43−) at the different sampling points.
Regarding the linear correlation analysis, it can be observed that NO2−, NO3− and NH4+ have a higher correlation value compared to the parameters measured in field, this in Ref. to species richness, instead in terms of abundance it is observed that NO2− and NH4+ together with turbidity are those that have a higher correlation, nevertheless, the correlation was lower when comparing it to the one obtained with species richness (Table 2).
Parameter
Species richness correlation
Abundance correlation
NO2−
0.7584
0.6497
NO3−
0.8485
0.5187
NH4+
0.9059
0.7887
PO4−3
0.0009
0.0704
Temperature (°C)
0.1295
0.00001
Conductivity (μS/cm)
0.6184
0.3647
pH
0.4663
0.0848
Turbidity (cm)
0.6920
0.7997
Depth (cm)
0.4803
0.4484
Table 2.
Linear correlation analysis of the physicochemical parameters on the richness and abundance of the species.
3.3 Isolation and growth of microalgae
As a result of the isolation methods (capillary pipetting and seeding in agar plates), it was possible to achieve the growth of three species of microalgae, two belonging to the Division Chlorophyta (Chlamydomonas sp. and Chlorella sp.) and one of the Division Bacillariophyta (Nitzschia cf. amphibia).
3.3.1 Growth curves
For the growth of isolated microalgae, the three strains were seeded in enriched liquid culture medium, based in the Bold Basal formula and cell counting were made for 10 days, having as a result the following:
Chlamydomonas sp.
In the following graph it is shown the growth behavior of microalga Chlamydomonas sp. in liquid culture medium presenting a maximum growth at ten days (Figure 5).
Figure 5.
Growth curve of Chlamydomonas sp.
Chlorella sp.
Regarding Chlorella sp. it was observed that its growth was exponential even after 14 days (Figure 6).
Figure 6.
Growth curve of chlorella sp.
Nitzschia cf. amphibia.
This microalga presented a heterogeneous growth in time, having its maximum growth point at thirteen days and then decrease (Figure 7).
Figure 7.
Growth curve of Nitzschia cf. amphibia.
3.4 Bioassays
3.4.1 Growth curves
As for the growth of microalga Chlamydomonas sp., it can be observed that there was an exponential increase of organisms during the first five days with a slight decrease at day six, recovering on the seventh day and from there presented marked fluctuations in the number of individuals until the end of the experiment. In the case of Chlorella sp. it was observed the same behavior as Chlamydomonas sp. because the maximum growth was reached at day five, presenting a decrease of organisms from day six until day ten, nevertheless, at day eleven there was an upturn of organisms maintaining it during three more days, to have a downbeat in the last two days.
On the other hand, the growth of Nitzschia cf. amphibia had an exponential growth in the first four days and a decease during the next two days, at seventh and eighth day it presented an upturn and then continue with ups and downs until the end of experiment (Figure 8).
Figure 8.
Growth curves of the three microalgae in the bioassays.
3.4.2 Nutriments and heavy metals comparison between treatments
The concentrations of NO2− in water of bioassay were higher after incubation time, as opposed to expected, however this could be since not being an axenic culture it could present nitrifying bacteria that can oxidate NH4+, increasing the NO2− at the end of incubation (Figure 9).
Figure 9.
Nitrites values of each treatment.
In the case of NO3-, it was observed that in treatments with Chlamydomonas sp. and Chlorella sp. there was a decrease in the quantities of this nutriment, contraire to the bioassays with Nitzschia cf. amphibia where its values increased after three days (Figure 10).
Figure 10.
Nitrates values of each treatment.
Moreover, in NH4+ there was a decrease of this nutriment with the three microalgae from day three to the end of the experiment (Figure 11).
Figure 11.
Ammonium values of each treatment.
Regarding phosphate it did not show a continuous decrease in any of the treatments with the three microalgae, so there were ups and downs over the course of the days in all treatments, nevertheless, Chlamydomonas sp. and Nitzschia cf. amphibia presented the lowest quantities of this nutriment at day 12 (Figure 12).
Figure 12.
Phosphates values of each treatment.
As regards heavy metals, in the case of copper a graph is not included because the values obtained were zero from the beginning of the experiment in the three treatments.
For nickel, it is noted that the quantities of this metal were not completely reduced, instead there were sharp fluctuations in values especially in Chlorella sp. and Nitzschia cf. amphibia, only in the bioassay with Chlamydomonas sp. it was observed a decrease of the metal from day nine (Figure 13).
Figure 13.
Nickel values of each treatment.
In the case of lead treatments, it was observed that the three species of microalgae decreased the quantities of this metal, however, the bioassay with Chlamydomonas sp., was the one that obtained the lowest concentration of lead at the end of the 15 days of experimentation (Figure 14).
Figure 14.
Lead values of each treatment.
Table 3 shows the removal percentage of each nutrient by the three microalgae in the different bioassays. Negative numbers indicate that there was no nutrient removal, but that its value increased.
Treatment
Day 0
Day 3
Day 6
Day 9
Day 12
Day 15
Nitrite
Chlamydomonas sp.
0
−34
−38
−84
−166
−141
Chlorella sp.
0
−41
−41
−50
−97
−147
Nitzschia cf. amphibia
0
−34
−53
−191
−269
−553
Nitrate
Chlamydomonas sp.
0
28
29
45
49
61
Chlorella sp.
0
33
40
55
53
57
Nitzschia cf. amphibia
0
58
30
15
−46
−28
Ammonium
Chlamydomonas sp.
0
99
100
99.5
98
98
Chlorella sp.
0
98
100
99
95
97
Nitzschia cf. amphibia
0
92
95
96
97
95
Phosphate
Chlamydomonas sp.
0
−302
−12
15
52
−157
Chlorella sp.
0
−286
26
−157
−144
1
Nitzschia cf. amphibia
0
−644
−212
12
36
−538
Nickel
Chlamydomonas sp.
0
0
−25
−13
50
75
Chlorella sp.
0
−50
38
13
0
−113
Nitzschia cf. amphibia
0
13
63
38
0
25
Lead
Chlamydomonas sp.
0
34
45
64
73
79
Chlorella sp.
0
37
58
55
61
64
Nitzschia cf. amphibia
0
2
45
49
47
48
Table 3.
Percentage of removal of each compound with each microalga.
According to obtained results a total of 88 species of microalgae were determined, from which 55 have been previously reported by diverse authors, in different points in the Xochimilco channels and at different seasons. On the other hand, 24 species were new registers for the study zone, which indicates that nowadays there’s no full knowledge of the species present in this place, this can be due to the fact that over time the conditions of the environment are changing, making changes in the microalgae community composition, as well as the introduction of new species, that come from treated water.
4.2 Physicochemical parameters
Regarding the parameters taken on field, it could be observed that most of them did not vary significantly, only depth had a variance higher than 30%, which decrease according to distance, one of the reasons can be the movement that the waterfall generates on the lake, because the greater the distance the movement of the water is less, which favors a higher deposit of sediments.
Nutriments values were compared with the NOM-001-ECOL-1996 [20], where the maximum permissible limits for basic pollutants in wastewater discharges are established. It was observed that the values of total nitrogen (TN) for use for agricultural irrigation do not exceed the maximum permitted limits (40–60 mg/L), because in the present investigation a maximum value of 14.6 mg/L was obtained. Nevertheless, this value is near the maximum limits permitted for urban public use which is of 15 mg/L.
Regarding to obtained total phosphorus values (TP), the values were in a range of 5 to 9.4 mg/L and they did not exceed the maximum permitted limits for use for agricultural irrigation which are of 20 mg/L daily average and 30 mg/L monthly. However, for urban public use, the obtained values are above the monthly average (5 mg/L) and very close to the permitted daily average which is of 10 mg/L [20].
As for nitrogen, it was observed a higher concentration in the form of Nitratos (NO3−) in the site of the dump (14 mg/L), observing a decrease as the sites were farther away from the waterfall, this can be due to the higher density of microalgae found in those sites, which could be using this nutrient, because NO3− are one of the main forms of nitrogen that absorb microalgae [21].
The above is complemented with the linear correlation analysis because the higher correlation values were obtained in the NO3− and NH4+ on species richness, which points out that the presence of these nutrients is essential for the growth and formation of biomass, as microalgae absorb them directly [22].
4.3 Isolation and growth of microalgae
After work with isolation techniques, the species Chlamydomonas sp. and Chlorella sp., responded better to isolation in liquid medium, because both species are more of planktonic character, in addition to being species with wide ranges of tolerance regarding temperature and nutriments.
Nitzschia cf. ampphibia being a specie of benthic character, was isolated in solid medium with the Pasteur pipette spraying technique, so when growing it produced brown spots, which is a characteristic of the species of Bacillariophyta Division.
It should be mentioned that the species Chlamydomonas sp. and Nitzschia cf. amphibia did not were very abundant in in reviewing field samples, only Chlorella sp. was.
4.4 Bioassays
4.4.1 Growth curves
Regarding the growth of the three microalgae in the wastewater from the dump, it was observed that none of them presented a normal growth curve [23], in such a way that in the case of Chlamydomonas sp. and Chlorella sp. they had an exponential growth until the fifth day of experiment without having a stationary phase, but continued directly to death phase during the sixth day for Chlamydomonas sp. and tenth day for Chlorella sp., to then observe ups and downs in the number of cells until the end of the experiment. These results differ from the study conducted by [24] which worked with Chlorella sp. and obtained a more normal growth curve, and it was observed that the maximum growth value was obtained at 15 says, having its death phase between 17 and 18 days of their experimentation.
Nitzschia cf. amphibia also showed a different growth than conventional curves, because it had an exponential growth during the firsts days having its maximum growth on day four without having an stationary phase, but as in the other two species went directly to the death phase during the five and six days of the experiment, followed by various phases of exponential growth and death in few days, which could be explained due to the rapid growth that is given by this species, that according to Brennan and Owende [25], some species of microalgae can duplicate its biomass in less than 24 hours.
Additionally, it was observed that in some time the cells remained glued to the glass in the flask and despite the care a smaller number of cells was counted. When the flask was vigorously agitated it was not counted the same number of individuals as the days before.
4.4.2 Comparison between treatments
Regarding to comparison of the nutriment evaluation it was observed that Chlamydomonas sp. and Chlorella sp. use NO3- and NH4+ as source of nitrogen because they reduced the NO3− in 61% for Chlamydomonas sp. and 57% for Chlorella sp. at the end of the experiment, and both species reduced up to 100% the NH4+ at day six, in this regard. Oliveros and Wild [26] point out that Chlorella sp. was capable of removing up to 95% of NO3− in wastewater and mentioned that this microalga is suitable for this type of treatment because it has a great ability to remove nutrients in wastewater. Meanwhile, Chacón et al. [27], mentioned in their study that the highest reductions by Chlorella sp. were of NH4+, reducing it by 100% as in this study. However, their experimentation time was 27 days while in this investigation was 15 days.
In the case of Nitzschia cf. amphibia, it was observed that this specie use NH4+ as source of nitrogen, because it reduced this nutriment in a 97% at 12 days of experimentation and according to Pérez [28], some microalgae prefer nitrogen in form of NH4+, so when looking at the graphs of the nitrite and nitrate values an increase was noticed instead of decreasing.
On the other hand, in the case of phosphates, the method of using it was more dynamic, which was reflected in increases and decreases during the experiment by the three microalgae, so a removal of this nutriment could not be found. However, it was observed that Nitzschia cf. amphibia and Chlamydomonas sp., presented higher percentages of removal of this nutriment at 12 days of experimentation with 36% and 52% respectively. This is like the reported by Oliveros and Wild [26], which worked with Chlorella sp. and obtained a removal percentage of 20% at 8 and 12 hours of experimentation.
About heavy metals, as mentioned above the values of copper were zero, so they were discarded from the subsequent analyses. Meanwhile, the levels of nickel were reduced by Nitzschia cf. amphibia, after six days of experimentation by 63%. Nevertheless, after that time the values increased again, which might suggest that microalgae adsorb and retain it for some time, but when it dies, the metal is released again, and the value increase. Instead, Chlamydomonas sp. had a slight increase in the values on the first six days; however, from day nine it reduced the value of nickel by 75% at the end of experiment, being this specie that show the highest removal percentage of removal. On the other hand, Chlorella sp. at the third day of experimentation had an increase in nickel values, and at sixth day there was a slight decrease of 63%, nevertheless, after that it was observed that the values increased util the end of the experiment, contraire to the experiment made by Hammouda et al. [29] which reported a removal of 77.3% up to 81% of Ni by Chlorella sp.
The lead was the metal that presented highest removal by the three microalgae, with 49% by Nitzschia cf. amphibia, 64% with Chlorella sp. and 79% with Chlamydomonas sp., being this last one the one with the highest capacity of absorption of this metal. It is worth mentioning that the experiment lasted 15 days and it was not possible to decrease the totality of this metal by the microalgae. Perhaps, if the experimentation time was longer, the totality of this metal could have been removed, but would be necessary to remove the produced biomass, because the metal would remain in the microalgae and could be transferred to the next food chain levels, including reaching humans.
Of the three microalgae study, Chlamydomonas sp. appears to be the one that have better capacity of nutrients and heavy metals removal with 50%, except in NO2-, so it is reiterated that apparently, they do not use this form of nitrogen for their growth. Secondly, there is Chlorella sp. which although with some nutrients such as phosphate had a low percentage of removal (26%), in other nutrients such as NH4+ reached to remove from 95 to 100% throughout the experiment. This match with what was reported by Martínez et al. [30], which mention that some species of chlorophytes are capable of remove 98% of the phosphorus and up to 100% of nitrogen in wastewaters.
Meanwhile, Nitzschia cf. amphibia resulted being the microalgae with lowest efficiency regarding the quantity of removed compounds, because of not decreasing nitrite and nitrate values and had low removal of heavy metals, nevertheless, it can be considered as highly efficient in the removal of NH4+ since it reached a 97%.
The algal community was composed by a total of 88 species from the Divisions Bacillariophyta, Chlorophyta, Euglenophyta, Cyanoprocaryota and Pyrrophyta.
24 new records were found for the study area.
Physicochemical parameters taken on field did not vary significantly over the sampling points.
NO3- and NH4+ are the parameters that had highest relation with species richness.
Valued nutriments in laboratory did not surpass the maximum permissible limits.
The spraying and seeding techniques in agar were the most effective for the isolation of microalgae species.
Chlorella sp. was the microalgae that best developed to the conditions of cultivation and the one that presented the greatest population growth.
Chlorella sp. was the specie that had better growth in the treatments.
Chlamydomonas sp. was the specie that presented highest percentages of nutrients and heavy metals removal.
Regarding nutrients, the three species presented good efficiency in the removal of NH4+.
Regarding heavy metals, the three species were efficient in the removal of lead.
It is recommended for future laboratory experiments, to work with axenic microalgal cultures, even though in natural conditions, microalgae coexist with bacteria.
We would like to express our gratitude to Universidad Autónoma Metropolitana and specially to Maestría en Ecología Aplicada for support to make the present research.
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Written By
Saúl Almanza Encarnación, María Guadalupe Figueroa Torres, María Jesús Ferrara Guerrero, Aída del Rosario Malpica Sánchez and José Roberto Angeles Vázquez
Submitted: 07 March 2022Reviewed: 28 March 2022Published: 27 May 2022
Open access peer-reviewed chapter
