- Email: [email protected]
Degradation of microalgae from freshwater by UV radiation
G Model JIEC 3236 No. of Pages 4
Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Journal of Industrial and Engineering Chemistry journal homepage: www.elsevier.com/locate/jiec
Short communication
Degradation of microalgae from freshwater by UV radiation M.M. Barrado-Morenoa,* , J. Beltrán-Herediaa,1, J. Martín-Gallardob a b
Department of Chemical Engineering and Physical Chemistry, University of Extremadura, Avda. De Elvas, s/n, 06071 Badajoz, Spain Department of Plant Biology, Ecology and Earth Science, University of Extremadura, Avda. De Elvas, s/n, 06071 Badajoz, Spain
A R T I C L E I N F O
Article history: Received 19 January 2016 Received in revised form 30 May 2016 Accepted 26 December 2016 Available online xxx Keywords: Algae Freshwater Photodegradation UV radiation
A B S T R A C T
Algae (Chlorella,Microcystis, Oocystis and Scenedesmus) degradation by ultraviolet radiation has been investigated. The radiation source was a low pressure mercury vapor lamp which emits monochromatic radiation at 254 nm. Experiments include initial algae concentration variation. After a period of exposure to UV radiation, algal mass concentration was reduced by more than 80%. The results were interpreted under Line Source Spherical Emission model, so quantum yield was the appropriate target variable for explaining the process. Global quantum yields are determined for Chlorella, Microcystis, Oocystis and Scenedesmus being 7.75 104, 3.65 105, 2.28 105, 1.74 104 mg E1, respectively. © 2016 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.
Introduction Eutrophication is the enhancement of the natural process of biological production in rivers, lakes and reservoirs, caused by increases in levels of nutrients, usually phosphorus and nitrogen compounds [1]. Eutrophication was recognized as a pollution problem in many western European and North American lakes and reservoirs in the middle of the twentieth century [2]. At the present, eutrophication causes a number of deleterious effects on drinking water treatment: reduction of coagulation efficiency resulting in a rising coagulant demand [3,4], increased membrane fouling [5], filter clogging, higher yield of sludge as a result of an increased coagulant dose [6] and disinfection by-product formation [7]. In addition, algae organic matters affect the color, taste and odor of drinking water and a number of cyanobacterial species also excrete toxic metabolites which can cause health problems [8]. For these reasons, it is necessary to eliminate algae from drinking waters; suitable techniques are coagulation [9,10], flotation [11], filtration [12], ozonation [13], chlorination [3], oxidation by potassium permanganate [14], electrochemical [15] and ultrasound [16] treatments. Previous studies have shown that ultraviolet radiation (UV), especially the shortwave ultraviolet (UV-C at 254 nm) is highly effective for the removal of algae [17,18]. UV radiation degrades to the
* Corresponding author. E-mail addresses: [email protected], [email protected] (M.M. Barrado-Moreno), [email protected] (J. Beltrán-Heredia), [email protected] (J. Martín-Gallardo). 1 Fax: +34 924289385.
target DNA much more efficiently than chemical agents in water. Moreover, this generates no chemical waste in its germicide effects and produces comparably lower disinfection by products. Studies have bring to light that ultraviolet radiation at 254 nm is an alternative to inhibit blooms of cyanobacterias and green algae in lakes and reservoirs [19]. For these reasons, in this paper is studied the degradation of Chlorella, Microcystis, Oocystis and Scenedesmus algae by UV radiation. Materials and methods Reagents The trials were carried out with water from a creek (AEMET) in Badajoz (Southwestern of Spain, Extremadura Community). The basic characteristics [20] of these waters are shown in Table 1. Algae cultures were incubated at 25 C under white light photoperiod of 12:12 in a culture medium supplied by Fluka (Algae culture broth). Chlorella, Microcystis, Oocystis and Scenedesmus inoculums were provided by the Department of Botany, University of Coimbra (Portugal). Photochemical trials The assays were carried out in an installation previously described [21]. Figure drawing thereof is shown in Fig. 1. Algae inactivation was carried out as follows: 500 mL of a solution of algal mass concentration for each test is prepared. The exact concentration of algae is determined by measuring the
http://dx.doi.org/10.1016/j.jiec.2016.12.030 1226-086X/© 2016 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.
Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030
G Model JIEC 3236 No. of Pages 4
2
M.M. Barrado-Moreno et al. / Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
Table 1 Raw water characterization data. Parameter
Units
AEMET
pH Conductivity Turbidity Total solids KMnO4 oxidability Hardness
–
8.18 0.3 351 2 10.75 0.3 2.65 0.2 6.96 0.3 212 3
mS cm1 NTU g L1 mg O2 L1 mg CaCO3 L1
fluorescence of chlorophyll in a fluorimeter (Aquafluor) previously calibrated [22]. This solution was introduced in the photochemical reactor. The UV lamp was turned on, and samples (5 mL) were collected at regular time. The experiment usually lasted for 30 min. Actinometric reactions permit to characterize of the lamp emissivity. Uranyl oxalate was extensively considered as a reference according to the general method [23]. Uranyl sulfate (UO2SO43.5H2O) was supplied from Panreac, while oxalic acid (C2H2O4) and potassium permanganate (KMnO4) were purchased by Sigma Aldrich. Results and discussion Algae degradation tests were performed to obtain information about their efficiency in process of UV radiation. At first, viability of this photodegradation process was confirmed by evaluating the apparent decay in algae content. Finally, kinetic model was utilized to model the process of algae degradation. Algae degradation Algae degradation was tackled through three trial series in which initial algae concentration was 25, 50 and 75 mg L1. As it can be appraised in Fig. 2 Scenedesmus is less responsive than the other algae to UV radiation because Chlorella, Microcystis and Oocystis concentration are negligible after being subjected to 30 min of light exposure. This may be due to the size and structure of microalgae; Scenedesmus is larger and more robust than the other algae.
This is to verify the feasibility of this procedure in degrading this type of microalgae although it does not provide valuable information in terms of reaction rate; therefore does not allow the comparison under different experimental conditions. Kinetic studies It is labeled to identify a target variable that represents the reaction rate and effectiveness of the degradation process in a numerical way. For this purpose, classical studies implement the Line Source Spherical Emission (LSSE) model [24] and they are still in force [25]. In short, the basis of LSSE model is shown in previous publications [21]. Following the model described is obtained the value of total radiation flow emitted by the lamp, WL, for the current system was 2.80 106 E s1. Molar extinction coefficients values were determined for each alga: Chlorella: 2.50 103; Microcystis: 3.77 104; Oocystis: 3.18 104; Scenedesmus: 4.52 103 (mg 1 cm1 L). According to the model algae degradation can be represented by Eq. (1). Z f t Wabs dt ð1Þ CB ¼ CB0 V 0 Where CB0 and CB are the concentration of chlorophyll at the start and at any one time. V is the total volume of the liquid phase (L) and Wabs is the flow of radiant energy absorbed by the reaction medium (Eins s1). Therefore it is possible to determine, for each operation time, the corresponding m, Wabs and integral term in Eq. (1). The linear adjustment of this expression will lead to a constant slope that is representative of f. This f (chlorophyll degraded by photons absorbed) is the kinetic parameter (called quantum yield) which allows us to compare different efficiencies at various operating conditions, hence, it can determine how the system responds to operational changes and, finally, to propose a theoretical or empirical model. In Fig. 3 it can be observed the graphical representations of these linear adjustments. Values quantum yields obtained are shown in Table 2. It can be seen that the quantum yields for each
Fig. 1. UV installation.
Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030
G Model JIEC 3236 No. of Pages 4
M.M. Barrado-Moreno et al. / Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
A
3
B 80
100
60 40 20 0
60
[Chlorophyll] (µg L-1)
[Chlorophyll] (µg L-1)
80
0
10
20
40
20
0
30
0
10
Time (min)
C
30
D
105
90
90
80 [Chlorophyll] (µg L-1)
[Chlorophyll] (µg L-1)
20 Time (min)
75 60 45 30 15
70 60 50 40 30 20 10
0
10
0
20
0
30
0
10
Time (min)
20
30
Time (min)
Fig. 2. Algae concentration along UV radiation experiments. Different initial algae concentration. (A) Chlorella, (B) Microcystis, (C) Oocystis, (D) Scenedesmus.
B 70
70
60
60
[Algae]0-[Algae] (µg L-1)
[Algae]0-[Algae] (µg L-1)
A
50 40 30 20 10 0 0E+0
1E-4
2E-4
3E-4
30 20 10 0 0E+0
2E-5
4E-5
6E-5
8E-5
D
80
50
70
45 [Algae]0-[Algae] (µg L-1)
[Algae]0-[Algae] (µg L-1)
40
4E-4
C
60 50 40 30 20 10 0 0E+0
50
40 35 30 25 20 15 10 5
2E-5
4E-5
6E-5
8E-5
1E-4
0 0.E+0
5.E-4
1.E-3
2.E-3
Fig. 3. Quantum yield determination. Theoretical model. (A) Chlorella, (B) Microcystis, (C) Oocystis, (D) Scenedesmus.
Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030
G Model JIEC 3236 No. of Pages 4
4
M.M. Barrado-Moreno et al. / Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
Table 2 Influence of initial algae concentration in quantum yield. [Algae]0 (mg L1) Chlorella 25.43 47.19 74.06 Oocystis 23,53 47,91 79,08 Microcystis 30.33 48.57 76.32 Scenedesmus 26.36 51.42 70.48
Acknowledgments
f (mg E1)
fglobal (mg E1)
5.95 104 5 102 8.15 104 7 102 8.15 104 7 102
7.75 104 9 102
2.59 105 5 102 2.94 105 5 102 3.22 105 6 102
2.98 105 7 102
3.30 105 5 102 3.52 105 6 102 3.71 105 5 102
3.65 105 7 102
1.46 104 4 102 1.75 104 5 102 1.82 104 5 102
1.74 104 6 102
one of the experiments, carried out at different initial concentration of microalgae are very similar to one another. For this reason are presented jointly three experiments (with different initial concentration) for each of microalgae and an global quantum yield is obtained for each of them. It can be observed that quantum yield is practically not affected by the initial algae concentration as previous investigations reported [26]. Conclusions UV photodegradation process can be used to inactive microalgae from freshwater. The study of the influence of initial algae concentration shows that this not considerably influences the general result of the process. Scenedesmus is less reactive than the other algae to UV radiation. These algae are without difficulty inactivated by photodegradation with high quantum yields. General photoreaction can be described by application the Line Source Spherical Emission model resulting global quantum yields of 7.75 104, 3.65 105, 2.98 105, 1.74 104 mg L1 E1 for Chlorella, Microcystis, Oocystis and Scenedesmus respectively. UV technology has a promising future for the degradation of algae and other contaminants.
This investigation has been supported by the Comisión Interministerial de Ciencia y Tecnología (CICYT) CTM 201341354-R Project and Fundación Fernando Valhondo Calaff. References [1] Toxic Cyanobacteria in Water: A Guide to Their Public Health Consequences, Monitoring and Management, in: I. Chorus, J. Bartram (Eds.), E & FN Spon, London, 1999. [2] A.A. Ansari, S.G. Sarvajeet, G.R. Lanza, W. Rast, Eutrophication: Causes, Consequences and Control, Springer, New York, 2011. [3] M. Ma, R. Liu, H. Liu, J. Qu, W. Jefferson, Sep. Purif. Technol. 86 (2012) 19. [4] D. Vandamme, I. Foubert, I. Fraeye, K. Muylaert, Bioresour. Technol. 124 (2012) 508. [5] M. Campinas, M.J. Rosa, Sep. Purif. Technol. 70 (3) (2010) 345. [6] M.M. Barrado-Moreno, J. Beltran-Heredia, J. Martín-Gallardo, Toxicon 110 (2016) 68. [7] L. Li, N. Gao, Y. Deng, J. Yao, K. Zhang, Water Res. 46 (4) (2012) 1233. [8] K.I. Harada, Chem. Pharm. Bull. 52 (8) (2004) 889. [9] I. Udom, B.H. Zaribaf, T. Halfhide, B. Gillie, O. Dalrymple, O. Zhang, S.J. Ergas, Bioresour. Technol. 139 (2013) 101. [10] M.M. Barrado-Moreno, J. Beltrán-Heredia, J. Martín-Gallardo, J. Appl. Phycol. 28 (2015) 1589. [11] T. Coward, J.G.M. Lee, G.S. Caldwell, Algal Res. 2 (2013) 135. [12] D.J. Lee, G.Y. Liao, Y.R. Chang, J.S. Chang, Bioresour. Technol. 108 (2012) 184. [13] D.J. Oemcke, J. van Leeuwen, Water Res. 39 (2005) 5119. [14] L. Wang, J. Qiao, Y. Hu, L. Wang, L. Zhang, Q. Zhou, N. Gao, J. Environ. Sci. 25 (3) (2013) 452. [15] C.G. Alfafara, K. Nakano, N. Nomura, T. Igarashi, M. Matsumura, J. Chem. Technol. Biotechnol. 77 (8) (2002) 871. [16] G. Zhang, B. Wang, P. Zhang, L. Wang, H. Wang, J. Environ. Sci. Health A 41 (7) (2006) 1379. [17] M.D.Z. Bin Alam, M. Otaki, H. Furumai, S. Ohgaki, Water Res. 35 (4) (2001) 1008. [18] R.P. Qiao, N. Li, X.H. Qi, Q.S. Wang, Y.Y. Zhuang, Toxicon 45 (6) (2005) 745. [19] H. Sakai, H. Katayama, K. Oguma, S. Ohgaki, Environ. Sci. Technol. 43 (2009) 896. [20] APHA, Standard Methods for the Examination of Water and Wastewater, American Public Health Association and American Water Works Association and Water Environment Association, 2005. [21] J. Sánchez-Martín, J. Beltrán-Heredia, J.R. Domínguez, Water Air Soil Pollut. 224 (2013) 1483. [22] R.J. Porra, Photosynth. Res. 73 (2002) 149. [23] H.A. Irazoqui, M.A. Isla, A.E. Cassano, Ind. Eng. Chem. Res. 39 (11) (2000) 4260. [24] D.H. Volman, J.R. Seed, J. Am. Chem. Soc. 86 (23) (1964) 5095. [25] F.J. Benítez, J.L. Acero, F.J. Real, G. Roldan, F. Casas, Chem. Eng. J. 168 (3) (2011) 1149. [26] F.J. Benítez, J. Beltrán-Heredia, J.A. Peres, J.R. Dominguez, J. Hazard. Mater. 73 (2) (2000) 161.
Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030
Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Journal of Industrial and Engineering Chemistry journal homepage: www.elsevier.com/locate/jiec
Short communication
Degradation of microalgae from freshwater by UV radiation M.M. Barrado-Morenoa,* , J. Beltrán-Herediaa,1, J. Martín-Gallardob a b
Department of Chemical Engineering and Physical Chemistry, University of Extremadura, Avda. De Elvas, s/n, 06071 Badajoz, Spain Department of Plant Biology, Ecology and Earth Science, University of Extremadura, Avda. De Elvas, s/n, 06071 Badajoz, Spain
A R T I C L E I N F O
Article history: Received 19 January 2016 Received in revised form 30 May 2016 Accepted 26 December 2016 Available online xxx Keywords: Algae Freshwater Photodegradation UV radiation
A B S T R A C T
Algae (Chlorella,Microcystis, Oocystis and Scenedesmus) degradation by ultraviolet radiation has been investigated. The radiation source was a low pressure mercury vapor lamp which emits monochromatic radiation at 254 nm. Experiments include initial algae concentration variation. After a period of exposure to UV radiation, algal mass concentration was reduced by more than 80%. The results were interpreted under Line Source Spherical Emission model, so quantum yield was the appropriate target variable for explaining the process. Global quantum yields are determined for Chlorella, Microcystis, Oocystis and Scenedesmus being 7.75 104, 3.65 105, 2.28 105, 1.74 104 mg E1, respectively. © 2016 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.
Introduction Eutrophication is the enhancement of the natural process of biological production in rivers, lakes and reservoirs, caused by increases in levels of nutrients, usually phosphorus and nitrogen compounds [1]. Eutrophication was recognized as a pollution problem in many western European and North American lakes and reservoirs in the middle of the twentieth century [2]. At the present, eutrophication causes a number of deleterious effects on drinking water treatment: reduction of coagulation efficiency resulting in a rising coagulant demand [3,4], increased membrane fouling [5], filter clogging, higher yield of sludge as a result of an increased coagulant dose [6] and disinfection by-product formation [7]. In addition, algae organic matters affect the color, taste and odor of drinking water and a number of cyanobacterial species also excrete toxic metabolites which can cause health problems [8]. For these reasons, it is necessary to eliminate algae from drinking waters; suitable techniques are coagulation [9,10], flotation [11], filtration [12], ozonation [13], chlorination [3], oxidation by potassium permanganate [14], electrochemical [15] and ultrasound [16] treatments. Previous studies have shown that ultraviolet radiation (UV), especially the shortwave ultraviolet (UV-C at 254 nm) is highly effective for the removal of algae [17,18]. UV radiation degrades to the
* Corresponding author. E-mail addresses: [email protected], [email protected] (M.M. Barrado-Moreno), [email protected] (J. Beltrán-Heredia), [email protected] (J. Martín-Gallardo). 1 Fax: +34 924289385.
target DNA much more efficiently than chemical agents in water. Moreover, this generates no chemical waste in its germicide effects and produces comparably lower disinfection by products. Studies have bring to light that ultraviolet radiation at 254 nm is an alternative to inhibit blooms of cyanobacterias and green algae in lakes and reservoirs [19]. For these reasons, in this paper is studied the degradation of Chlorella, Microcystis, Oocystis and Scenedesmus algae by UV radiation. Materials and methods Reagents The trials were carried out with water from a creek (AEMET) in Badajoz (Southwestern of Spain, Extremadura Community). The basic characteristics [20] of these waters are shown in Table 1. Algae cultures were incubated at 25 C under white light photoperiod of 12:12 in a culture medium supplied by Fluka (Algae culture broth). Chlorella, Microcystis, Oocystis and Scenedesmus inoculums were provided by the Department of Botany, University of Coimbra (Portugal). Photochemical trials The assays were carried out in an installation previously described [21]. Figure drawing thereof is shown in Fig. 1. Algae inactivation was carried out as follows: 500 mL of a solution of algal mass concentration for each test is prepared. The exact concentration of algae is determined by measuring the
http://dx.doi.org/10.1016/j.jiec.2016.12.030 1226-086X/© 2016 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.
Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030
G Model JIEC 3236 No. of Pages 4
2
M.M. Barrado-Moreno et al. / Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
Table 1 Raw water characterization data. Parameter
Units
AEMET
pH Conductivity Turbidity Total solids KMnO4 oxidability Hardness
–
8.18 0.3 351 2 10.75 0.3 2.65 0.2 6.96 0.3 212 3
mS cm1 NTU g L1 mg O2 L1 mg CaCO3 L1
fluorescence of chlorophyll in a fluorimeter (Aquafluor) previously calibrated [22]. This solution was introduced in the photochemical reactor. The UV lamp was turned on, and samples (5 mL) were collected at regular time. The experiment usually lasted for 30 min. Actinometric reactions permit to characterize of the lamp emissivity. Uranyl oxalate was extensively considered as a reference according to the general method [23]. Uranyl sulfate (UO2SO43.5H2O) was supplied from Panreac, while oxalic acid (C2H2O4) and potassium permanganate (KMnO4) were purchased by Sigma Aldrich. Results and discussion Algae degradation tests were performed to obtain information about their efficiency in process of UV radiation. At first, viability of this photodegradation process was confirmed by evaluating the apparent decay in algae content. Finally, kinetic model was utilized to model the process of algae degradation. Algae degradation Algae degradation was tackled through three trial series in which initial algae concentration was 25, 50 and 75 mg L1. As it can be appraised in Fig. 2 Scenedesmus is less responsive than the other algae to UV radiation because Chlorella, Microcystis and Oocystis concentration are negligible after being subjected to 30 min of light exposure. This may be due to the size and structure of microalgae; Scenedesmus is larger and more robust than the other algae.
This is to verify the feasibility of this procedure in degrading this type of microalgae although it does not provide valuable information in terms of reaction rate; therefore does not allow the comparison under different experimental conditions. Kinetic studies It is labeled to identify a target variable that represents the reaction rate and effectiveness of the degradation process in a numerical way. For this purpose, classical studies implement the Line Source Spherical Emission (LSSE) model [24] and they are still in force [25]. In short, the basis of LSSE model is shown in previous publications [21]. Following the model described is obtained the value of total radiation flow emitted by the lamp, WL, for the current system was 2.80 106 E s1. Molar extinction coefficients values were determined for each alga: Chlorella: 2.50 103; Microcystis: 3.77 104; Oocystis: 3.18 104; Scenedesmus: 4.52 103 (mg 1 cm1 L). According to the model algae degradation can be represented by Eq. (1). Z f t Wabs dt ð1Þ CB ¼ CB0 V 0 Where CB0 and CB are the concentration of chlorophyll at the start and at any one time. V is the total volume of the liquid phase (L) and Wabs is the flow of radiant energy absorbed by the reaction medium (Eins s1). Therefore it is possible to determine, for each operation time, the corresponding m, Wabs and integral term in Eq. (1). The linear adjustment of this expression will lead to a constant slope that is representative of f. This f (chlorophyll degraded by photons absorbed) is the kinetic parameter (called quantum yield) which allows us to compare different efficiencies at various operating conditions, hence, it can determine how the system responds to operational changes and, finally, to propose a theoretical or empirical model. In Fig. 3 it can be observed the graphical representations of these linear adjustments. Values quantum yields obtained are shown in Table 2. It can be seen that the quantum yields for each
Fig. 1. UV installation.
Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030
G Model JIEC 3236 No. of Pages 4
M.M. Barrado-Moreno et al. / Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
A
3
B 80
100
60 40 20 0
60
[Chlorophyll] (µg L-1)
[Chlorophyll] (µg L-1)
80
0
10
20
40
20
0
30
0
10
Time (min)
C
30
D
105
90
90
80 [Chlorophyll] (µg L-1)
[Chlorophyll] (µg L-1)
20 Time (min)
75 60 45 30 15
70 60 50 40 30 20 10
0
10
0
20
0
30
0
10
Time (min)
20
30
Time (min)
Fig. 2. Algae concentration along UV radiation experiments. Different initial algae concentration. (A) Chlorella, (B) Microcystis, (C) Oocystis, (D) Scenedesmus.
B 70
70
60
60
[Algae]0-[Algae] (µg L-1)
[Algae]0-[Algae] (µg L-1)
A
50 40 30 20 10 0 0E+0
1E-4
2E-4
3E-4
30 20 10 0 0E+0
2E-5
4E-5
6E-5
8E-5
D
80
50
70
45 [Algae]0-[Algae] (µg L-1)
[Algae]0-[Algae] (µg L-1)
40
4E-4
C
60 50 40 30 20 10 0 0E+0
50
40 35 30 25 20 15 10 5
2E-5
4E-5
6E-5
8E-5
1E-4
0 0.E+0
5.E-4
1.E-3
2.E-3
Fig. 3. Quantum yield determination. Theoretical model. (A) Chlorella, (B) Microcystis, (C) Oocystis, (D) Scenedesmus.
Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030
G Model JIEC 3236 No. of Pages 4
4
M.M. Barrado-Moreno et al. / Journal of Industrial and Engineering Chemistry xxx (2016) xxx–xxx
Table 2 Influence of initial algae concentration in quantum yield. [Algae]0 (mg L1) Chlorella 25.43 47.19 74.06 Oocystis 23,53 47,91 79,08 Microcystis 30.33 48.57 76.32 Scenedesmus 26.36 51.42 70.48
Acknowledgments
f (mg E1)
fglobal (mg E1)
5.95 104 5 102 8.15 104 7 102 8.15 104 7 102
7.75 104 9 102
2.59 105 5 102 2.94 105 5 102 3.22 105 6 102
2.98 105 7 102
3.30 105 5 102 3.52 105 6 102 3.71 105 5 102
3.65 105 7 102
1.46 104 4 102 1.75 104 5 102 1.82 104 5 102
1.74 104 6 102
one of the experiments, carried out at different initial concentration of microalgae are very similar to one another. For this reason are presented jointly three experiments (with different initial concentration) for each of microalgae and an global quantum yield is obtained for each of them. It can be observed that quantum yield is practically not affected by the initial algae concentration as previous investigations reported [26]. Conclusions UV photodegradation process can be used to inactive microalgae from freshwater. The study of the influence of initial algae concentration shows that this not considerably influences the general result of the process. Scenedesmus is less reactive than the other algae to UV radiation. These algae are without difficulty inactivated by photodegradation with high quantum yields. General photoreaction can be described by application the Line Source Spherical Emission model resulting global quantum yields of 7.75 104, 3.65 105, 2.98 105, 1.74 104 mg L1 E1 for Chlorella, Microcystis, Oocystis and Scenedesmus respectively. UV technology has a promising future for the degradation of algae and other contaminants.
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Please cite this article in press as: M.M. Barrado-Moreno, et al., Degradation of microalgae from freshwater by UV radiation, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2016.12.030