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Removal of refractory organics and color in pigment wastewater with Fenton oxidation
~
Wal. ScI Tech Vol. 39, No. 10-11, pp. 189-192,1999 e 1999 Published by Elsevier Science Ud on behalf of the IAWQ Printed in Great Britain. All nghts reserved 0273-1223/99 S20.00 + 0.00
Pergamon
po: S0273-1223(99)00274-7
REMOVAL OF REFRACTORY ORGANICS AND COLOR IN PIGMENT WASTEWATER WITH FENTON OXIDATION T. J. Park, K. H. Lee, E. J. Jung and C. W. Kim DepartmentofEnvironmentalEngineering, Pusan National University, Pusan. Korea, 609-735
ABSTRACT This study was designed to evaluate (I) the removal of the non-biodegradable organics and color by Fenton's oxidation (2) the feasibility of Fenton's oxidation as a pretreatment or tertiary treatment following the activated sludge process in the pigment wastewater. The study was divided into two parts . The first part consisted of investigations on raw Yellow wastewater and Red wastewater, the second part was carried out on the fJ.Da1 effluent from the existing extended aeration treatment plan t. The batch test was conducted to determine the optimum cond itions for plant operation such as pH. HzO z dosage , molar ratio of FeZ,IHzO z and contact time. It was found that the removal efficiencies of COD were 54.2%, 52.6% and 58.9%, the removal efficiencies of the color were 9\.2%, 18.1% and 45 .7%, for Red, Yellow Wastewater and Final Effluent, respectively. In the Yellow wastewater, BODs/COD ratio was not changed much after Fenton's oxidation, but in the case of the Red wastewater. BOD,ICOD ratio was increased from 0.04 to 0.36 . Therefore Fenton's oxidation process is a very effective means for a pretreatment or tertiary treatment in the Pigment wastewater. to 1999 Published by Elsev ier Science Ltd on behalf of the IAWQ. All rights reserved
KEYWORDS Fenton's oxidation; pretreatment; tertiary treatment; pigment wastewater; COD; color; BODs/COD. INTRODUCTION Pigment wastewaters are characterized by high levels of COD, BODs, color, concentration of suspended solids and so on (Kuo, 1992; Lin, 1993; Solozhenko, 1995). Especially, because the pigment molecules are highly structured polymers and are toxic to microorganism, biological treatment of these wastewaters will not remove all organics and the effluents of the biological purification stages exhibit COD values which may exceed discharge standards or which are serious from an ecological point of view (Halliday, 1986; Lin, 1993). Therefore, a new method of treating pigment wastewater like Fenton's oxidation is required to: (i) reduce organic content; COD, BODs and color and (ii) minimize the hazard caused by the pigments. Fenton's reagent is defined as the catalytic generation of hydroxyl radicals from the chain reaction between ferrous iron and hydrogen peroxide and has been shown to effectively oxidize a variety of toxic and refractory organic compounds (Flaherty, 1992).
The main reactions are: Fe2+ + H20 2 Fe3+ + H20 2
Fe2+ + OIr + HO· Fe2+ + H+ + HOr
(1)
(2) 189
190
T.J.PARKetal.
It is known that [Fe2+], [H202] and [OHO] directly influence the concentration of hydroxyl free radical generated and determine the rate of oxidation reaction from equation (1). In this study, we have determined the optimum conditions for plant operation such as pH, H20 2 dosage, molar ratio of Fe2+1H202 and reaction time by batch tests.
MATERIALS AND METHODS Experimental procedures There are several steps to conduct Fenton' reagent reactions. Take 500ml-wastewater sample in a II beaker on the jar tester. Adjust its pH with dilute sulfuric acid or sodium hydroxide to the required value. Add the proper volume of 30% H202 and 30% FeS04' 7H20 and tum on a jar tester. After the definite reaction time, adjust its pH to 8.0-8.5 and let it stand for Ihr, Take the upper liquid and measure its COD, BODs, absorbance in the visible light spectrum (color) and residual H20 2 values. Analytical methods COD and BODs analyses of each sample was performed according to Standard Methods (17th edition). The pH value of each sample is measured by a digital pH meter (Model HM-14P, TOA, Japan). Color changes were quantified utilizing a Shimadzu 260 UV-visible recording spectrophotometer. RESULTS AND DISCUSSION The pigment wastewater was characterized according to pH, COD, BODs and Absorbance. The characteristics of all wastewaters tested are given in Table 1. Table 1. Characteristics ofpigment wastewaters used in this work
pH COD BODs Abs. 266nm 337nm 454nm
Red Wastewater 9.67 2,728 309
Yellow Wastewater 4.24 28,621 21,081
Final Effiuent 7.75 336 62
2.274 1.230 1.479
1.623 0.840 0.550
3.436 0.471 0.070
Treatment of raw Red wastewater The batch test was conducted to determine the optimum conditions for plant operation such as pH, H202 dosage, molar ratio of Fe2+1H202 and contact time. Figures 1 and 2 show the effect of oxidation time on the removal of COD and color for the Fenton's oxidation with a pH, Fe2+1H202 ratio and hydrogen peroxide dose of 5.0, 0.1 and 5g11, respectively. Azo dyes are characterized by nitrogen to nitrogen double bonds (N=N). The color of azo dyes is due to azo bonds and associated chromophores (Gregory, 1994). In the absorption spectra of the reagent mixture, one can observe a decrease in the intensity of bands with the maximum at 454nm (n ~ 7t* transition in N=N group), 266nm (7t~ 7t* transitions in benzene rings) and 337nm(interaction of aromatic 7t-systems through an interspace). This is due to oxidation of the above fragments during the reaction and to the loss of conjugation in dye molecules, resulting in the decolourization of azodye solutions (Solozhenko, 1995). The results indicate that for an oxidation time of 0.5hr, 54.2% of COD and 91.2% of color (454nm) were removed.
191
Rem oval of refra ctory organics and color
40 00
...
3000
~
E
e
.6
2000
.4
~e
100 0
.2
ci'
Co
e
2.S ...-- - - - --
.8 p H : S.O H,O, : ~OOOml 'L Fe h /H,O, : 0. 1
Te mperatu re: 20 .8 °c
e
0
(,)
CD
u
-
--,
F e z' / H IO I : 0.1
c
~
I.S
~
1.0
c{
Tempera ture : 20.8
°c
<;
0
.5
o 0
-
pH : 5.0 " to) : 500 0 mg / L
2 .0
0 .0 0
3
Rea c tion time, hr
Rea c tio n time , hr
I. Figure 1. COD removal V5. reaction time for Red wast ewater
4 S4nm
•
lJ lnm
....
266nm
I
Figure 2. Color removal vs. rea ction time for Red wastewater.
Treatment of raw Yellow wastewater Figures 3 and 4 show the color Absorbance and COD reduction during the reaction time of Fenton's oxidation in a batch reactor. The Fenton's oxidation with a pH, Fe2+/th 02 ratio and hydrogen peroxide dose of 4.0, 0.08 and 80,000mg/l, respectively, indicate the optimum reaction time was Ihr and the removal efficiencies of COD and color (454nm) were 52.57% and 18.1% respectively.
...
SO
.4
;;,
.'"e e
.
40
0 (,)
e
H 10 1
0
:
'"
80 00 0m c / L
FeZ"IH, O , : 0.08 Temperaturt : I8 .J -C
.3
'" :!;
.2
U c
e
30
u
C
20
~
\:
0
2 .0 ...-- - - - -- - - - - - - - - ,
.~ ~.
~
pH : " .0 H 10 1
1.0
.5
\
--
~6--_--"'"
3
Re ac ti o n time, hr
10
CODe,
•
CODer nm ·1lt 101
8000 0m l JL
\
.1
0
:
Fe z<'H 10 J : 0 .08 T'emp e r atu r e : IS .J o e
1.5 [\
(J
~
10
E
p H : .. .0
---
~
Re a c tl o n ti m e, hr
um·1
Figure 3. COD removal vs . reaction time for Yellow wastewater.
I_
4 S4 n m
•
.l3 7nm
'"
26 6nm
I
Figure 4. Color removal vs . reaction time for Yellow was tewater.
In Red wastewater, the visible color turned from dark red to light yellow and BODs/COD ratio was increased 0.04 to 0.36 but in Yellow wastewater, the appreciable change of the color and BODs/COD was not observed. Treatment of Final effluent In !~e experiment of the Final effluent, the optimum conditions of Fenton's oxidation were 3.0 of pH, DAD of Fe IH202 and Ihr of reaction time. In this time, The removal efficiencies of COD, color (454nm) were 58.9%, 45.7%, respectively. In addition, The final water quality value of COD can meet the more stringent effluent standards . The optimum conditions tested and the removal efficiencies of COD and color are given in Table 2.
T. J. PARKetal.
192
Table 2. Fenton's oxidation results Wastewater
pH
Fel+1H 202 (molar ratio)
Red
5.0
0.10
Yellow
4.0
0.08
1.0
52.57
18.1
Final
3.0
0.40
0.5
58.90
45.7
Reaction time COD Color (hr) Removal (%) Removal (%) 0.5 54.20 91.2
CONCLUSIONS The treatment of the Red wastewater was more effective at reducing loadings of COD and color as well as enhancing the biodegradability of raw wastewater than the Yellow wastewater using Fenton's oxidation. The treatment of the Final effiuent using Fenton's oxidation resulted in significant removal efficiency for COD and color. Hence, Fenton's oxidation process can be a very effective means for a pretreatment or tertiary treatment in the Pigment wastewater. ACKNOWLEDGMENTS The authors wish to acknowledge the financial support provided by the Ministry of the Environment, Korea and Songwon Color Co, Korea, as a part of a G-7 project, "Development of Control and Automation Technologies for Wastewater Treatment Plants". REFERENCES Flaherty, K. A. and Huang, C. P. (1992). Continuous flow applications of fenton's reagent for the treatment of refractory wastewaters. Proceedings ofthe Second International Symposium, Tennessee, USA, 58-73. Ganesh, R., Boardman, G. D. and Michelsen, D. (1994). Fate ofazo dye in sludges. Wat. Res., 28(4),1367-1376. Halliday, P. J. and Beszedits, S. (1986). Color removal from textile null wastewaters. Canadian Textilelournal. April, 78-84. Kuo, W. G. (1992). Decolorizing dye wastewater with Fenton's reagent. Wat. Res., 26(7), 881-886. Kang Shyh-Fang, Hsu Shen-Che and Chang Huey-Min (1997). Coagulation of textile secondaryeffiuents with Fenton's reagent. 6th IAWQ Asia-Pacific Regional Conference, Seoul, Korea, Vol(lI)., 1249-1256. Lin Sheng, H. and Lin Chi, M. (1993). Treatment of' textile waste effiuents by ozonation and chemicalcoagulation. Wat. Res., 27(12), 1743-1748. Sedlak, D. L. and Andren, A. W. (1991). Oxidation of chlorobenzene with Fenton's Reagent. Environ. Sci Technol., 25(4), 777-782. Solozhenko, E. G., Soboleva, N. M. and Goncharuk, V. V. (1995). Decolorization ofazodye solutions byfenton's oxidation. Wat. Res., 29(9), 2206-2210. Wanpeng Zhu, Zhihua Yang and LI Wang (1996). Application of ferrous-hydrogen peroxide for the treatment of h-acid manufactunng process wastewater. Wat. Res., 30(12), 2949-2954.
Wal. ScI Tech Vol. 39, No. 10-11, pp. 189-192,1999 e 1999 Published by Elsevier Science Ud on behalf of the IAWQ Printed in Great Britain. All nghts reserved 0273-1223/99 S20.00 + 0.00
Pergamon
po: S0273-1223(99)00274-7
REMOVAL OF REFRACTORY ORGANICS AND COLOR IN PIGMENT WASTEWATER WITH FENTON OXIDATION T. J. Park, K. H. Lee, E. J. Jung and C. W. Kim DepartmentofEnvironmentalEngineering, Pusan National University, Pusan. Korea, 609-735
ABSTRACT This study was designed to evaluate (I) the removal of the non-biodegradable organics and color by Fenton's oxidation (2) the feasibility of Fenton's oxidation as a pretreatment or tertiary treatment following the activated sludge process in the pigment wastewater. The study was divided into two parts . The first part consisted of investigations on raw Yellow wastewater and Red wastewater, the second part was carried out on the fJ.Da1 effluent from the existing extended aeration treatment plan t. The batch test was conducted to determine the optimum cond itions for plant operation such as pH. HzO z dosage , molar ratio of FeZ,IHzO z and contact time. It was found that the removal efficiencies of COD were 54.2%, 52.6% and 58.9%, the removal efficiencies of the color were 9\.2%, 18.1% and 45 .7%, for Red, Yellow Wastewater and Final Effluent, respectively. In the Yellow wastewater, BODs/COD ratio was not changed much after Fenton's oxidation, but in the case of the Red wastewater. BOD,ICOD ratio was increased from 0.04 to 0.36 . Therefore Fenton's oxidation process is a very effective means for a pretreatment or tertiary treatment in the Pigment wastewater. to 1999 Published by Elsev ier Science Ltd on behalf of the IAWQ. All rights reserved
KEYWORDS Fenton's oxidation; pretreatment; tertiary treatment; pigment wastewater; COD; color; BODs/COD. INTRODUCTION Pigment wastewaters are characterized by high levels of COD, BODs, color, concentration of suspended solids and so on (Kuo, 1992; Lin, 1993; Solozhenko, 1995). Especially, because the pigment molecules are highly structured polymers and are toxic to microorganism, biological treatment of these wastewaters will not remove all organics and the effluents of the biological purification stages exhibit COD values which may exceed discharge standards or which are serious from an ecological point of view (Halliday, 1986; Lin, 1993). Therefore, a new method of treating pigment wastewater like Fenton's oxidation is required to: (i) reduce organic content; COD, BODs and color and (ii) minimize the hazard caused by the pigments. Fenton's reagent is defined as the catalytic generation of hydroxyl radicals from the chain reaction between ferrous iron and hydrogen peroxide and has been shown to effectively oxidize a variety of toxic and refractory organic compounds (Flaherty, 1992).
The main reactions are: Fe2+ + H20 2 Fe3+ + H20 2
Fe2+ + OIr + HO· Fe2+ + H+ + HOr
(1)
(2) 189
190
T.J.PARKetal.
It is known that [Fe2+], [H202] and [OHO] directly influence the concentration of hydroxyl free radical generated and determine the rate of oxidation reaction from equation (1). In this study, we have determined the optimum conditions for plant operation such as pH, H20 2 dosage, molar ratio of Fe2+1H202 and reaction time by batch tests.
MATERIALS AND METHODS Experimental procedures There are several steps to conduct Fenton' reagent reactions. Take 500ml-wastewater sample in a II beaker on the jar tester. Adjust its pH with dilute sulfuric acid or sodium hydroxide to the required value. Add the proper volume of 30% H202 and 30% FeS04' 7H20 and tum on a jar tester. After the definite reaction time, adjust its pH to 8.0-8.5 and let it stand for Ihr, Take the upper liquid and measure its COD, BODs, absorbance in the visible light spectrum (color) and residual H20 2 values. Analytical methods COD and BODs analyses of each sample was performed according to Standard Methods (17th edition). The pH value of each sample is measured by a digital pH meter (Model HM-14P, TOA, Japan). Color changes were quantified utilizing a Shimadzu 260 UV-visible recording spectrophotometer. RESULTS AND DISCUSSION The pigment wastewater was characterized according to pH, COD, BODs and Absorbance. The characteristics of all wastewaters tested are given in Table 1. Table 1. Characteristics ofpigment wastewaters used in this work
pH COD BODs Abs. 266nm 337nm 454nm
Red Wastewater 9.67 2,728 309
Yellow Wastewater 4.24 28,621 21,081
Final Effiuent 7.75 336 62
2.274 1.230 1.479
1.623 0.840 0.550
3.436 0.471 0.070
Treatment of raw Red wastewater The batch test was conducted to determine the optimum conditions for plant operation such as pH, H202 dosage, molar ratio of Fe2+1H202 and contact time. Figures 1 and 2 show the effect of oxidation time on the removal of COD and color for the Fenton's oxidation with a pH, Fe2+1H202 ratio and hydrogen peroxide dose of 5.0, 0.1 and 5g11, respectively. Azo dyes are characterized by nitrogen to nitrogen double bonds (N=N). The color of azo dyes is due to azo bonds and associated chromophores (Gregory, 1994). In the absorption spectra of the reagent mixture, one can observe a decrease in the intensity of bands with the maximum at 454nm (n ~ 7t* transition in N=N group), 266nm (7t~ 7t* transitions in benzene rings) and 337nm(interaction of aromatic 7t-systems through an interspace). This is due to oxidation of the above fragments during the reaction and to the loss of conjugation in dye molecules, resulting in the decolourization of azodye solutions (Solozhenko, 1995). The results indicate that for an oxidation time of 0.5hr, 54.2% of COD and 91.2% of color (454nm) were removed.
191
Rem oval of refra ctory organics and color
40 00
...
3000
~
E
e
.6
2000
.4
~e
100 0
.2
ci'
Co
e
2.S ...-- - - - --
.8 p H : S.O H,O, : ~OOOml 'L Fe h /H,O, : 0. 1
Te mperatu re: 20 .8 °c
e
0
(,)
CD
u
-
--,
F e z' / H IO I : 0.1
c
~
I.S
~
1.0
c{
Tempera ture : 20.8
°c
<;
0
.5
o 0
-
pH : 5.0 " to) : 500 0 mg / L
2 .0
0 .0 0
3
Rea c tion time, hr
Rea c tio n time , hr
I. Figure 1. COD removal V5. reaction time for Red wast ewater
4 S4nm
•
lJ lnm
....
266nm
I
Figure 2. Color removal vs. rea ction time for Red wastewater.
Treatment of raw Yellow wastewater Figures 3 and 4 show the color Absorbance and COD reduction during the reaction time of Fenton's oxidation in a batch reactor. The Fenton's oxidation with a pH, Fe2+/th 02 ratio and hydrogen peroxide dose of 4.0, 0.08 and 80,000mg/l, respectively, indicate the optimum reaction time was Ihr and the removal efficiencies of COD and color (454nm) were 52.57% and 18.1% respectively.
...
SO
.4
;;,
.'"e e
.
40
0 (,)
e
H 10 1
0
:
'"
80 00 0m c / L
FeZ"IH, O , : 0.08 Temperaturt : I8 .J -C
.3
'" :!;
.2
U c
e
30
u
C
20
~
\:
0
2 .0 ...-- - - - -- - - - - - - - - ,
.~ ~.
~
pH : " .0 H 10 1
1.0
.5
\
--
~6--_--"'"
3
Re ac ti o n time, hr
10
CODe,
•
CODer nm ·1lt 101
8000 0m l JL
\
.1
0
:
Fe z<'H 10 J : 0 .08 T'emp e r atu r e : IS .J o e
1.5 [\
(J
~
10
E
p H : .. .0
---
~
Re a c tl o n ti m e, hr
um·1
Figure 3. COD removal vs . reaction time for Yellow wastewater.
I_
4 S4 n m
•
.l3 7nm
'"
26 6nm
I
Figure 4. Color removal vs . reaction time for Yellow was tewater.
In Red wastewater, the visible color turned from dark red to light yellow and BODs/COD ratio was increased 0.04 to 0.36 but in Yellow wastewater, the appreciable change of the color and BODs/COD was not observed. Treatment of Final effluent In !~e experiment of the Final effluent, the optimum conditions of Fenton's oxidation were 3.0 of pH, DAD of Fe IH202 and Ihr of reaction time. In this time, The removal efficiencies of COD, color (454nm) were 58.9%, 45.7%, respectively. In addition, The final water quality value of COD can meet the more stringent effluent standards . The optimum conditions tested and the removal efficiencies of COD and color are given in Table 2.
T. J. PARKetal.
192
Table 2. Fenton's oxidation results Wastewater
pH
Fel+1H 202 (molar ratio)
Red
5.0
0.10
Yellow
4.0
0.08
1.0
52.57
18.1
Final
3.0
0.40
0.5
58.90
45.7
Reaction time COD Color (hr) Removal (%) Removal (%) 0.5 54.20 91.2
CONCLUSIONS The treatment of the Red wastewater was more effective at reducing loadings of COD and color as well as enhancing the biodegradability of raw wastewater than the Yellow wastewater using Fenton's oxidation. The treatment of the Final effiuent using Fenton's oxidation resulted in significant removal efficiency for COD and color. Hence, Fenton's oxidation process can be a very effective means for a pretreatment or tertiary treatment in the Pigment wastewater. ACKNOWLEDGMENTS The authors wish to acknowledge the financial support provided by the Ministry of the Environment, Korea and Songwon Color Co, Korea, as a part of a G-7 project, "Development of Control and Automation Technologies for Wastewater Treatment Plants". REFERENCES Flaherty, K. A. and Huang, C. P. (1992). Continuous flow applications of fenton's reagent for the treatment of refractory wastewaters. Proceedings ofthe Second International Symposium, Tennessee, USA, 58-73. Ganesh, R., Boardman, G. D. and Michelsen, D. (1994). Fate ofazo dye in sludges. Wat. Res., 28(4),1367-1376. Halliday, P. J. and Beszedits, S. (1986). Color removal from textile null wastewaters. Canadian Textilelournal. April, 78-84. Kuo, W. G. (1992). Decolorizing dye wastewater with Fenton's reagent. Wat. Res., 26(7), 881-886. Kang Shyh-Fang, Hsu Shen-Che and Chang Huey-Min (1997). Coagulation of textile secondaryeffiuents with Fenton's reagent. 6th IAWQ Asia-Pacific Regional Conference, Seoul, Korea, Vol(lI)., 1249-1256. Lin Sheng, H. and Lin Chi, M. (1993). Treatment of' textile waste effiuents by ozonation and chemicalcoagulation. Wat. Res., 27(12), 1743-1748. Sedlak, D. L. and Andren, A. W. (1991). Oxidation of chlorobenzene with Fenton's Reagent. Environ. Sci Technol., 25(4), 777-782. Solozhenko, E. G., Soboleva, N. M. and Goncharuk, V. V. (1995). Decolorization ofazodye solutions byfenton's oxidation. Wat. Res., 29(9), 2206-2210. Wanpeng Zhu, Zhihua Yang and LI Wang (1996). Application of ferrous-hydrogen peroxide for the treatment of h-acid manufactunng process wastewater. Wat. Res., 30(12), 2949-2954.