International Journal of Scientific & Engineering Research, Volume 4, Issue Ş, 2013
ISSN 2229-5518
Comparison between the biodecolorization of
Reactive Dye by Single & Mix-Bacterial Strains
Jannatul Ferdous Rumky, Hafizur Rahman, M.Ali Hossain
Abstract— In the present study, an attempt was made to examine the potential of different bacterial strains (E.coli, Enterobacter & mix- bacterial strain) for decolorization of Sunfix Red (reactive dye), in static system . The effect of initial dye concentration, pH and static- rotating conditions were studied to measure the optimal conditions of degradation. Here, the bacterial mediums used in this study were E.coli, Enterobacter and mix-bacterial of them. Out of these, maxmimum decolorization emergerd out to be the most potent decolorizer among all. These bacterial strains showed higher decolorization in static medium in comparison with rotating condition. The optimum pH for decolorization of sunfix red by E.coli, Enterobacter & mix-bacterial strains were 8, 9, and 9. The optimum dye concentrations for these ones were 700,500 & 700 ppm. The optimum temperature was 37°C and the strain would decolorize 90-97% within 48 hours under the optimum conditions and the initial dye concentration was 300 ppm. The results showed that, the mix-bacterial strain has more good potential than single bacterial strain in removal of reactives dye from wastewater.
Index Terms— Bacterial strain, concentration, decolorization, E.coli, Enterobacter, pH, static, sunfix red.
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extile is the most significant sector of Bangladesh’s econ- omy. Textile industry uses large amount of water in its manufacture processes and highly polluted and toxic waste waters are discharged into sewers and drains without any kind of treatment. The textile dyeing industries of Bangla- desh generate large amount of effluents, sewage sludge and solid waste materials everyday which are being directly dis- charged into the neighboring channel, rural fields, irrigation channels, surface water and these finally enter in to rivers. Textile and dyeing industrial effluents may cause variation of the physical, chemical, and biological properties of aquatic environment by continuous change in temperature, odor, noise, turbidity etc that is harmful to public health, livestock, wildlife, fish, and other biodiversity. The presence of dyes in surface and subsurface water is making them not only aesthet- ically ojectionable but also causes many water borne diseases.
[1]
Although several physical-chemical methods have been
used to eliminate the colored effluents in wastewater, they are
generally expensive, produce large amounts of sludge. More
often these conventional modes of treatment lead to the forma-
tion of some harmful side products. Interest is therefore now
focused on the microbial biodegradation of dyes as a better alternative. Some microorganisms, including bacteria, fungi
and algae, can degrade or absorb a wide range of dyes .The biological mode of treatment of dye bath effluents offers dis- tinct advantages over the conventional modes of treatment. [2] This method is more economical and leads to less accumu- lation of relatively harmless sludge. Most importantly, biolog-
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Jannatul Ferdous Rumky, M.Sc Student, Dept. of Environmental Science, Independent University, Bangladesh. PH-+8801744302597.
E-mail: rumkyjannat@gmail.com
Hafizur Rahaman, Assistant Professor, Independent University, Bangladesh.
PH-+8801916108925. E-mail: pallab129@yahoo.com
M.Ali Hossain, Professor, Independent University, Bangladesh.
PH-+8801714326347. E-mail: mahossain@iub.edu.bd
ical treatment of dye bath effluents is ecofriendly. It causes mineralion of dyes to simpler inorganic compounds which are not lethal to life forms. In view of these problems the most potent bacterial culture was selected in this study for maxi- mum decolorization of Sunfix Red (reactive dye) [3], being selected as model azo dye.
Sunfix red supplied by MERK (Germany) was used & 1000 ppm stock solution was prepared by dissolving 1000 mg of it in 1000 ml of distilled water and the required solutions were prepared by suitably dilution of it.
Bacterial culture medium was made by adding specific amount of nutrient agar into distilled water. Next the solution was autoclaved at 121ºC for 30 minutes and cooled down up to 60°C. The solution was put on a petridish for solidification. Finally bacterial culture medium was inoculated & kept them in incubator at 37°C for bacterial growth. The culture medium was preserved in refrigerator for further use.
5ml bacterial suspension of each inoculum was inoculated in
250 mL nutrient broth flasks containing 300 mg/L dye solu-
tion incubated at 37C to study the growth curve of E.coli,
Enterobacter & mix-bacterial strains. Growth curve studied in nutrient broth with or without dyes to compare the death
phase of culture medium. Lack of glucose inhibited the deco- lorizing activity of single & mix bacterial (E.coli & Enterobac-
ter) strain.
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ISSN 2229-5518
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The bacterial cultures were transferred to fresh nutrient me- dium containing sunfix red (300 mg/l) and were incubated at
37°C, under static condition for 3 days. Between this 3 day period, aliquots (5ml) of the culture media were withdrawn, centrifuged at 10,000 rpm for 10 minutes at room temperature to separate the bacterial cell mass. The supernatant was used for analysis of decolonization and all the experiments were repeated.
The Absorbance vs. Concentration of Sunfix Red dye solution is presented in figure - 2
From the above plot, it is seen that the absorbance vs. con- centration curve is a straight line passing through the origin. The correlation coefficient (R2) of the line is 0.999. The equa- tion of the line is the calibration equation and is used to de- termine the unknown concentrations of the solutions from absorbance.
From the plot, the calibration equation is
0.10
0.08
0.06
0.04
R2=0.999 y=0.003x
Fig 1: Sunfix Red decolorization by bacterial strains
0.02
0.00
0 5 10 15 20 25
Concentration
In an attempt to study the effect of static and shaking (100 rpm) condition, the selected, most potent decolorizing bacteri- al culture, was cultivated for 72 hrs in nutrient broth and amended separately with 300 mg/l of sunfix red. This inspec- tion was performed for the detection of decolorizing activity of bacteria & find out that static medium was more useful than rotating condition. So, static condition was selected for further experiments.
To determine the effect of pH on decolorization, the fully- grown culture was inoculated in conical flasks containing 100 ml nutrient broth of varying pH (6-9) and was amended with
300 mg/l of sunfix red. The pH values were adjusted using 1N
NaOH and 1M HCl. The result of this study can be concluded
that mix-bacteria (E.coli & Enterobacter) could be used effec-
tively for the removal of sunfix red from aqueous solution.
The adsorption capacity was found to be high at higher pH
range. For concentration difference study, media was amended with the dye sunfix red at a concentration of 100,
300, 500, 700 and 900 mg/l separately to study the effect of increasing dye concentration on percentage dye decolorization
& finally calculated the results.
The dye concentrations were measured with a UV/VIS
spectrophotometer [4] at regular intervals during the decolori- zation process. The concentration of reactive dye was detected
spectrophotometrically by reading the culture supernatant after a certain period of time and calculates the % of decolori- zation by using below equation 1.
Fig 2: Calibration Curve of Sunfix Red
From the above graphs, for E.coli bacteria, the death phase started after 65 hrs in presence of dye in comparison with non- dye solution started death phase after 47 hrs. For Enterobacter bacteria, the death phase started after 63 hrs in presence of dye in comparison with 55 hrs of nutrient broth without dye solu- tion. For mix-bacterial strains, the death phase started after 64 hrs in presence of dye in comparison with 50 hrs of nutrient broth without dye solution.
Growth Curve of E.coli Growth Curve of Enterobacter Growth Curve of mix-bacterial strain
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0 20 40 60 80 100
Time (hr)
Fig 3: Growth Curve Study (Bacterial culture with dye solution, dye conc. 300 ppm, aliquots of bacterial culture 5ml, time 100 hrs)
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Growth Curve of E.coli
Growth Curve of Enterobacter
3.5 Growth Curve of mix-bacterial strain
3.0
100
Decolorization by E.coli Decolorization by Enterobacter Decolorization by Mix-bacterial strains
2.5 80
2.0
1.5 60
1.0
40
0.5
0.0 20
0 10 20 30 40 50 60 70
Time (hr)
Fig 4: Growth Curve Study (Bacterial culture without dye solution, dye conc. 300 ppm, aliquots of bacterial culture 5ml, time 70 hrs)
0
6.0 6.5 7.0 7.5 8.0 8.5 9.0
Two opinions have been argued for many years: one deems that dyes are not a carbon source since the anaerobic bacteria obtain energy from the glucose instead of the dyes and glu-
Fig 5: Decolorization at different pH (dye conc. 300 ppm, aliquots of bacterial culture 5ml/100ml, time 72 hrs)
Decolorization by E.coli
cose can enhance the decolorizing performance of biological
systems. [5] While another deems that glucose can inhibit the decolorizing activity. The variability may be due to the differ-
ent microbial characteristics involved. Our results showed that a certain concentration of carbon source was necessary for all bacterial culture medium.
The best results were achieved at pH 8.0, 9.0, 9.0 for sunfix red by E.coli, Enterobacter & mix-bacterial strain bacteria with
90%, 94% & 97 % decolorization in 72 h. This could be due to the fact that the optimum pH for the growth of E.coli was neu- tral or slightly alkaline. The rate of color removal was much lower at strongly acidic medium. pH has a major effect on the efficiency of dye decolorization, and the optimal pH for color removal is often between 6.0 and 10.0. The pH tolerance of
100
80
60
40
20
Decolorization by Enterobacter
Decolorization by Mix-bacterial strains
200 400 600 800
Concentration
decolorizing bacteria is quite important because of binding to different fibers by addition or substitution mechanisms de- pend on acid-alkaline conditions. The fact that E.coli, Entero- bacter, mix-bacterial strains might decolorize reactive dyes in a relatively wide range of pH, make them suitable for practical bio-treatment of dyeing mill effluents.
For concentration difference study, media was amended with the dye sunfix red at a concentration of 100, 300, 500, 700 and 900 mg/l separately to study the effect of increasing dye concentration on percentage dye decolorization & finally cal- culated the results. Here, 700mg/l, 500 mg/l & 700mg/l showed the best end results for E.coli, Enterobacter & mix- bacterial strain.
Fig 6: Decolorization at different conc. (pH 7.0, aliquots of
bacterial culture 5ml/100ml, time 72 hrs)
TABLE 1
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TABLE 2
Initial Conc. of dye | Decolorization by E.coli | Decolorization by Enterobacter | Decolorization by Mix-actreial strain (E.coli & Enterobacter | Most efficient result |
100 | 78 | 75 | 81 | 93% removal by mix- bacterial strain at dye conc.700 ppm |
300 | 81 | 76 | 83 | 93% removal by mix- bacterial strain at dye conc.700 ppm |
500 | 82 | 85 | 85 | 93% removal by mix- bacterial strain at dye conc.700 ppm |
700 | 91 | 82 | 93 | 93% removal by mix- bacterial strain at dye conc.700 ppm |
900 | 78 | 68 | 75 | 93% removal by mix- bacterial strain at dye conc.700 ppm |
In this study work, sunfix red was decolorized and degraded by using biological degradation. This clearly indicates that decolorization was due to degradation of dyes into interme- diate products. In biological degradation, E.coli, Enterobacter and mix-bacterial strain degraded 90%, 94% & 97% from sun- fix red solution. So that, the ability of the bacterial strains to tolerate, decolorizes and degrade dyes at high concentration & pH gives it an advantage for treatment of textile industry wastewater.
Grand appreciation, gratitude and deep thankfulness goes to International Center for Diarrhoea Disease Research, Bangla- desh (ICDDR,B) for providing the bacterial strains and also to Mr. Rafiqul Islam, Lab Manager, Independent University, Bangladesh to arrange necessary equipment required for this work & for his co-operation & support also.
[1] M. M. Islam, K. Mahmud, O. Faruk, and M. S. Billah “Textile Dyeing Industries in Bangladesh for Sustainable Development“ International Journal of Environmental Science and Development, Vol.2, No. 6, December 2011
[2] A.Tripathi, S.K. Srivastava, “Ecofriendly Treatment of Azo Dyes: Biodecolorization using Bacterial Strains” International Journal of Bios- cience, Biochemistry and Bioinformatics, Vol. 1, No. 1, May 2011
[3] http://www.dequim.com/catalogos/sunfixspd.pdf
[4] http://www.chm.davidson.edu/vce/spectrophotometry/UnknownSol ution
[5] Friedrich Widdel, “Theory and Measurement of Bacterial Growth”,
Grundpraktikum Mikrobiologie, 4. Sem. (B.Sc.), Universität Bremen, 04
May, (2007).
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