Bioremediation of industrial effluent containing reactive dyes

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The treated effluent had no color, BOD less than 30 ppm and COD less than 200 ppm. .... ozone treatment by passing fine bubbles for a period of 1 hr. The BOD ...
INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 5, No 6, 2015 © Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article

ISSN 0976 – 4402

Bioremediation of industrial effluent containing reactive dyes Kamat D. V, Kamat S.D Department of Microbiology, Mithibai College, Vile Parle (W), Mumbai 400 056. [email protected] doi: 10.6088/ijes.2014050100101 ABSTRACT With the rapid industrialization water pollution has become a major problem. Characteristics of industrial effluent depend upon the type of industrial raw material and the output of product. In the present study, 1000 m3 / day effluent from a Textile Industry was successfully treated with the consortia of Microorganisms capable of degrading reactive dyes. The BOD and COD were reduced by 96.37% and 98.16% respectively with the retention time of 72 hrs. The aeration system consisted of diffused air. The MLSS was maintained at 6000 to 8000 ppm. The raw effluent had BOD in the range of 1700 to 1860 ppm while COD was 4500 to 5600 ppm and TDS in the range of 8000 to 10,000 ppm. The extended aeration system gave better results than conventional system. The treated effluent was given one hour ozone treatment to further reduce BOD and COD. The biological treatment reduced the cost of chemical by almost 53% while sludge generation was reduced by 62%. Thereby making it highly economical. The treated effluent had no color, BOD less than 30 ppm and COD less than 200 ppm. Keywords: Bioremediation, textile effluent, Ozonation, BOD, TDS 1. Introduction A rapid pace of industrialization coupled with uncontrolled exploitation of nature has resulted in continuous dumping of industrial waste with hazardous chemicals into the ecosystem. This has resulted in disturbing the delicate ecological balance between living and non living components of the biosphere. Textile industry represents the second largest industrial sector in India. The textile industry is well known for its high water consumption and complex waste water due to the variety of additives and finishing processes. Waste generated in the industry is essentially based on various activities of wet processing of textile. The main cause of generating the effluent is the use of huge volume of water either in the actual chemical processing or during re-processing in preparatory, dyeing, printing and finishing. With increasing interest in process water recycling and tighter regulations on the disposal of dye containing waste waters, segregation and separate treatment schemes are becoming important for textile waste waters with high dye concentrations. The major chemical pollutant present on textile are dyes containing carcinogenic amines, toxic heavy metals, pentachlorophenols, chlorine bleaching, halogen carriers, free formaldehyde, biocides, fire resistant and softeners. The effluent of textile industry is highly colored and disposal of this is waste water into environment can be extremely deleterious. Their presence in the watercourses is aesthetically unacceptable and may be visible at concentration as low as 1 ppm.

Received on April 2015 Published on May 2015

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Reactive dyes are complex organic molecules which are refractory in aerobic treatment systems. Some contain metals such as chromium, zinc, and copper. Direct discharge of such effluents causes formation of toxic aromatic amines under anaerobic conditions in receiving media (Murugesan et al, 2003). Several physico-chemical decolorization techniques have been reported in the past two decades however few have been accepted by the textile industries (O’Neill C et al, 2000). Recent fundamental work has revealed the existence of a wide variety of microorganisms capable of decolorizing an equally wide range of dyes (Gupta et al, 2014) A huge amount of various chemicals such as alum, ferric chloride and hydrochloric acid are used by the textile industries for waste treatment which creates a problem of solid waste management and also increases the overall cost of the waste water treatment. Waste water containing dyes is very difficult to treat since the dyes are recalcitrant molecules resistant to aerobic digestion and stable to light. A synthetic dye in waste water cannot be efficiently decolorized by traditional methods. Hence there is high cost and disposal problem for treating dye waste water on a large scale in the textile industry. Chemical methods include coagulation or flocculation combined with flotation and filtration, precipitation-flocculation with ferric or calcium hydroxide, electro flotation, electro kinetic coagulation, conventional oxidation methods by oxidizing agents, irradiation or electrochemical processes. Recently other emerging techniques such as advanced oxidation processes which are based on the generation of very powerful oxidizing agents such as hydroxyl radicals have been applied with success for the pollutant degradation. Although these methods are efficient for treatment, they are costly and commercially unattractive. The high electrical energy demand and consumption of chemical reagents are common problems. Physical methods widely used include membrane filtration processes such as nanofiltration, reverse osmosis, electro dialysis and adsorption techniques. Limited lifespan of the membranes is a major disadvantage of the filtration processes. A combination of biological and physico-chemical method is therefore an attractive option for the efficient treatment of effluent. Effluent from the textile industry is characterized by high values of BOD, COD, TDS, color and an alkaline pH. The high BOD values can cause oxygen depletion if disposed in an untreated form and the high COD values are toxic to aquatic life. Bioremediation is a sustainable strategy that utilizes the metabolic potential of microorganisms to clean-up contaminated environment. It achieves decomposition of contaminant or immobilization by exploiting the existing metabolic potential of microorganisms with novel catabolic functions derived from selection or by introduction of genes encoding such functions. The goal of bioremediation is to transform organic pollutants into harmless metabolites or mineralize the pollutants to carbon dioxide and water (Alexander 1999). Bioremediation techniques are typically more economical than thermal and physicchemical remediation such as incineration (Cho, 2000). 2. Material and methods Sludge and soil samples were collected from contaminated sites for the isolation of organisms. The enrichment was done in media containing effluent from the textile industry using reactive sulfur dyes. The cultures were acclimatized using 50 to 200 ppm of reactive Kamat D. V, Kamat S.D International Journal of Environmental Sciences Volume 5 No.6 2015

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sulfur dye in the medium. Consortium of microorganisms was prepared by using acclimatized cultures isolated from sludge and soil samples. The organisms were selected on the basis of their ability to degrade reactive sulfur dyes. The effluent from the textile industry using reactive dyes was bluish black in color and had an alkaline pH of 12 to 13. The effluent was tested for the routine parameters such as pH, temperature, BOD, COD, TDS, TSS using standard procedures (APHA, 2007). The effluent samples were bioaugmented by inoculating with acclimatized cultures. The flasks were aerated after adding nitrogen supplement. The samples were withdrawn at intervals of 0, 24, 48, 72 and 96 hrs to check for degradation of the dye. A scale up of the treatment system from laboratory scale to pilot plant scale was done. The flow rate of 1000 liters per day was maintained at the pilot scale. A comparative study with the use of chemicals like hydrochloric acid, Alum, Ferric chloride, polyelectrolyte and NaOCl for primary treatment of before and after bioremediation was done. 3. Result and conclusion 3.1 Isolation and identification of bacteria The various cultures which were enriched from soil samples collected from the contaminated sites and sludge samples from the textile industry were isolated and identified using standard biochemical tests. Based on the morphological, physical and biochemical characters they were identified as Pseudomonas sp, Citrobacter sp, Alkaligenes sp, Arthrobacter sp, Flavobacterium sp, Bacillus cereus, Micrococcus luteus, Serratia marcescens, Bacillus subtilis, Bacillus megaterium, Bacillus circulans. 4. Effluent analysis The following tabulation shows the effectiveness of bioremediation of textile effluent containing reactive sulfur dyes. Table 1: Characteristics of raw effluent Parameter pH BOD COD TDS Color

Observation 12.7 to 13.8 1700 to 1860 ppm 4500 – 5600 ppm 8000 – 10000 Dark Blue

The effluent was neutralized with hydrochloric acid prior to bioremediation to about pH 8.6. After bioremediation with the prepared consortium the following results were obtained. Table 2: Parameters of effluent samples after bioremediation Time in hrs. 0 24 48 72 ( n = 20 samples)

pH 8.6 8.1 7.6 7.6

BOD 1750 450 300 160

COD 5200 1800 365 310

Color Dark Blue Blue Light Blue Light Blue

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The consortia could utilize dye molecule as their sole source of carbon which was evident from the reduction in color visualized by decolorization of the treated effluent. The consortium was able to reduce BOD from 1750 ppm to160 ppm, while COD was reduced from 5200 to the level of 310 ppm. Thus BOD was reduced by 90.85%, while COD was reduced by 94.03% within 72 hrs at the laboratory scale level. The treated effluent was given ozone treatment by passing fine bubbles for a period of 1 hr. The BOD and COD and TDS values were estimated after the treatment. A reduction of 64.5% and 52.83% was further achieved after ozonization. In a study on decolorization and COD reduction of disperse and reactive dyes El-Goharya and coworkers (2009) have reported a 68.2% and 76.3% decrease in COD and BOD respectively using chemical coagulant followed by Sequential Batch Reactor process at a hydraulic retention time of 50 hrs. Encouraged by the laboratory scale level results, a study was conducted with the flow rate of 1000 liters / day i.e. approximately 33 liters / hr was maintained in aeration tank of capacity 2100 liters. The textile effluent was neutralized with hydrochloric acid to a pH of 9.0 prior to bioremediation. Following were the results obtained. The study was conducted for 21 days.

Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Table 3: Inlet Parameters of Effluent pH BOD (ppm) COD (ppm) 9.1 1750 4500 8.9 1700 5100 9.8 1790 4900 8.4 1700 5300 8.9 1684 5210 9.1 1670 4990 9.4 1730 5500 9.8 1755 5100 9.7 1750 4500 9.3 1820 5250 9.8 1830 5370 8.7 1830 5500 9.8 1750 4600 9.5 1835 4590 8.7 1730 5200 8.2 1700 5400 9.2 1860 4500 9.1 1800 4600 8.1 1750 5300 8.8 1700 5400 8.6 1790 4600

Color (ptc) 15600 14000 15000 15300 12000 12500 13000 14000 10000 11000 13000 12000 12500 11500 12500 13000 15000 13000 14000 12000 10000

Table 4: Average values of Inlet parameters of Effluent Inlet Parameters pH BOD COD 1758.28 Average 9.09 5067.14 ppm ppm Kamat D. V, Kamat S.D International Journal of Environmental Sciences Volume 5 No.6 2015

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Standard Deviation

0.0429

Range

Min = 8.1 Max = 9.8

46.54 Min = 1700 ppm Max = 1860 ppm

319.72 Min = 4500 ppm Max = 5600 ppm

Table 5 Aeration Tank Parameters pH BOD (ppm) COD (ppm) 7.7 80 200 7.6 50 160 7.6 60 180 7.4 40 120 7.5 70 130 7.5 65 100 7.6 55 110 7.8 54 140 7.6 60 130 7.7 90 160 7.6 50 110 7.6 60 120 7.5 40 140 7.6 60 120 7.6 50 130 7.7 60 140 7.3 70 110 7.4 30 120 7.5 50 100 7.5 60 150 7.3 40 120

Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Color (ptc) 2800 1800 1900 2000 1500 1700 1650 1750 1300 1400 1600 1500 1700 1520 1610 1600 1500 2000 1900 1500 1300

Table 6: Average values of parameters in aeration tank Aeration Tank Parameters

pH

BOD (ppm)

COD (ppm)

Average

7.55

56.85 ppm

132.85 ppm

Standard Deviation

0.102

10.43

19.72

Range

Min = 7.3 Max = 7.8

Min = 90 ppm Max = 30 ppm

Min = 100 ppm Max = 200 ppm

Day 1 2 3

pH 7.2 7.3 7.2

Table 7: Outlet Parameters BOD (ppm) COD (ppm) 50 160 30 110 35 150

Color (ptc) 2600 1800 1700

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4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

7.4 7.7 7.3 7.6 7.8 7.2 7.1 7.5 7.6 7.3 7.5 7.5 7.6 7.8 7.2 7.4 7.4 7.3

25 35 30 25 27 45 26 27 20 28 24 29 40 22 25 24 22 35

100 105 95 110 115 125 95 110 110 90 120 125 100 100 90 110 105 105

Table 8: Average values of outlet parameters Outlet parameters pH BOD ppm Average 7.42 29.71 Standard Deviation 0.17 5.93 Range

Min = 7.1 Max = 7.8

Min = 20 ppm Max = 50 ppm

1800 1400 1650 1300 1300 1300 1550 1450 1600 1500 1600 1500 1200 1800 1700 1500 1200 1400

COD ppm 110.95 12.31 Min = 90 ppm Max = 160 ppm

Online monitoring of textile effluent treatment has been carried out by Esteves and coworkers (2000). They estimated total oxygen demand, color, pH and dissolved oxygen. Monitoring the physic-chemical and chemical treatment of textile waste water using GC-MS, LC-MS techniques have been reported by Weschenfeldera (2007). A study of dye decolorization in an immobilized laccase enzyme reactor has been reported (Kandelbauer et al, 2004). Table 9: Cost Comparison between bioremediation and Physico-Chemical Treatment Chemical HCl Alum FeCl3 Polyelectrolyte NaOCl Total

Quantity Used in PhysicoChemical method 3 tons 1 ton 10 kg 1 kg 40 kg

Cost (Rs) 30,000/0 6000/350/400/720/37470/-

Quantity After Bioremediation 1.40 tons 250 kg 2 kg 0.4 kg 40 kg

Cost (Rs) 15000/1500/70/100/720/17390/-

When only Physico-chemical treatment was given to the raw effluent a lot of expenditure was incurred in chemicals and disposal of sludge. The cost on chemical came down by almost 53% while sludge generation was reduced by 67%. In the entire textile industry the conventional chemical treatment to remove the color, suspended solids, COD etc. in the primary treatment of the ETP makes use of lime and ferrous sulphate. These chemicals used in the conventional treatment come out as hazardous solid waste. Kamat D. V, Kamat S.D International Journal of Environmental Sciences Volume 5 No.6 2015

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This study documents the successful application of bioremediation as a treatment strategy for textile effluent containing reactive sulfur dyes. It also indicates the possibility of the effective use of microorganisms as an economical and environment friendly option to the costly and unecofriendly physico-chemical alternative. Ozonization after bioremediation further reduces BOD and COD. The treated effluent can be discharged in the water bodies as it complies with the MPCB guidelines. The values for safe disposal of effluent are BOD less than 30 ppm and COD less than 250 ppm after the final treatment. 5. References 1.

Alexander M., (1999), Bioremediation in the rhizosphere. Environmental science technology, 27 pp 2630–2636.

2. APHA, (2007), Standard methods for examination of water and waste water. 20th edition. American Public Health Association, Washington DC. 3. Cho Y G., (2000), Decolorization of textile dyes by newly isolated bacterial strains. J. of Biotechnology, 101(1), pp 57–68. 4. El-Goharya F Tawfik A., (2009), Decolorization and COD reduction of disperse and reactive dyes waste water using chemical coagulation followed by sequential batch reactor process. Desalination, 249(3) pp 1159–1164, 5. Esteves S R, Wilcox S J, O’Neill C, Hawkes F R and Hawkes D L., (2000), Online Monitoring of Anaerobic-Aerobic Biotreatment of textile effluent. Environmental Technology. 21(8), pp 927–936. 6. Gupta P, Kumar A, Khatri A and Asthana M., (2014), Acid green dye decolorizing bacteria from Yamuna water and textile effluents. International Journal of Environmental Sciences. 5(3), pp 482–490. 7. Kandelbauer A, Oliver M, Rudolf W and Gubitz G., (2004), Study of dye reduction in an immobilized laccase enzyme bioreactor. Biotechnology and Bioengineering, 87(4), pp 552 – 563. 8. Murugesan K and Kalaichelavan P. T., (2003), Synthetic dye decolorization by white rot fungi. Indian. Journal of Experimental. Biology, 41, pp 1076 – 1087. 9. O’Neill C, Hawkes F R, Hawkes D L, Esteves M S and Wilcox S J., (2004), Anaerobic – aerobic bio treatment of simulated textile effluent containing varied ratios of starch and azo dye. Water Research, 34(8), pp 2355-2361. 10. Weschefeldera S E, Josa H J, Gebhardtb H and Schroderb W., (2007), Monitoring the

Physico-chemical and chemical treatment of textile wastewater using GC/MS, LC/MS techniques. Separation Science and Technology, 42(7), pp 1535 – 1551.

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