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Seminar on

Decolourization of Texti le Dye Effluents

by

Shameembanu A. Shameembanu A. ByadgiByadgi

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Water is the main component used in all type of industries

Water used for different processes is not completely utilized & is

discharged as wastewater

Introduction

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Textile industry is one of the biggest consumer of potable water as well

as chemicals used during textile processing stages

Dyeing & finishing stages are the major producer of wastewater with

complex characteristics

The unused dyes & chemicals are discharged as dye effluents from

various units Dyeing

Bleaching

Wet finishing

Scouring Neutralizing

Desizing

Mercerizing

Printing

Others

Carbonizing

Fueling

85%

62%

58%

52%

33%

21%

13%

10%

4%

2%

2%

Composition of textile dye effluents

Parameters Permissible limit

pH 6.5 – 8.5

Biochemical Oxygen Demand (mg/L) 100 – 300

Chemical Oxygen Demand (mg/L) 150 – 250

Total Suspended Solids (mg/L) 100 – 600

Total Dissolved Solids (mg/L) 500 – 2000

Chloride (mg/L) 250 – 1000

Total Nitrogen (mg/L) 70 – 100

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Dye effluents

Plant species

Aquatic animals

Human beings

Environment

Interrupt photosynthesis activity Decreases soil quality Affects plant growth

Increased level of danger to life of aquatic animals

Hazardous diseases Carcinogenic

Increase aqueous toxicity, COD & BOD

Effects of dye effluents

Textile wastewater is highly coloured

Contain heavy metals that are complex compounds

Cause high electrolyte and conductivity concentrations in the dye

wastewater leading to acute and chronic toxicity problems

Discolour water bodies and increase BOD of the contaminated water

Carcinogenic, mutagenic and generally very harmful to the

environment

Need for dye effluent treatment

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Decolourization techniques

Physical treatment

Chemical treatment

Physico-chemical treatment

Biological treatment

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Physical Treatment

………removal of substances by use of naturally occurring forces, such as

gravity, electrical attraction, and van der Waal forces, as well as by use of

physical barriers

Adsorption

efficient in the removal of pollutants

result of two mechanisms: adsorption & ion exchange

influenced by many physico-chemical factors, e.g., sorbent surface area,

particle size, pH, contact time

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Methods

Activated carbon

most commonly used method

effective for adsorbing cationic, mordant & acid dyes, disperse, direct,

vat, pigment and reactive dyes

performance depends on the type of carbon used and the characteristics

of wastewater

Membrane filtration

can clarify, concentrate and separates dye from effluent

exhibit special features like resistance to temperature, adverse chemical

environment and microbial attack

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Investigation on the removal of direct red dye using Aspergillus niger and Aspergillus flavus under static

and shaking conditions with modeling

Mohan et. al., 2012Tamil Nadu

Objective:

To investigate the potential of fungal cultures for decolourization

of synthetic textile dyes 10

Decolourization of dyes

Direct red dyes mixed in 100 ml synthetic water at different concentrations (50, 100 and 200 mg/L)

Isolated organisms in the solution

Incubate

Static condition Shaker (37ºC and pH7) (150 rpm, 37ºC, pH 7)

OD values measured at maximum absorbance values of each dye at 24 th, 48th, 72nd and 96th hr

Inoculate

Methodology

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% decolourization = OD value for control – OD value for sample

OD value for Control

Average decolourization = C x % D x 1000

100 x t

C = initial concentration of dye (mg/l) % D = dye decolourization (%) t = time

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Results and Discussion

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Figure 1. Decolourization of Direct red by A.niger at static conditions

Figure 2. Decolourization of Direct red by A.niger at 150 rpm

Figure 3. Decolourization of Direct red by A.flavus at

static conditions

Figure 4: Decolourization of Direct red by A.flavus at 150 rpm

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Conclusion

Isolated organisms, Aspergillus niger and Aspergillus flavus have the ability to decolorize the direct red dye

Aspergillus niger decolourizes the dyes in static condition potentially where as A.flavus decolourizes at shaking growth condition

The study brings out the ability of Aspergillus sp. to degrade direct dyes and reinforces the potential of these fungi for the decolourization of textile effluents

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Chemical Treatment

Chemicals are used in an array of processes to expedite

disinfection

Used alongside biological and physical cleaning processes to

achieve various water standards

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Ozonation

A good oxidizing agent

The dosage applied is dependent on the total colour and residual COD

to be removed

Oxidative process

commonly used method for decolourization by chemical means

main oxidizing agent used is hydrogen peroxide

removes the dye effluent by oxidation in aromatic ring cleavage of the

dye molecules

Methods

Fenton reagent

suitable for the treatment of effluents which are resistant to biological

treatment or poisonous to live biomass

Performance depends on good flock formation and settling quality

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Photo chemical process

Degrades dye molecules into carbon dioxide and water by UV

treatment

Degradation is caused by the production of high concentrations of

hydroxyl radicals

The rate of removal is influenced by the intensity of UV radiation, pH,

dye structure and the dye bath composition

Decolourization and removal of COD and BOD from raw and biotreated textile dye bath effluent through

advanced oxidation processes (AOPS)

Muhammad et. al., 2008Lahore, Pakistan

Objective:

To study the effect of advanced oxidation processes (AOPs) on

decolourization of raw and biotreated textile dye bath effluents

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Methodology

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Table 1. Characterization of raw and biotreated textile dye bath effluent

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*Absorbance of colour at 465nm

Parameters Raw Biotreated

COD (mg/l) 750 154

A* (Colour) 1.8 1.2

BOD (mg/l) 261 76.2

pH (units) 12.1 8.4

Figure 5. Comparison of AOPs in terms of COD, color & BOD removal of raw textile effluent

Results and Discussion

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Figure 6. Biodegradability improvement of raw textile effluent

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Figure 7. Comparison of AOPs in terms of (%) removal of COD, color & BOD of biotreated textile effluent

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Figure 8. Biodegradability improvement of biotreated textile effluent

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Conclusion

The application of a combined method i.e., biotreatment and AOPs for treating dye bath effluent was advantageous

The combined approach allowed better achievement of decolourization efficiency and reduced treatment costs

Application of AOPs to biotreated textile effluent was more effective

than raw effluent

Ozonation process for raw textile effluent was better for decolourization than the AOPs applied

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Decolourization of Textile dye waste waters by Hydrogen peroxide, UV and Sunlight

Dinarvand, 2014Iran

Objective:

To investigate the efficiency of decolourization of the azo dye

with UV radiation in the presence of H2O2

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Methodology

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Figure 9. UV radiation constructed reactor box

Ultraviolet radiation treatment

Specifications

60 x 40 x 30 cmUV lamp of 30WRadiation wavelength 254nm

Solar radiation treatment

Quartz tubes with 3mL of wastewater

Placed at 45º angle

Exposed to sunshine (12pm – 4pm)

Assessed for colour removal

Results and Discussion

Figure 10. Decolourization by UV irradiation in the absence of H2O2

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Figure 11. Decolourization by UV irradiation in the presence of H2O2

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Figure 12. Decolourization by UV radiation at pH 7 with different concentrations of H2O2

Optimum operating conditions of Solar light/H2O2

In the presence of 0.143M H2O2 solution, maximum of 97%

decolourization at pH 4 and minimum of 40% decolourization at pH 10

was achieved after 90 minutes

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Conclusion

Decolourization percentage with UV radiation at 60 minutes in presence of 0.014M H2O2 at 50°C temperature was 99.8

The presence of 0.143M of hydrogen peroxide caused maximum per cent decolourization (97%) in case of solar light/H2O2

It was suggested that the decolourization of dye DB-177 should be performed in the presence of ultraviolet radiation

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Physico-chemical Treatment

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Methods

Sedimentation

Removal of floc by solid-liquid separation

Achieved by using low, medium and high rate settlers

The rate is determined by the speed at which water and sludge are separated

Coagulation

Destabilization or neutralization of negative charges in the wastewater by

addition of coagulant during rapid mixing and very short contact time

The quantity of coagulant applied depends on the quality of water

Commonly used coagulants are ferric chloride, ferric sulphate, aluminium

sulphate, lime, etc

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Flocculation

Referred to formation of flocs and bridges

Previously formed flocs group together, increase in volume and density,

later gets sedimented

Achieved by applying a gradient and contact time varying between 15

minutes and 3 hours

Removal of reactive yellow dye from aqueous solutions by using natural coagulant (Moringa oleifera)

Veeramalini et. al., 2012Chennai, India

Objective:

To examine the decolourization of the Reactive Yellow 145 dye

by Moringa oleifera under static conditions

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Methodology

Preparation of coagulant

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Coagulation study (Jar test)

1000ml dye solution

Add coagulant with rapid mixing at 100rpm for 2 min

Slow mixing at 40rpm for 30 min

Kept for sedimentation for 30 min

Filtered using Whatman filter paper

Analyzed for colour removal

Results and Discussion

Figure 13: Effect of coagulant dose on the removal of colour

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Figure 14: Effect of contact time on decolourization

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Figure 15. Effect of pH on decolorization of Reactive yellow dye by M.oleifera

Conclusion

100mg Moringa oleifera gave approximately 95% COD reduction

after10 minutes contact time while 500mg M.oleifera reduced colour by

90% at pH 10

100mg coagulant enhances efficient removal of COD and colour in the

coagulation process

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Decolourization and COD reduction efficiency of magnesium over iron based salt for the treatment of textile

wastewater containing diazo and anthraquinone dyes

Verma et. al., 2012Odisha, India

Objective:

To investigate the effectiveness of MgCl2 & FeSO4 for

decolourization and COD reduction

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Methodology

Materials usedConcentration

(mg/L)Function

Starch 1000 Sizing agent

Acetic acid 200 Sizing agent

Sucrose 600 Sizing agent

Dyes 200 Colouring agent

NaOH 500 Hydrolysing agent

H2SO4 300 pH neutralization

Na2CO3 500 Fixing agent

NaCl 3000 Fixing agent

Sodium lauryl sulphate 100 Scouring agent

Table 2. Chemical constituents used for the preparation of synthetic textile wastewater

Optimum coagulant dosage: Determined by Jar test

COD reduction: COD was analysed as per closed reflux colourimetric method

Removal (%) = (Aut – At) x 100

Aut

Aut & At = absorbencies of untreated and treated wastewater samples

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Results and Discussion

Figure 16a. Colour removal (%) & COD reduction of textile wastewater containing RB5 (Reactive Black 5)

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Figure 16b. Colour removal (%) & COD reduction of textile wastewater containing CR (Congo Red)

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Figure 16c. Colour removal (%) & COD reduction of textile wastewater containing DB3 (Disperse Blue 3)

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Figure 16d. Colour removal (%) & COD reduction of textile wastewater containing RB5+CR

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Figure 16e. Colour removal (%) & COD reduction of textile wastewater containing CR+DB3

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Figure 16f. Colour removal (%) & COD reduction of textile wastewater containing RB5+DB3

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Figure 16g. Colour removal percentage for textile wastewater containing RB5+CR+DB3

Conclusion

MgCl2 in combination with lime was superior over the other coagulants

for decolourization & COD reduction

More than 99% decolorization efficiency & 63% COD reduction

efficiency was observed using MgCl2/Lime as coagulants

MgCl2/Lime can be used as an efficient coagulant system for the

treatment of textile wastewater

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Biological Treatment

Remove dissolved organics from effluent and thus reduce chemical

and biological oxygen demands of the effluents

Achieved biologically wherein bacteria/fungi are used to convert the

colloidal and dissolved carbonaceous organic matter into various gases

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Methods

Aerobic Treatment

Dissolved oxygen is utilized by microorganism and finally wastes are

converted into biomass and carbon dioxide

Organic matter is partially oxidized and some of the energy produced is

used for generating new living cells under the formation of flocs

Bacteria and fungi have been most widely studied for their capability to

remediate textile and dye wastewaters

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Anaerobic treatment

Involves an oxidation-reduction reaction with hydrogen rather than free

molecular oxygen aerobic system

Dyes are degraded and converted into aromatic amines, later the

produced aromatic amines are degraded by aerobic biodegradation

Evaluation of microbial systems for biotreatment of textile waste effluents in Nigeria: Biodecolourization

and biodegradation of textile dye

Agarry and Ajani, 2011Nigeria

Objective:

To evaluate the remediation potential of isolated micro organisms

to decolourize the dye and reduce the COD & BOD of textile effluents

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Methodology

Micro organismsBacterial species Pseudomonas fluorescence Pseudomonas nigificansPseudomonas gellucidium

Fungal species Aspergillus niger Fusarium compacticumProteus morganii

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Batch microbial treatment

Autoclaved mineral salt medium (0.8L) + 3L textile waste effluent in a bioreactor

Add inoculum (200ml) aseptically to make 4L working solution

Stir at room temperature with agitation speed of 300 rpm

Ferment for 14 days

Filter the solution through Whatman paper No. 1 & centrifuged for 10 minutes

Analysis of decolourization, COD & BOD

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% decolourization = A – B x 100 A

A = Initial absorbance B = Final absorbance

Determination of COD & BOD

COD – standard colourimetric method (APHA – AWWA, 1985)

BOD – 5 day BOD test

Determination of decolourization percentage

Results and Discussion

Figure 17. Decolourization of textile waste effluents by isolated microbial species[A = P.flourescence, B = P.nigificans, C = P.gellucidium, D = A.niger, E = P.morganii,

F = F.compacticum]

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Order of percent dye decolourization A. niger > P. fluorescence > P. morganii > F. compacticum > P. nigificans > P. gellucidium

Figure 18. COD reduction of textile waste effluents by isolated microbial species [A = P.flourescence, B = P.nigificans, C = P.gellucidium, D = A.niger,

E = P.morganii, F = F.compacticum]

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Figure 19. BOD reduction of textile waste effluents by isolated microbial species [A = P.flourescence, B = P.nigificans, C = P.gellucidium, D = A.niger,

E = P.morganii, F = F.compacticum]

Figure 20. Effect of dye concentration on decolourization by binary mixed culture of P.fluorescence and A.niger

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Conclusion

Aspergillus niger, Pseudomonas fluorescence, Proteus morganii,

Fusarium compacticum, Pseudomonas nigificans & Pseudomonas

gellucidium have a significant potential for dye decolourization and

degradation

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Biological treatment of azo dyes and textile industry effluent by newly isolated White rot fungi

Schizophyllum commune and Lenzites eximia

Selvam and Shanmuga, 2012Coimbatore

Objective:

To study the dye decolourization of azo dye and textile industry

effluent treatment by White rot fungi in batch and continuous mode66

Methodology

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Decolourization of azo dyes

C-limited medium containing congo red, methylorange & erichrome black-T

(each 50µM)

Spore suspension of S.commune & L.eximia

Rotary shaker (120rpm) at 39ºC for 6 days

Filtered through G3 sintered glass filter

Decolourization of textile industry effluent

C-limited medium containing textile dye effluent (950ml)

50ml of spore suspension (105 spore/ml) of S.commune & L.eximia

Maintained at 39ºC for 6 days

Analysed for colour removal

Inoculate Inoculate

Incubate

Results and Discussion

Figure 21. Removal of Azo dyes from aqueous solution by Schizophyllum commune

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Figure 22. Removal of Azo dyes from aqueous solution by Lenzites eximia 69

Figure 23. Colour removal of textile industry effluent by Schizophyllum

commune

Figure 24. Colour removal of textile industry effluent by

Lenzites eximia

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Conclusion

Schizophyllum commune was more efficient than Lenzites eximia for the

treatment of azo dyes and textile dye industry effluent in both batch

mode and continuous mode

The batch mode treatment of textile industry effluents by Schizophyllum

commune was more efficient when compared to continuous mode

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Summary

Conventional technologies to treat textile wastewater include

combinations of biological, physical and chemical methods, but require

high capital and operating costs

Biological treatments can efficiently remove dyes from large volumes

of wastewater at low cost

Need of the day is to substitute hazardous chemicals by using

environment friendly methods

Best approach to reduce wastewater discharge is to manufacture eco-

friendly products and to modify certain areas of textile processing in

to avoid toxicity

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“Better handling of textile waste and their efficient disposal will surely be an appropriate step to maintain ecological

balance on earth”