Effluent Treatment in Textile Industry-1

The idea for this topic is triggered by the news of discovery of treatment of textile effluent by a combination of biological and physico-chemical methods.

Speaking simply, the effluent control is effected by two approachs, physcial and chemical. However these methods are expensive and non effective. Using both biological and chemical methods, one can achieve effective effluent control. 

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Industrial Textile processing comprises several processes which include pretreatment, dyeing, printing and finishing processes. Besides consuming large amount of energy and water, these processes generate lot of waste products.  

Generally the effluents generated in textile processes have the following shorcomings:

- Heavily Colored

- Contain High concentration of Salts

- Exhibit High BOD ( Biochemical Oxygen Demand) and COD ( Chemical Oxygen Demand)

Understanding COD and BOD

COD is the total measurement of all chemicals in the water that can be oxidised.  BOD is supposed to measure the amount of food ( or organic matter ) that bacteria can oxidise. Permissible limit of COD is 250 to 500 ppm and BOD is 30mg/l.

To explain it further, the microbes present in polluted water consume the dissolved oxygen for respiration and nitrification. These bacteria consume pollutants and then use dissolved oxygen to convert the pollutants into energy. Other bacteria consume ammonia to nitrate a process called nitrification. Please see the pictures here for illustration.

This is important to control COD and BOD as a water high in BOD can deplete oxygen in the receiving waters, causing fish kills and ecosystem damages. Low BOD also helps in further treatment.

A typical textile mills effluent has a pH of 9.8 to 11.8, Total alkalinity as CaCO3 17-22 mg per liter, BOD 760-900 mg/l, COD 1400-1700 mg/l, total solids 6000-7000 mg/liter and total chromium 10-13 mg/l.

Three methods are suggested to reduce pollution

1. Use of new, less polluting technologies

2. Effective Treatment of effluent

3. Recyling waste several times over before discharge. 

The following are the most common causes of generation of effluent wasts in textile industry:

Desizing

In general 50% of the water pollution is due to waste water from desizing. 

Problem with Effluent from Desizing

It has high BOD which renders it unsuitable. 

Solutions to Control

- Using enzymes that degrade starch into ethanol. This can be recovered by distillation

- Using oxidative system like H2O2 that degrade startch to CO2 and Water. 

- Using Electro-oxidation

- Treatment with Mixed activated Sludge system. 

In mixed activated sludge system, microorganisms are introduced which convert carbon in the effluent into suspended solids and carbon dioxide and water. The solids are then separated from the wastewater in the settling tank and then recovered.

As most of the dyes are not biodegradable, this method of using activated sludge is not always successful. 

Mercerisation

Problems:

The effluent has high concentration of NaOH

Solutions:

- Recovering NaOH from waste water using membrane techniques. 

- Use of Zinc Chloride during mercerisation

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Buti and Buta Motifs in Jodhpur Textile Printing

1. Sada:  This motif is used by Bishnoi community of Jodhpur.

2. Oul : This motif is worn by Chaudhari Community.

3. Ankuri : This motif is worn by Kalbelia and Jat Community

4. Makhi : This Motif is used by Choudhary community.

5. Gulbuta : This motif is used by Jain and Choudhary community

6. Kapa: This motif is worn by widows of Rabari Community

7. Bhalka: This motif is ued by Gadiya Luhar community.

8. Jali : This motif is used by Gadiya Luhar community

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Traditional Striped Motifs in Jodhpur Textile Printing

Boriya

Boriya Motif- Used by Mali Kaum in Rajasthan

Ilaicha

Ilaicha Motif- Worn by Sirvi in Rajasthan

Jodhpuri Katar

Jodhpuri Katar- Worn by Rabari Kaum

Makoda

Makoda- Worn by Rabaris

Mehndi

Mehndi Motif- Worn by Sindhi Muslim- Ghagras

Methi

Methi Worn by Choudhari Community in Rajasthan

Nimboli

Nimoli Motif- Used by Choudhary Women in Jodhpur

Phooli

Phooli Worn by Rebari ( Raika) in Rajasthan

Rakhri

Rakhri - Worn by Rebaris in Rajasthan

Rata Katar

Rata Katar- Worn by Sirvis

Sada Chint

Sada Chhint- Worn by Vaishnav

Samundar

Samundar- Worn by Merat Kaum in Rajasthan

All these pictures are courtesy Mr. Chhipa Yasin- who has developed a bed sheet using thirty of these now-forgotten motifs.

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Motifs of Jodhpur Printing- Phetiya ( Fetia, Phetia)

Phetiya is one of the most popular motifs used in block printing in Jodhpur. There are various variations of Phetiya are available. Some of them are as given below:

1. Panihari Phetiya

In this motif, Indigo and Alizarin are prominent Colors. It is a traditional costume of Sirvi ( Chaudhary) Community in Rajasthan. The word Sirvi means share cropper (A sharecropper is a farmer who doesn't own the lands he farms). Sirvi people speak Marwari. The men wear cotton thread around their waist, called bell or dhaga, having eleven knots. They believe that this dhaga symbolizes their community deity Jagadhamba of Rajasthan.

2. Nanna Phetiya

It comprises of natural colors like Indigo, Alum, Haldi and Alizerin. Availability of good water enhances this kind of block printing. It is a favourite among the women in the Choudhari community who carry these prints in their traditional Ghaghras.

3. Genda Phetiya

The genda print is seen mostly in the traditional dresses of Rabari community. Some natural colors like alum or indigo are used in Dabu technique of printing.

4. Gunda Phetiya

The Gunda Phetiya kind of block prints are vividly seen in the traditional attires of the Mali Jat in Rajasthan. Simple yet unique prints with Shades of alizerin and indigo enhance the simplicity of the fabric.

5. Bavliya or Guddi Phetiya

The Bavliya kind of print is mostly seen in the traditional outfits of the women in the Choudhari ( Godwal)  community of Rajasthan. The prints are made with finely carved blocks using natural Colors.

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