Report Ishita Kumar

8/12/2019 Report Ishita Kumar

1/42

1

A Project Report on

Optimization of Coagulant Blends for DyeWastewater Colour Removal

Under the Supervision of

Dr. Tarun. K. Bera

Senior Chemist, NLC Nalco India Ltd, Pune

Undertaken by

Ishita Kumar

3rdYear, B.E Environmental EngineeringDelhi Technological University, DTU

Formerly known as Delhi College of Engineering, DCE
http://www.google.com.sg/imgres?imgurl=http://aglasem.com/updates/wp-content/uploads/2011/05/Delhi-Technological-University.jpg&imgrefurl=http://aglasem.com/updates/?p=7575&usg=__Ti5hVcHhEAAGUHsFftFpB6G03t4=&h=199&w=200&sz=12&hl=en&start=14&zoom=1&itbs=1&tbnid=4n5kDa1cTqRkiM:&tbnh=103&tbnw=104&prev=/search?q=delhi+technological+university&hl=en&safe=active&biw=1260&bih=638&gbv=2&tbm=isch&ei=7WgmTqqGBYjsrQfUqtyPCQhttp://www.google.com.sg/imgres?imgurl=http://aglasem.com/updates/wp-content/uploads/2011/05/Delhi-Technological-University.jpg&imgrefurl=http://aglasem.com/updates/?p=7575&usg=__Ti5hVcHhEAAGUHsFftFpB6G03t4=&h=199&w=200&sz=12&hl=en&start=14&zoom=1&itbs=1&tbnid=4n5kDa1cTqRkiM:&tbnh=103&tbnw=104&prev=/search?q=delhi+technological+university&hl=en&safe=active&biw=1260&bih=638&gbv=2&tbm=isch&ei=7WgmTqqGBYjsrQfUqtyPCQ


2/42

2

Abstract

Sedimentation aided with Coagulation and Flocculation was employed for the

treatment of high concentration reactive dye wastewater. An organic polymer

coagulant based on Cyanoguanidine and formaldehyde namely N-8123 was

blended with inorganic coagulants such as PolyAluminium Chloride (133L), Ferric

Chloride (FeCl3) , Ferrous Sulphate (FeSO4) etc. in order to carry out colour-

removal study. The anionic flocculant N-9901 was used for the dye wastewater

treatment. Optimization studies were conducted on synthetic dye wastewater

prepared using 100ppm cotton blue dye as well as the real industrial wastewater

from Huntsman Ltd and Merchem Ltd. However, the required dosage of FeCl 3 and

N-8123 blend was higher compared to 133L & N-8123 blend to achieve similar

colour removal. The effect of pH on colour removal was also conducted using

synthetic dye wastewater. The studies conducted on industrial wastewater

sample from Huntsman Ltd. showed a colour removal performance of 92% using

an optimized blend of FeSO4and N-8123 and that for Merchem Ltd was found to

be the ZnCl2and N-8123 blend.

Keywords: Coagulation; Dye Wastewater; Dye; Polymer


3/42

3

Acknowledgement

I would like to offer my sincere gratitude to Hari Reddy for giving me an

opportunity to work in a world-class organization. I also wish to thank

Vaideeswaran Sivaswamy and Divagar Lakshmanan for their constant support and

encouragement during the course of my internship programme. I owe thanks to

Gaurav Garg and Bhumika Kadam for their help and advice which came across as

a great help. I offer deep gratitude to my mentor Dr. Tarun.K. Bera for enhancing

my knowledge and expertise in the field of wastewater. His consistent

encouragement and feedback helped me to successfully complete my project. I

also owe a great deal of my knowledge to Trishul Artham as he stood by me in the

formative period of the internship.

I also wish to thank all the colleagues in Nalco for being a great support system.

The lab personnel and support staff were a great help while working in the lab.

Last but not the least; I would like to thank my fellow interns for the wonderful

time and a memorable experience.

Ishita Kumar

3rdYear, B.E Environmental Engineering

Delhi Technological University (DTU) (formerly)

Delhi College of Engineering, DCE


4/42

4

Certificate

This is to certify that the project entitled Optimization of Coagulation Blends on

Dye Wastewater Colour Removal undertaken by Ishita Kumar, 3rdYear, B.E

Environmental Engineering has been successfully completed in 8 weeks under the

supervision of Dr. Tarun. K. Bera, Senior Chemist working at NLC Nalco Ltd, PUNE

R&D, India.

Dr. Tarun. K. Bera

Senior Chemist

NLC, Nalco Ltd, Pune R&D, India


5/42

5

Contents

1. Introduction ................................................................................................................................ 7

1.1 Textile Industry Processes ..................................................................................................... 7

1.1.1 Yarn Formation ............................................................................................................... 7

1.1.2 Fabric Formation............................................................................................................. 7

1.1.3 Wet Processing ............................................................................................................... 8

1.1.4 Fabric Preparation .......................................................................................................... 8

1.2 Dyes: Definition and Types .................................................................................................. 11

1.2.1 Types of Synthetic Dyes ................................................................................................ 11

1.3 Textile Waste Streams ......................................................................................................... 14

1.3.1 Wastewater .................................................................................................................. 14

1.3.2 Metal Toxicity ............................................................................................................... 18

1.3.3 Aquatic Toxicity ............................................................................................................ 18

1.3.4 Air Emissions ................................................................................................................. 18

1.3.5 Other Wastes ................................................................................................................ 19

2. Existing Nalco Program for Colour Removal ............................................................................. 20

3. Objective and Scope of the Project .......................................................................................... 21

4. Experimental Section ................................................................................................................ 22

4.1 Testing Procedure ............................................................................................................... 22

4.1.1 Jar Testing Method ....................................................................................................... 22

4.1.2 Measurement of True Colour ....................................................................................... 22

4.1.3 Turbidity Measurement ................................................................................................ 22

4.1.4 COD Measurement ....................................................................................................... 23

4.2Polymer Make-up Procedure ............................................................................................... 23

4.3Coagulant Make-Up Procedure ............................................................................................ 24

4.4 pH Measurement ................................................................................................................ 24

TDS Measurement ..................................................................................................................... 24

5. Results and Discussion .............................................................................................................. 25

5.1 Variation of Dye Concentration with Optimum Coagulant Dose........................................ 25

5.2 Dosage Optimization of N-8123 on 100 ppm Cotton Blue Dye. ......................................... 25


6/42

6

5.3 Dosage Optimization of 133L Dose on 100 ppm Cotton Blue Dye Solution. ...................... 27

5.4 Dosage Optimization of N-8123 and 133L Blend ................................................................ 28

5.5 Optimization of FeCl3 Dose on 100 ppm Cotton Blue Dye .................................................. 30

5.6 Optimization of a blend of Ferric Chloride (FeCl3) and N-8123 on 100 ppm Cotton Blue

Dye............................................................................................................................................. 32

5.7 Industrial Wastewater Testing ............................................................................................ 33

5.7.1 Industrial Sample 1 ....................................................................................................... 33

5.7.2. Industrial Sample 2 ...................................................................................................... 36

6.Conclusion .................................................................................................................................. 39

7.Future Directions ....................................................................................................................... 41

8.References ................................................................................................................................. 42


7/42

7

1. Introduction

The textile industry is comprised of a diverse, fragmented group of establishments that produce

and or process textile-related products (fiber, yarn, fabric) for further processing into apparel,

home furnishings, and industrial goods. Textile establishments receive and prepare fibers;

transform fibers into yarn, thread, or webbing; convert the yarn into fabric or related products;

and dye and finish these materials at various stages of production. The process of converting

raw fibers into finished apparel and non-apparel textile products is complex; thus, most textile

mills specialize. Little overlap occurs between hitting and weaving, or among production of

manmade, cotton, and wool fabrics. The primary focus of this section is on weaving and knitting

operations, with a brief mention of processes used to make carpets. In its broadest sense, the

textile industry includes the production of yarn, fabric, and finished goods. This section focuses

on the following four production stages, with a brief discussion of the fabrication of non-

apparel goods:

1.1 Textile Industry Processes

1.1.1 Yarn Formation

Textile fibers are converted into yarn by grouping and twisting operations used to bind them

together. Natural fibers, known as staple when harvested, include animal and plant fibers, such

as cotton and wool. These fibers must go through a series of preparation steps before they can

be spun into yarn, including opening, blending, carding, combing, and drafting.

1.1.2 Fabric Formation

The major methods for fabric manufacture are weaving and knitting. Weaving, or interlacing

yarns, is the most common process used to create fabrics. Weaving mills classified as broad

woven mills consume the largest portion of textile fiber and produce the raw textile material

from which most textile products are made. Narrow woven, nonwovens, and rope are also

produced primarily for use in industrial applications.

Starch, the most common primary size component, accounts for roughly two-thirds of all size

chemicals used in the U.S. (130 million pounds per year). Starch is used primarily on natural

fibers and in a blend with synthetic sizes for coating natural and synthetic yarns. Polyvinylalcohol (PVA), the leading synthetic size, accounts for much of the remaining size consumed in

the U.S. (70 million pounds per year). PVA is increasing in use since it can be recycled, unlike

starch. PVA is used with polyester cotton yarns and pure cotton yarns either in a pure form or in

blends with natural and other synthetic sizes. Other synthetic sizes contain acrylic and acrylic

copolymer components. Semisynthetic sizes, such as carboxymethyl cellulose (CMC) and

modified starches are also used. Knitting is the second most frequently used method of fabric


8/42

8

construction. Manufacturers of knit fabrics also consume a sizeable amount of fibers. Knitted

fabrics can be used for hosiery, underwear, sweaters, slacks, suits, coats, rugs, and other home

furnishings.

1.1.3 Wet Processing

Woven and knit fabrics cannot be processed into apparel and other finished goods until thefabrics have passed through several water-intensive wet processing stages. Wet processing

enhances the appearance, durability, and serviceability of fabrics by converting undyed and

unfinished goods, known as gray or greige goods, into finished consumers goods. Also

collectively known as finishing, wet processing has been broken down into four stages in this

section for simplification: fabric preparation, dyeing, printing, and finishing. These stages

involve treating gray goods with chemical baths and often require additional washing, rinsing,

and drying steps. Note that some of these steps may be optional depending on the style of

fabric being manufactured.

In terms of waste generation and environmental impacts, wet processing is the most significanttextile operation. Methods used vary greatly depending on end-products and applications, site

specific manufacturing practices, and fiber type. Natural fibers typically require more

processing steps than manmade fibers. For most wool products and some manmade and cotton

products, the yarn is dyed before weaving; thus, the pattern is woven into the fabric. Processing

methods may also differ based on the final properties desired, such as tensile strength,

flexibility, uniformity, and luster (Snowden-Swan, 1995).

Most manufactured textiles are shipped from textile mills to commission dyeing and finishing

shops for wet processing, although some forms have integrated wet processing into their

operations. A wide range of' equipment is used for textile dyeing and finishing (EPA, 1996).Much of the waste generated from the industry is produced during the wet processing stages.

Relatively large volumes of wastewater are generated, containing a wide range of contaminants

that must be treated prior to disposal. Significant quantities of energy are spent heating and

cooling chemical baths and drying fabrics and yarns (Snowden-Swan, 1995).

1.1.4 Fabric Preparation

Most fabric that is dyed, printed, or finished must be first prepared, with the exception of

denim and certain knit styles. Preparation, also known as pretreatment, consists of a series of

various treatment and rinsing steps critical to obtaining good results in subsequent textile

finishing processes. In preparation, the mill removes natural impurities or processing chemicals

that interfere with dyeing, printing, and finishing. Typical preparation treatments include

desizing, scouring, and bleaching.

Singeing: If a fabric is to have a smooth finish, singeing is essential. Singeing is a dry processused on woven goods that removes fibers protruding from yarns or fabrics. These are

burned off by passing the fibers over a flame or heated copperplates. Singeing improves the


9/42

9

surface appearance of woven goods and reduces pilling. Pollutant outputs associated with

singeing include relatively small amount of exhaust gases from the burners.

Desizing: It is an important preparation step used to remove size materials applied prior toweaving. Manmade fibers are generally sized with water-soluble sizes that are easily

removed by a hot-water wash or in the scouring process. Natural fibers such as cotton aremost often sized with water-insoluble starches or mixtures of starch and other materials.

Enzymes are used to break these starches into water-soluble sugars, which are then

removed by washing before the cloth is scoured. Removing starches before scouring is

necessary because they can react and cause color changes when exposed to sodium

hydroxide in scouring.

Scouring: It is a cleaning process that removes impurities from fibers, yarns, or cloththrough washing. Alkaline solutions are typically used for scouring; however, in some cases

solvent solutions may also be used. Scouring uses alkali, typically hydroxide, to break down

natural oils and surfactants and to emulsify and suspend remaining impurities in thescouring bath. The specific scouring procedures, chemicals, temperature, and time vary with

the type of fiber, yarn, and cloth construction. Impurities may include lubricants, dirt and

other natural materials, water-soluble sizes, antistatic agents, and residual tints used for

yarn identification. Typically, scouring wastes contribute a large portion of biological oxygen

demand (BOD) loads from preparation processes (NC DEHNR, 1986).

Bleaching: Bleaching is a chemical process that eliminates unwanted colored matter fromfibers, yarns, or cloth. Bleaching decolorizes colored impurities that are not removed by

scouring and prepares the cloth for further finishing processes such as dyeing or printing.

Several different types of chemicals are used as bleaching agents, and selection depends on

the type of fiber present in the yarn, cloth, or finished product and the subsequent finishing

that the product will receive. The most common bleaching agents include hydrogen

peroxide, sodium hypochlorite, sodium chlorite, and sulfur dioxide gas. Hydrogen peroxide

is by far the most commonly used bleaching agent for cotton and cotton blends, accounting

for over 90 percent of the bleach used in textile operations, and is typically used with

caustic solutions. Bleaching contributes less than 5 percent of the total textile mill BOD load

(NC DEHNR, 1986).

Peroxide bleaching can be responsible for wastewater with high pH levels. Because

peroxide bleaching typically produces wastewater with few contaminants, water

conservation and chemical handling issues are the primary pollution concerns.

Mercerizing: Mercerization is a continuous chemical process used for Mercerizing. Mercerization is a continuous chemical process used for cotton and cottod polyester goods

to increase dye-ability, luster, and appearance. This causes the fiber to become more

lustrous than the original fiber, increase in strength by as much as 20 percent, and increase

its affinity for dyes. Mercerizing typically follows singeing and may either precede or follow


10/42

10

bleaching (Corbman, 1975). During mercerizing, the fabric is passed through a cold 15 to 20

percent solution of caustic soda and then stretched out on a tender frame where hot-water

sprays remove most of the caustic solution (Corbman, 1975). After treatment, the caustic is

removed by several washes under tension. Remaining caustic may be neutralized with a

cold acid treatment followed by several more rinses to remove the acid. Wastewater frommercerizing can contain substantial amounts of high pH alkali, accounting for about 20

percent of the weight of goods.

Dyeing Operations: Dyeing operations are used at various stages of production to add colorand intricacy to textiles and increase product value. Textiles are dyed using a wide range of

dyestuffs, techniques, and equipment. Dyes used by the textile industry are largely

synthetic; typically derived from coal tar and petroleum-based intermediates. Dyes are sold

as powders, granules, pastes, and liquid dispersions, with concentrations of active

ingredients ranging typically from 20 to 80 percent.

Dyeing can be performed using continuous or batch processes.

Batch Dyeing:In batch dyeing, a certain amount of textile substrate, usually 100 to 1,000kilograms, is loaded into a dyeing machine and brought to equilibrium, or near equilibrium,

with a solution containing the dye. Because the dyes have an affinity for the fibers, the dye

molecules leave the dye solution and enter the fibers over a period of minutes to hours,

depending on the type of dye and fabric used

Continuous dyeing: In these processes typically consist of dye application, dye fixation withchemicals or heat, and washing. Dye fixation is a measure of the amount of the percentage

of dye in a bath that will fix to the fibers of the textile material. Dye fixation on the fiber

occurs much more rapidly in continuous dying than in hatch dyeing.

Yarn Dyeing: Yarn dyeing is used to create interesting checks, stripes, and plaids withdifferent colored yarns in the weaving process. In yarn dyeing, dyestuff penetrates the

fibers in the core of the yarn. Some methods of yarn dyeing are stock, package, and skein

dyeing.

Stock dyeing: In this process dyes is done using perforated tubes. In package dyeing, spoolsof yarn are stacked on perforated rods in a rack and immersed in a tank where dye is then

forced outward from the rods under pressure. The dye is then pressured back through the

packages toward the center to wholly penetrate the entire yarn. Most carded and combed

cotton used for knitted outerwear is package-dyed.

Skein dyeing: In skein dyeing, yarn is loosely coiled on a reel and then dyed. The coils, orskeins, are hung over a rung and immersed in a dyebath (Corbman, 1975). Skein-dyed yarn

is used for bulky acrylic and wool yarns. Typical capacity for package dyeing equipment is

1,210 pounds (550 kg) and for skein dyeing equipment is 220 pounds (100 kg).


11/42

11

Piece Dyeing: Most dyed fabric is piece-dyed since this method gives the manufacturermaximum inventory flexibility to meet color demands as fashion changes. In terms of

overall volume, the largest amount of dyeing is performed using beck and jig equipment.

Beck dyeing: Beck dyeing is a versatile, continuous process used to dye long yards of fabric.About 1,980 pounds (900 kg) of fabric can be dyed on beck equipment at a time. The fabricis passed in rope form through the dyebath. The rope moves over a rail onto a reel which

immerses it into the dye and then draws the fabric up and forward to the front of the

machine. This process is repeated as long as necessary to dye the material uniformly to the

desired color intensity.

Jig Dyeing: Jig dyeing uses the same procedure of beck dyeing, however, the fabric is heldon rollers at full width rather than in rope form as it is passed through the dye-bath

(Corbman, 1975). This reduces fabric tendency to crack or crease. Jig dyeing equipment can

handle 550 pounds (250 kg) of fabric.

Jet dyeing:Fabric can be jet-dyed (at up to 1,100 pounds (500 kg)) by placing it in a heatedtube or column where jets of dye solution are forced through it at high pressures. The dye is

continually recirculated as the fabric is moved along the tube.

Pad dyeing: Pad dyeing, like jig dyeing, dyes the fabric at full width. The fabric is passedthrough a trough containing dye and then between two heavy rollers which force the dye

into the cloth and squeeze out the excess (Corbman, 1975).

1.2 Dyes: Definition and Types

A dye is acolored substance that has anaffinity to thesubstrate to which it is being applied.

The dye is generally applied in anaqueous solution,and may require amordant to improve the

fastness of the dye on the fiber. Both dyes and pigments appear to be colored because they

absorb some wavelengths oflight more than others. In contrast with a dye, apigment generally

is insoluble, and has no affinity for the substrate. Some dyes can beprecipitated with an inert

salt to produce a lake pigment, and based on the salt used they could be aluminum lake,

calcium lake or barium lake pigments

1.2.1 Types of Synthetic Dyes

Acid dyes arewater-soluble anionic dyes that are applied to fibers such as silk,wool,

nylon and modified acrylic fibers using neutral to acid dye baths. Attachment to the

fiber is attributed, at least partly, to salt formation between anionic groups in the dyes

andcationic groups in the fiber. Acid dyes are not substantive tocellulosic fibers. Most

synthetic food colors fall in this category.
http://en.wikipedia.org/wiki/Colorhttp://en.wikipedia.org/wiki/Chemical_affinityhttp://en.wiktionary.org/wiki/substratehttp://en.wikipedia.org/wiki/Aqueous_solutionhttp://en.wikipedia.org/wiki/Mordanthttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Pigmenthttp://en.wikipedia.org/wiki/Precipitation_(chemistry)http://en.wikipedia.org/wiki/Lake_pigmenthttp://en.wikipedia.org/wiki/Acid_dyehttp://en.wikipedia.org/wiki/Acid_dyehttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Solublehttp://en.wikipedia.org/wiki/Anionichttp://en.wikipedia.org/wiki/Fiberhttp://en.wikipedia.org/wiki/Silkhttp://en.wikipedia.org/wiki/Woolhttp://en.wikipedia.org/wiki/Nylonhttp://en.wikipedia.org/wiki/Acrylic_fiberhttp://en.wikipedia.org/wiki/Cationichttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Cationichttp://en.wikipedia.org/wiki/Acrylic_fiberhttp://en.wikipedia.org/wiki/Nylonhttp://en.wikipedia.org/wiki/Woolhttp://en.wikipedia.org/wiki/Silkhttp://en.wikipedia.org/wiki/Fiberhttp://en.wikipedia.org/wiki/Anionichttp://en.wikipedia.org/wiki/Solublehttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Acid_dyehttp://en.wikipedia.org/wiki/Lake_pigmenthttp://en.wikipedia.org/wiki/Precipitation_(chemistry)http://en.wikipedia.org/wiki/Pigmenthttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Mordanthttp://en.wikipedia.org/wiki/Aqueous_solutionhttp://en.wiktionary.org/wiki/substratehttp://en.wikipedia.org/wiki/Chemical_affinityhttp://en.wikipedia.org/wiki/Color


12/42

12

Basic dyesare water-solublecationic dyes that are mainly applied toacrylic fibers,but

find some use for wool and silk. Usuallyacetic acid is added to the dye-bath to help the

uptake of the dye onto the fiber. Basic dyes are also used in the coloration ofpaper.

Direct dyesorsubstantive dyeing is normally carried out in a neutral or slightlyalkaline

dye-bath, at or nearboiling point,with the addition of eithersodium chloride (NaCl) orsodium sulfate (Na2SO4). Direct dyes are used oncotton,paper,leather,wool, silk and

nylon.They are also used aspH indicators and asbiological stains.

Mordant dyesrequire amordant,which improves the fastness of the dye against water,

light andperspiration.The choice of mordant is very important as different mordants

can change the final color significantly. Most natural dyes are mordant dyes and there is

therefore a large literature base describing dyeing techniques. The most important

mordant dyes are the synthetic mordant dyes, or chrome dyes, used for wool; these

comprise some 30% of dyes used for wool, and are especially useful for black and navy

shades. The mordant, potassium dichromate, is applied as an after-treatment. It is

important to note that many mordants, particularly those in the heavy metal category,

can be hazardous to health and extreme care must be taken in using them.

Vat dyes are essentially insoluble in water and incapable of dyeing fibers directly.

However, reduction inalkaline liquor produces the water solublealkalimetalsalt of the

dye, which, in this leuco form, has an affinity for the textile fiber. Subsequent oxidation

reforms the original insoluble dye. The color of denim is due to indigo, the original vat

dye.

Reactive dyesutilize achromophore attached to asubstituent that is capable of directly

reacting with the fibre substrate. Thecovalent bonds that attach reactive dye to natural

fibers make them among the most permanent of dyes. "Cold" reactive dyes, such as

Procion MX,Cibacron F,andDrimarene K,are very easy to use because the dye can be

applied at room temperature. Reactive dyes are by far the best choice for dyeing cotton

and othercellulose fibers at home or in the art studio.

Disperse dyes were originally developed for the dyeing of cellulose acetate, and are

water insoluble. The dyes are finely ground in the presence of a dispersing agent and

sold as a paste, or spray-dried and sold as a powder. Their main use is to dyepolyester

but they can also be used to dye nylon, cellulose triacetate,and acrylic fibers. In some

cases, a dyeing temperature of 130 C is required, and a pressurized dyebath is used.

The very fine particle size gives a large surface area that aids dissolution to allow uptake

by the fiber. The dyeing rate can be significantly influenced by the choice of dispersing

agent used during the grinding.

Azoicdyeing is a technique in which an insolubleazo dye is produced directly onto or

within the fibre. This is achieved by treating a fiber with both diazoic and coupling

components.With suitable adjustment of dyebath conditions the two components react
http://en.wikipedia.org/wiki/Cationichttp://en.wikipedia.org/wiki/Acrylic_fiberhttp://en.wikipedia.org/wiki/Acetic_acidhttp://en.wikipedia.org/wiki/Paperhttp://en.wikipedia.org/wiki/Substantive_dyehttp://en.wikipedia.org/wiki/Alkalinehttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Sodium_chloridehttp://en.wikipedia.org/wiki/Sodium_sulfatehttp://en.wikipedia.org/wiki/Cottonhttp://en.wikipedia.org/wiki/Leatherhttp://en.wikipedia.org/wiki/Nylonhttp://en.wikipedia.org/wiki/PH_indicatorhttp://en.wikipedia.org/wiki/Staining_(biology)http://en.wikipedia.org/wiki/Mordanthttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Perspirationhttp://en.wikipedia.org/wiki/Potassium_dichromatehttp://en.wikipedia.org/wiki/Vat_dyehttp://en.wikipedia.org/wiki/Vat_dyehttp://en.wikipedia.org/wiki/Alkaline_liquorhttp://en.wikipedia.org/wiki/Alkalihttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Salthttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Reactive_dyeshttp://en.wikipedia.org/wiki/Reactive_dyeshttp://en.wikipedia.org/wiki/Chromophorehttp://en.wikipedia.org/wiki/Substituenthttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Covalenthttp://en.wikipedia.org/wiki/Procion_MXhttp://en.wikipedia.org/w/index.php?title=Cibacron_F&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Drimarene_K&action=edit&redlink=1http://en.wikipedia.org/wiki/Cottonhttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Cellulose_acetatehttp://en.wikipedia.org/wiki/Polyesterhttp://en.wikipedia.org/wiki/Cellulose_triacetatehttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Celsiushttp://en.wikipedia.org/wiki/Azo_compoundhttp://en.wiktionary.org/wiki/componenthttp://en.wiktionary.org/wiki/componenthttp://en.wikipedia.org/wiki/Azo_compoundhttp://en.wikipedia.org/wiki/Celsiushttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Cellulose_triacetatehttp://en.wikipedia.org/wiki/Polyesterhttp://en.wikipedia.org/wiki/Cellulose_acetatehttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Cottonhttp://en.wikipedia.org/w/index.php?title=Drimarene_K&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Cibacron_F&action=edit&redlink=1http://en.wikipedia.org/wiki/Procion_MXhttp://en.wikipedia.org/wiki/Covalenthttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Substituenthttp://en.wikipedia.org/wiki/Chromophorehttp://en.wikipedia.org/wiki/Reactive_dyeshttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Salthttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Alkalihttp://en.wikipedia.org/wiki/Alkaline_liquorhttp://en.wikipedia.org/wiki/Vat_dyehttp://en.wikipedia.org/wiki/Potassium_dichromatehttp://en.wikipedia.org/wiki/Perspirationhttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Mordanthttp://en.wikipedia.org/wiki/Staining_(biology)http://en.wikipedia.org/wiki/PH_indicatorhttp://en.wikipedia.org/wiki/Nylonhttp://en.wikipedia.org/wiki/Leatherhttp://en.wikipedia.org/wiki/Cottonhttp://en.wikipedia.org/wiki/Sodium_sulfatehttp://en.wikipedia.org/wiki/Sodium_chloridehttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Alkalinehttp://en.wikipedia.org/wiki/Substantive_dyehttp://en.wikipedia.org/wiki/Paperhttp://en.wikipedia.org/wiki/Acetic_acidhttp://en.wikipedia.org/wiki/Acrylic_fiberhttp://en.wikipedia.org/wiki/Cationic


13/42

13

to produce the required insoluble azo dye. This technique of dyeing is unique, in that

the final color is controlled by the choice of the diazoic and coupling components. This

method of dyeing cotton is declining in importance due to the toxic nature of the

chemicals used.

Sulfur dyes are two parts "developed" dyes used to dye cotton with dark colors. Theinitial bath imparts a yellow or palechartreuse color. This is after treated with a sulfur

compound in place to produce the dark black we are familiar with in socks for instance.

Sulfur Black 1 is the largest selling dye by volume.

Food Dyes: One other class that describes the role of dyes, rather than their mode of

use, is the food dye. Because food dyes are classed as food additives, they are

manufactured to a higher standard than some industrial dyes. Food dyes can be direct,

mordant and vat dyes, and their use is strictly controlled by legislation.Many are azo

dyes, although anthraquinone and triphenylmethane compounds are used for colors

such asgreen andblue.Some naturally-occurring dyes are also used.

Table 1: Showing the pollutants associated with synthetic Dyes

S.No Dye Class Description Method of

Application

Fibers

Applied to

Typical

Fixation%

Pollutants Associate

with Dye

1. Acid Water soluble, anionic

compounds

Exhaust\Beck

\Continuous

(Carpet)

Wool, Nylon 80-93 Colour, Organic Acid

Unfixed Dyes

2. Basic Water-Soluble,

applied in weakly

acidic dyebaths;bright dyes

Exhaust\

Beck

Acrylic, Some

Polyesters

97-98 N/A

3. Direct Water soluble, anionic

compounds, can be

applied directly to

cellulosics without

mordants

Exhaust\

Beck

\Continuous

Cotton,

Rayon, Other

Cellulosics

70-95 Colour, salt, unfixed

dyes, Cationic fixing

agent, defoamers

surfactants, leveling

dispersing agents.

4. Disperse Not water soluble High

Temperature

Exhaust,

Continuous

Polyester

acetate,

other

synthetics

80-92 Colour; organic acids;

carriers; levelling

agents;phosphates

defoamers5. Reactive Water-Soluble,

Anionic Compounds,

Largest Dye class

Exhaust\

Beck\

Continuous

Cotton,

Other

Cellulosics,

60-90 Colour, Salt, Unfixed

Dye, Surfactant,

Defoamers, Diluetants

6 Sulphur Organic compounds

containing Sulphur

Continuous Cotton,

Cellulosics

60-70 Colour, Alkali, Oxidising

agents, Reducing agents,

Unfixed Dye
http://en.wikipedia.org/wiki/Sulfur_dyehttp://en.wikipedia.org/wiki/Sulfur_dyehttp://en.wikipedia.org/wiki/Chartreuse_(color)http://en.wikipedia.org/wiki/Food_coloringhttp://en.wikipedia.org/wiki/Food_additivehttp://en.wikipedia.org/wiki/Lawhttp://en.wikipedia.org/wiki/Azo_compoundhttp://en.wikipedia.org/wiki/Anthraquinonehttp://en.wikipedia.org/wiki/Triphenylmethanehttp://en.wikipedia.org/wiki/Greenhttp://en.wikipedia.org/wiki/Bluehttp://en.wikipedia.org/wiki/Bluehttp://en.wikipedia.org/wiki/Greenhttp://en.wikipedia.org/wiki/Triphenylmethanehttp://en.wikipedia.org/wiki/Anthraquinonehttp://en.wikipedia.org/wiki/Azo_compoundhttp://en.wikipedia.org/wiki/Lawhttp://en.wikipedia.org/wiki/Food_additivehttp://en.wikipedia.org/wiki/Food_coloringhttp://en.wikipedia.org/wiki/Chartreuse_(color)http://en.wikipedia.org/wiki/Sulfur_dye


14/42

14

1.3 Textile Waste Streams

1.3.1 Wastewater

Wastewater is, by far, the largest waste stream for the textile industry. Large volume wastes

include wash water from preparation and continuous dyeing, alkaline waste from preparation,and batch dye waste containing large amounts of salt, acid, or alkali. A primary source of

biological oxygen demand (BOD) includes waste chemicals or batch dumps, starch sizing agents,

knitting oils, and degradable surfactants. Wet processing operations, including preparation,

dyeing, and finishing, generate the majority of textile wastewater.

Desizing, or the process of removing size chemicals from textiles, is one of the industrys largest

sources of wastewater pollutants. In this process, large quantities of size used in weaving

processes are typically discarded. More than 90 percent of the size used by the U.S. textile

industry, or 90,000 tons, is disposed of in the effluent stream. The remaining 10 percent isrecycled (EPA, 1996). Desizing processes often contribute up to 50 percent of the BOD load in

wastewater from wet processing (Snowden-Swan, 1995). Dyeing operations generate a large

portion of the industrys total wastewater.

The primary source of wastewater in dyeing operations is spent dyebath and wash water. Such

wastewater typically contains by-products, residual dye, and auxiliary chemicals. Additional

pollutants include cleaning solvents, such as oxalic acid. Of the 700,000 tons of dyes produced

annually worldwide, about 10 to 15 percent of the dye is disposed of in effluent from dyeing

operations (Snowden-Swan, 1995). However, dyes in wastewater may be chemically bound to

fabric fibers (ATMI, 1997b). The average wastewater generation from a dyeing facility isestimated at between one and two million gallons per day. Dyeing and rinsing processes for

disperse dyeing generate about 12 to 17 gallons of wastewater per pound of product. Refer

Table#1

The effluent from the dyeing and finishing processes is characterized by strong color, high pH,

high temperature, high COD, and low biodegradability. In recent years, reactive dyes have been

most commonly used due to their advantages such as dyeing processing conditions and bright

colors. Moreover, the use of reactive dyes is rapidly growing due to the increased use of

cellulosic fibers. Generally reactive dyes contain functional groups such as azo, anthraquinone,

phthalocyanine, formazin, and oxazine as chromophore. Among the reactive dyes,

approximately 66%is unmetallized azo dye. The reactive site of the dyes reacts with functional

group on fiber under influence of heat and alkali.

One of the major factors determining the release of a dye into environment is its degree of

fixation on the fiber. Reactive dye is hydrolyzed to some extent during application processes;

some of reactive dyestuff is inactivated by a competing hydrolysis reaction. Consequently, the

release of reactive dyes into dyebath effluent is exacerbated by their relatively low fixation


15/42

15

(50e90%) to cellulosic fibers, compared with other dyes such as acid, basic, disperse and direct

dye. Reactive dyes in dyeing wastewater have been identified as recalcitrant compounds since

they contain high alkalinity, high concentration of organic materials and strong color in

comparison with other dyes. Unless coloring materials are properly removed, dye wastewater

significantly affects photosynthetic activity in aquatic life due to reduced light penetration.Refer Table 2 to know about the BOD Load associated with the textile processes.

Table 2:Table showing BOD Load associated with textile processes

Finishing processes typically generate wastewater containing natural and synthetic polymers

and a range of other potentially toxic substances (Snowden-Swan, 1995). Pollution from

peroxide bleaching normally is not a major concern. In most cases, scouring has removed

impurities in the goods, so the only by-product of the peroxide reaction is water. The major

pollution issues in the bleaching process are chemical handling, water conservation, and high

pH.

Hazardous waste generated by textile manufacturers results primarily from the use of solvents

in cleaning knit goods (ATMI, 1997b). Solvents may be used in some scouring or equipment

cleaning operations, however, more often scouring processes are aqueous-based and cleaning

materials involve mineral spirits or other chemicals (ATMI, 1997b). Spent solvents may include

tetrachloroethylene and trichloroethylene (NC DEHNR, P2 Pays, 1985). A few of the more

common textile industry water pollutants and their sources are discussed below.

In addition, Table 3 summarizes the typical pollutant releases associated with various textile

manufacturing processes.

Process Pounds of BOD per 1000

Pounds of Production

Singeing 0

Desizing

Starch 67

Starch, Mixed Size 20

PVA or CMC 0Scouring 40-50

Bleaching

Peroxide 3-4

Hypochlorite 8

Mercerizing 15


16/42

16

Table 3: Table showing the pollution load associated with Textile Industry

Process Air Emission Wastewater Residual Waste

Fiber

Preparation

Little or no air

emission

Little or no

wastewatergenerated

Fiber waste; packaging waste

and hard waste

Yarn

Spinning

Little or no air

emission

Little or no

wastewater

generated

Packaging wastes; sized yarn;

fiber waste; cleaning and

processing wastes

Slashing/

Sizing

VOCs BOD; COD;

metals; cleaning

wastes; size

Fiber/ lint; yarn waste;

packaging wastes; unused

starch-based sizes

Weaving Little or no air

emission

Little or no

wastewatergenerated

Packaging wastes; yarn and

fabric scraps; off-spec fabric;used oil

Knitting Little or no air

emission

Little or no

wastewater

generated


fabric scraps; off-spec fabric

Tufting Little or no air

emission

Little or no

wastewater

generated



Desizing VOCS from

Glycol Ethers

BOD from water-

soluble sizes;synthetic size;

lubricants; Bio-

cides; Antistatic

Compounds



Scouring VOCs from

Glycol Ether and

scouring

solvents

Disinfectant and

Insecticide

residue; NaOH;

detergents; fats;

oils; pectin; wax;knitting

lubricants; spent

solvents

Little or no Residual Waste

Generated

Bleaching Little or no air

emission

Hydrogen

Peroxide;

Sodium Silicate


Generated


17/42

17

or organic

stabilizer; high

pH

Singeing Small amount of

exhaust gasesfrom burners

Little or no

wastewatergenerated


Generated

Mercerizing Little or no air

emission

High pH; NaOH Little or no Residual Waste

Generated

Heat

setting

Volatilization of

spin finish

agents

Little or no

wastewater

generated


Generated

Dyeing VOCs Metals; salt;

surfactants;

toxics; organicprocessing

assisstants;

cationic

materials;

colour; BOD;

COD; acidity/

alkalinity


Generated

Printing Solvents, Acetic

Acid fromdrying, curing,

oven emissions,

combustion

gases and

Particulate

Matter

Suspended

Solids; Urea;Solvents; Colour;

metals; heat;

BOD; foam


Generated

Finishing VOCs,

Contaminants in

purchasedchemicals, gases

Particulate

Matter

BOD; COD;

Suspended

Solids; toxics;Spent Solvents


Generated


18/42

18

1.3.2 Metal Toxicity

Many textile mills have few or no metals in their effluent, but whenever metals are present,

they may include metals such as copper, cadmium, chromium, nickel, and zinc. Sources of

metals found in textile mill effluents may include fiber, incoming water, dyes, plumbing, and

chemical impurities. Dyes may contain metals such as zinc, nickel, chromium, and cobalt (ATMI,

1997b). In some dyes, these metals are functional (i.e., they form an integral part of the dye

molecule); however, in most dyes, metals are simply impurities generated during dye

manufacture. For example, mercury or other metals may be used as catalysts in the

manufacture of certain dyes and may be present as byproducts. Metals may be difficult to

remove from wastewater (EPA, 1996).

1.3.3 Aquatic Toxicity

The aquatic toxicity of textile industry wastewater varies considerably among production

facilities. Data are available that show that the wastewater of some facilities has fairly high

aquatic toxicity, while others show little or no toxicity. The sources of aquatic toxicity can

include salt, surfactants, ionic metals and their complexed metals therein, toxic organic

chemicals, biocides, and toxic anions (EPA, 1996; ATMI, 1997b). Most textile dyes have low

aquatic toxicity. On the other hand, surfactants and related compounds, such as detergents,

emulsifiers, dispersants, are used in almost every textile process and can be an important

contributor to effluent aquatic toxicity, BOD, and foaming (EPA, 1996).

1.3.4 Air Emissions

Although the textile industry is a relatively minor source of air pollutants compared with many

other industries, the industry emits a wide variety of air pollutants, making sampling, analysis,

treatment, and prevention more complex. Textile operations involve numerous sources of air

emissions. Operations that represent the greatest concern are coating, finishing, and dyeing

operations. Textile mills usually generate nitrogen and sulphur oxides from boilers and areoften classified as major sources under the Clean Air Act (EPA, 1996). Other significant

sources of air emissions in textile operations include resin finishing and drying operations,

printing, dyeing, fabric preparation, and wastewater treatment plants (ATMI, 1997b).

Hydrocarbons are emitted from drying ovens and, in particular, from mineral oil from high-

temperature (200C) drying and curing.


19/42

19

Carriers and solvents may be emitted during dyeing operations depending on the types of

dyeing processes used and from wastewater treatment plant operations. Other potential

pollutants can include solvent vapors containing toxic compounds such as acetaldehyde,

chlorofluorocarbons, pdichlorobenzene, ethyl acetate, and others. Some process chemicals,

such as methyl naphthalene or chlorotoluene, may exhaust into the fibers and are later emittedfrom dryers as VOCs (EPA, 1996).

Textile manufacturing can produce oil and acid fumes, plasticizers, and other volatile chemicals.

Acetic acid emissions may arise from storage tanks, especially from vents during filling.

Carbonizing processes, used in wool yarn manufacture, may emit sulfuric acid fumes and

decating, a finishing process applied to wool fabrics to set the nap and develop luster, produces

formic acid fumes. In addition, cleaning and scouring chemicals were estimated at 10,500

metric tons in 1988 (EPA, 1996).

1.3.5 Other Wastes

The primary residual wastes generated from the textile industry are non-hazardous. These

include fabric and yarn scrap, off-spec yarn and fabric, and packaging waste. Cutting room

waste generates a high volume of fabric scrap that can be reduced by increasing fabric

utilization efficiency in cutting and sewing. Typical efficiency for using fabric averages from 72

to 94 percent. As a result, fabrication waste from carpets amounts to about 2 percent of an

annual 900 million square yards of production (a value of $100 million). Denim cutting waste

accounts for approximately 16 percent of denim production, or 100 million pounds annually.

Although, a large portion of cutting waste goes to landfill, some innovative programs beingimplemented to recycle this material. Some facilities collect cotton lint for resale. Cotton trash,

leaves, and stems collected during the yarn formation have been sold to farmers as animal

feed.


20/42

20

2. Existing Nalco Program for Colour Removal

At present, Nalco has a specialized chemical N-8123 which is a polymer based on

cyanoguanidine and formaldehyde. The chemical is very effective in removing colour. Besides,

being an organic polymer it is bio-degradable and does not pose serious environmental

hazards. Another added advantage is that the volume of sludge produced is much less. It,

therefore, reduces the overall expenditure in sludge handling processes-dewatering,

transportation and disposal. The problem concerning the current program is that the required

dosage is very high for good colour removal. As high as 400-500 ppm of the coagulant is

required to achieve effective colour removal. The industry prefers to purchase inorganic

coagulants like alum, ferric chloride, ferrous sulphate etc. which are inexpensive and easily

available. In order to cater to the real-world scenario Nalco looks forward to achieving aneconomical and sustainable program for colour removal.


21/42

21

3. Objective and Scope of the Project

Indian Textile sector has grown by more than 5% in the last two fiscal years and is projected to

grow at ~16% by 2012. This necessitates the need for proper infrastructure development to

achieve the projected growth. One of the biggest challenges which already exists and is going to

pose a challenge is the development of cost effective and sustainable treatment programs for

the wastewater that comes out of textile processing (Desizing, Scouring, Bleaching, Mercerizing,

Dyeing, and Washing). Over the last couple of years, Nalco has invested a tremendous amount

of effort to develop new value added programs for textile wastewater treatment. The results of

the studies have been very encouraging and are currently practiced in Nalco. However the

market is in demand of more efficient and economical programs. This research work conducted

at Nalco involved the study of the following:

1. Understand briefly about the different textile processes

2. Understand the contaminants and their concentration ranges in the textile wastewater

3. Perform background study on the existing treatment programs for the textile wastewater

4. Research for new possible treatment processes which could be efficient in treating the textile

wastewater which could involve mechanical and/or chemical programs.

5. Evaluate the performance of these encouraging programs by running laboratory tests and

comparing against the commonly used existing programs. Recent research has shown some

promise on blended chemical programs which were tested by conducting experiments along

with the new programs proposed from the research.


22/42

22

4. Experimental Section

4.1 Testing Procedure

4.1.1 Jar Testing Method

Jar Tests were conducted to determine the optimum dosage of various chemicals added tocarry out colour-removal using the process of Sedimentation Aided with Coagulation and

Flocculation. One Jar was tested at a time using the following procedure.

1. First a 25O mL dye water solution was placed in a beaker.2. The Jar was made to rotate at a speed of 250 R.P.M for duration of two minutes. This is

known as the rapid mix.

3. To it freshly prepared Lime solution was added to raise the pH to the desired level.4. Within few seconds of addition of Lime, freshly prepared solution of coagulant was

added.

5. In the last thirty seconds of the rapid mix, flocculants was added to the beaker.6. The Jar Tests is programmed to rotate at a speed of 75 R.P.M for one minute once the

rapid mix is over. This is termed as slow mix.

7. On Completion of slow mix, the blades are removed and the flocs formed are made tosettle down for five minutes.

4.1.2 Measurement of True Colour

1. On DR 2800 Spectrophotometer Press STORED PROGRAMS and press on the optionSelect By Number.

2. Select the number 120 for the measurement of True Colour.3. Add 10 mL of Milli-Q water in the cuvette. Place it in the cuvette holder, close the lightshield and press zero.

4. Once the display shows zero, recheck the value by pressing Read.5. The water sample must be filtered through a 0.45 micro-meter syringe filter.6. Place the filtered water sample in the cuvette and read the colour value in Pt.-Co units.

4.1.3 Turbidity Measurement

1. Turbidity is measured using HACH 2100 Qis Turbidimeter.2. The instrument is first calibrated using standard solutions of known concentration

prepared from formazin.

3. After calibration, the sample is placed is placed in cuvette and tightly capped.4. It must be properly wiped out from the outer surface.5. Shake vigorously and place the solution in turbidimeter.6. Press READand note down the reading of Turbidity.


23/42

23

4.1.4 COD Measurement

1. Homogenize 100 mL of sample for 30 seconds in a blender. For samples containing largeamounts of solids, increase the homogenization time. If the sample does not contain

suspended solids, omit steps 1 and 2.

2. For the 20015,000 mg/L range or to improve accuracy and reproducibility of the otherranges, pour the homogenized sample into a 250-mL beaker and gently stir with a

magnetic stir plate.

3. Turn on the DRB200 Reactor. Preheat to 150 C.4. Remove the caps from two COD Digestion Reagent Vials. (Be sure to use vials for the

appropriate range.)

5. Hold one vial at a 45-degree angle. Use a clean volumetric pipet to add 2.00 mL ofsample to the vial.

6. Hold a second vial at a 45-degree angle. Use a clean volumetric pipet to add 2.00 mL ofdeionized water to the vial.

7. Use a Pipet to add 0.20 mL for the 20015,000 mg/L range.Cap the vials tightly. Rinsethem with water and wipe with a clean paper towel.

8. Hold the vials by the cap over a sink. Invert gently several times to mix. Insert the vials inthe preheated DRB200 Reactor. Close the protective lid.

9. The sample vials will become very hot during mixing. Heat the vials for two hours.10.Turn the reactor off. Wait about 20 minutes for the vials to cool to 120 C or less.11.Invert each vial several times while still warm. Place the vials into a rack and cool to

room temperature.

12.Select the ultra-low range (DR 2800 only), low range, or high range test. Install the LightShield in Cell Compartment #2.

13.Clean the outside of the vials with a damp towel followed by a dry one.14.Insert the blank into the 16-mm cell holder. Press ZERO. The display will show: 0.0 mg/L

COD.

15.Insert the sample vial into the 16-mm cell holder.16.Press READ. Results are in mg/L COD.17.If using High Range plus COD Digestion Reagent Vials, multiply the result by 10. For most

accurate results with samples near 1500 or 15,000 mg/L COD, repeat the analysis with a

diluted sample.

4.2Polymer Make-up Procedure

An anionic flocculant-9901 was prepared in 100 mL glass reactor using a mechanical stirrer. The

solid crystals were thoroughly weighed and the final volume was made upto 100 mL. The

aqueous solution was stirred for 30 minutes at 60-70 R.P.M.


24/42

24

4.3Coagulant Make-Up Procedure

The Coagulant dose was calculated and weighed using a weighing balance. The weighed

chemical was transferred to a volumetric flask and final volume was adjusted to 100 mL.

4.4 pH Measurement

pH is measured using an instrument called Myron L Company Ultrameter II. Each time before

use it must be caliberated using pH standards of known pH. Three standards exist having pH 4,

7 and 10. The electrode must be properly rinsed in the solution.

TDS Measurement

Determination of TDS is done using Myron L Company Ultrameter II. Each time before use the

instrument must be caliberated using a solution of known conductivity-0.1 N KCl having a

conductivity of 12.88 S/cm. After calibration the electrode is thoroughly rinsed with the

solution and the TDS is measured.


25/42

25

5. Results and Discussion

5.1 Variation of Dye Concentration with Optimum Coagulant Dose.

Synthetic dye wastewater was prepared using Cotton Blue Dye. The Concentration of the dye

used was varied from 15ppm, 50 ppm and 100 ppm. Jar Tests were conducted to determine the

optimum coagulant Dose. N-8123 was used as the coagulant and the flocculant used was N-

9901. Refer# Figure 1.

Figure 1: Graph showing variation of Coagulant Dose with Dye Concentration

The result showed a linear variation of dye concentration with the optimum Coagulant Dose.

With increase in dye concentration the dosage of coagulant dose needed for efficient colour

removal was increased; Figure 1.

5.2 Dosage Optimization of N-8123 on 100 ppm Cotton Blue Dye.

Synthetic wastewater was prepared using 100 ppm Cotton Blue Dye. The dose of N-8123 was

varied from 0 to 400 ppm and parameters such as pH, Turbidity, Colour and COD were

150

300

400

0

100

200

300

400

500

0 20 40 60 80 100 1208123Dose(ppm)

Dye Concentration (ppm)

Optimum N-8123 Dose (ppm)


26/42

26

determined. The optimum dose of lime and N-9901 was determined by conducting a series of

bottle tests. The data obtained is shown in Table 4.

Table 4: Table showing optimum dose of N-8123 for 100ppm Dye

8123

(ppm)pH Turbidity(NTU) TDS (ppm)

Colour

(Pt.-

Co.)

COD

(ppm)

0 8.06 2.88 98.97 536 115

300 11.56 58.1 297 154 76

325 11.4 4.2 342 32 64

350 11.26 3.17 361 25 37

375 11.29 3.01 382 17 18400 11.27 2.97 400 12 16

In Table 4; 400ppm of N-8123 is required to lower down the colour value from 536 Pt.-Co units

to 12 Pt.-Co units. The dose is quite high which makes it a very expensive option to be

implemented.

536

154

32 25 17 12

0

75

150

225

300

375

450525

600

0 300 325 350 375 400

TrueColour(Pt.-Co

)

N-8123 Dose (ppm)

Colour (Pt-Co)

Figure 2:Graph showing Optimum Dose of N-8123 v/s True Colour


27/42

27

Picture 1: Photograph showing raw and treated dye solution using N-8123

5.3 Dosage Optimization of 133L Dose on 100 ppm Cotton Blue Dye Solution.

133L is an inorganic coagulant which is easily available in the market at low cost. While

conducting Optimization Studies on 133L, it was observed that 133L worked at lower pH in

comparison to N-8123. Lime dose was kept at 100 ppm and 3 ppm of flocculant was added.

However, the colour removal performance of 133L was weaker as can be seen from the plot

83

77

9294

75

80

85

90

95

100

200 250 300 350 400

Colour(Pt.-Co)

133L Dose (ppm)

133L DOSE

(ppm)

Figure 3:Plot showing Optimum 133L Dose for 100ppm Cotton Blue Dye


28/42

28

below. 133L could lower down the colour value to not less than 77 Pt.-Co. units; Refer Figure 2

and Figure 3.

It can be inferred from the plot that the optimum dose of 133L is 250 ppm, Refer Figure 5. For

Coagulant Dose lower than 200 ppm the solution was highly turbid and the colour removalperformance was bad. One can also see that for dosage over 300 ppm the colour of the effluent

is nearly constant. The table shown below shows the dosage of chemicals and effluent

parameters-TDS, pH, Turbidity.

Table 5: Table showing data collected on optimization of 133L Dose.

LIME

DOSE

(ppm)

133L DOSE

(ppm)

9901

DOSE

(ppm)

COLOUR

(Pt.-Co.)

TURBIDITY

(NTU)

TDS

(ppm)

pH

0 0 0 532 2.56 100 8.04100 100 3 HIGHLY TURBID

100 150 3 HIGHLY TURBID

100 200 3 83 4.73 300 9.96

100 250 3 77 1.14 200 8.68

100 300 3 92 0.94 300 8.93

100 350 3 94 1.16 400 9.84

The table shown above shows that the pH of the optimum system is 8.68 along with having TDS

and Turbidity values as 200 ppm and 1.14 NTU respectively.

5.4 Dosage Optimization of N-8123 and 133L Blend.

In order to enhance the colour removal efficiency of N-8123 at lower dosage it was blended

with 133L. The data obtained is shown. Table 6:Table showing data obtained by blending N-

8123 with 133L

Lime

(ppm)

N-8123

(ppm)

133L

(ppm)

N-9901

(ppm)

Colour

(Pt- Co)

Turbidity

(NTU)

TDS

(ppm)pH

COD

(ppm)

0 0 0 0 525 2.64 100 8.21 144

100 100 250 3 58 2.79 300 9.42 47

100 150 250 3 59 3.26 300 9.5 36

100 200 250 3 61 2.94 300 9.42 35

100 250 250 3 22 3.16 300 9.36 37


29/42

29

In Table 6, it can be seen that the dosage of 133L is kept at 250 ppm. This is a result of another

experiment wherein optimum dose of 133L was determined. The plot showing the variation of

133L Dose with Colour unit of the treated effluent is shown below:

It can be seen from the above plot that initially when the 133L dose is varied as 250ppm,

300ppm and 350ppm the colour value of the treated effluent is 59 Pt.-Co, 59 Pt.-Co and 58 Pt.-

Co respectively. As a result of which the most economical dose is chosen which 250ppm is.

When the dose is increased to 400 ppm the colour value drops down to 38 Pt.-Co. The reason

for choosing 250 ppm over 400 ppm is that it will increase the cost of handling, operation and

maintenance of the plant. Moreover, 133L is used in combination with N-8123, thereforeapplication of such high dosage of a single coagulant will not be economical.

It can be inferred from Figure 5,that a blend of N-8123 with 133L lowered down the colour

value from an initial value of 525 Pt.-Co to a final value of 58 Pt.-Co utilizing 100 ppm Lime, 100

ppm N-8123, 250 ppm 133L and 3 ppm Anionic-9901. This is a remarkable improvement as 250

ppm of 133L alone could not lower down colour value beyond 77 Pt.-Co (Refer Figure 4). The

experiment conducted using N-8123 alone utilized 400 ppm of the chemical to lower down the

colour value to 12 Pt.-Co units (Refer Figure 3). In order to compensate the high cost the idea of

blend is considered feasible with respect to industry. The study of pH variation on the blend

was also conducted; Refer Figure 5.

Figure 4: Plot showing the optimum 133L Dose for blending with N-8123


30/42

30

The pH was varied from 8.5 to 12 by varying the dose of Lime added. The minimum value of

colour was obtained at 100 ppm of lime at a pH of 9.42 and was thus considered optimum. By

varying the pH the final colour value lay in the range of 60 Pt.-Co to 85 Pt.-Co. No drastic

changes were observed. This observation is highly useful with respect to a real world situation

as it eliminates the constant monitoring of pH at all intervals. This will lower down the need for

chemicals and plant personnel to maintain a certain pH. Below we can see the photograph the

raw and treated effluent when N-8123 is used for colour removal.

5.5 Optimization of FeCl3 Dose on 100 ppm Cotton Blue Dye

Ferric Chloride is known to have good floc forming potential. Iron (Fe) undergoes a change in

oxidation state from +3 to +2 i.e. ferric ion changes to ferrous ion and precipitates out. Since, it

is inexpensive and easily available; it is widely used in Industry for carrying out coagulation and

Flocculation. A lab study was conducted in order to optimize the dose of ferric chloride. The

results are tabulated in Table 6.

Figure 5: Plot showing pH variation of the 133L and N-8123 Blend


31/42

31

Table 7: Table showing Optimized FeCl3 Dose

Lime

Dose(ppm)

FeCl3

Dose

(ppm)

9901

Dose

(ppm)

Colour

(Pt-

Co)

Turbidity

(NTU)

TDS

(ppm)pH

0 0 0 528 2.04 100 8.01

200 100 3 55 4.98 1100 11.39

200 150 3 55 2.55 700 11.20

200 200 3 55 3.50 700 11.30

200 250 3 82 1.94 600 10.98

200 300 3 76 2.01 600 10.73

Using the table above, one can conclude that a dose of 100 ppm, 150 ppm and 200 ppm lead to

a final colour value of 55 Pt.-Co units. An increase in dosage beyond that showed noimprovement. The plot of Ferric Chloride (FeCl3) v/s Colour value of the treated effluent is as

follows:

The colour removal performance of Ferric Chloride (FeCl3) was found to be better than 133L.

The optimum dose was found to be 100 ppm of Ferric Chloride.

Figure 6: Plot showing optimum Ferric Chloride Dose


32/42

32

5.6 Optimization of a blend of Ferric Chloride (FeCl3) and N-8123 on 100 ppm

Cotton Blue Dye.

The results from the previous experiment (Refer to Figure 6) show that Ferric Chloride has a

high colour removal potential. In order to exploit its potential it was blended with N-8123 in

order to determine the best possible combination to carry out colour removal economically.Refer Table 8 for the data obtained in the experiment conducted above.

Table 8: Table showing optimum Ferric Chloride Dose for Blending with N-8123

Initially the dose of N-8123 was kept constant at 100 ppm and the optimum FeCl3 was

determined. The Lime Dose was kept constant to 200 ppm and the dose of the flocculant was

constant at 3 ppm. Using Table 8, one can conclude that 300 ppm of Ferric Chloride gave

appreciably good results. Later the dose of FeCl3 was kept constant and the optimum

concentration of N-8123 was determined. At 250 ppm of Lime, 300 ppm of FeCl 3and 3 ppm of

Anionic 9901, the optimum dose plot came as follows:

FeCl3 (ppm)Colour

(Pt- Co)

Turbidity

(NTU)

TDS

(ppm)pH

0 525 3.07 100 8.14

100 115 3.86 1000 11.79

150 113 1.87 1000 11.74

200 100 3.34 900 11.62

250 95 1.13 800 11.54

275 91 1.66 1000 11.63

300 72 1.28 800 11.43

400 85 1.21 900 11.56

450 92 2.56 800 11.47


33/42

33

The graph shows that the optimum dose of N-8123 in combination with FeCl3 is 300 ppm. The

final combination is as: 250 ppm Lime, 300 ppm FeCl3, 100 ppm N-8123 and 3 ppm Anionic

9901. In this case; the amount of chemicals used is much more than the previously used

combination. The amount of chemicals used in the blend of 133L and N-8123 is: 100 ppm Lime,

100 ppm N-8123, 250 ppm 133L and 3 ppm Anionic 9901.

5.7 Industrial Wastewater Testing

5.7.1 Industrial Sample 1

Sample Description: Sample received from Huntsman Ltd. at Baroda, Gujarat.

Background

Huntsman Ltd. at Baroda is a textile manufacturing company. The effluent treatment plant is

composed of both primary clarifier followed by a secondary one. The clarified water from

secondary clarifier contains high level of color (~1000 Pt.-Co.). Currently, they are usingactivated carbon for the final color removal after secondary treatment. The clarified water is

being discharged to the environment. The activated carbon process the very cost intensive.

They wish to have a suitable program for the final color removal after secondary treatment.

The current parameters are as follows:

Figure 7: Plot showing optimum Dose of N-8123 for blending with Ferric Chloride


34/42

34

Required Testing:

Evaluation of suitable chemical program for the final color removal (


35/42

35

.

From the above graph one can conclude that 300ppm of FeSO4 gave a colour value less than

100 Pt.-Co units. Later the experiment was carried using N-8123 alone, in order to study the

performance of N-8123 alone. The dose of 8123 was varied and the following plot was

obtained:

Shown Below is a photograph of the Raw Samples and The treated Sample.

Figure 8: Plot showing Colour Removal of Huntsman Ltd Sample

Figure 9: Plot showing Colour Removal Performance of N-8123 alone.


36/42

36

Picture 2: Photograph of Huntsman Ltd. Sample

Recommended Program

Option #1: 800 ppm Lime+ 200 ppm N-8123 + 300 ppm FeSO4+ 4 ppm N-9901

Option#2: 800 ppm Lime+ 200 ppm N-8123 + 200 ppm FeSO4+ 4 ppm N-9901

Industrial Sample 2

5.7.2. Industrial Sample 2Sample Location:Merchem Limited, Gujarat

Background

Merchem Ltd. is a rubber specialty chemical manufacturing company. The effluent water is a

mixture of mother liquor and washings from the process. The COD of the effluent is

~10,000ppm and there is a need for suitable COD removal program. The present ETP schematic

is shown below. Presently they are sending the partially treated effluent (COD


37/42

37

List of Critical Topics

Sludge carryover needs to be minimized. Stage wise COD reduction including the biological treatment needs to be improved.

Alternative advanced oxidation process (AOP) to improve the biodegradability andreduce toxicity should be considered.

Possibility of introducing continuous mode of operations needs to be explored(Presently neutralization/Fenton is being done in batch mode).

Improved clarification system after coagulation stage. Alternative adsorption media other than carbon. Possibility of water reuses and recycles.

Results Obtained

The lab study conducted on Merchem Ltd, Gujarat Sample gave the following results:

Table 9: Table showing data received by conducting Lab Study on Merchem Ltd Sample

Lime

Dose

(ppm)

ZnCl2

Dose

(ppm)

8123

Dose

(ppm)

9901

Dose

(ppm)

Colour

(Pt.-Co)

Turbidity

(NTU)

TDS

(ppm)pH

1500 2000 500 8 124 6.15 49370 10.33

1500 2500 500 8 102 6.4 50190 9.641500 3000 500 8 83 10.03 51450 9.15

1500 2500 1000 8 81 6.67 50610 9.56

1500 2500 1500 8 88 8.44 50430 9.31

1500 2500 0 8 124 6.68 50620 9.39

1500 0 1500 8 HIGHLY TURBID

One can make the following conclusions:

Very high dosage of Lime is required (~1500ppm) to maintain the optimum pH forcolour removal.

N-8123 alone could not lower down the colour value to less than 124 Pt.-Co units. ZnCl2 when applied alone produced an effluent having high colour and turbidity. The optimum combination is found to be 1500ppm Lime+2500ppm ZnCl2+1000ppm N-

8123+8ppm of Anionic 9901.


38/42

38

The plot of percentage colour removal v/s the dosage of two coagulants used-ZnCl 2 and a

photograph of the treated effluent is shown below:

Picture 3: Photograph of Merchem Ltd. Sample after Treatment

The colour value of the Merchem Ltd. Sample came down from 492 Pt.-Co. units to 81 Pt.-Co

units.

Treated Effluent Using Optimized

Program-1500ppm Lime+2500

ZnCl2+1000ppm N-8123+ 8ppm

N-9901

Sludge

Colour Value of

Treated Effluent=81

Figure 10: Plot showing % age Colour Removal


39/42

39

6.Conclusion

The study conducted on Synthetic wastewater revealed that as the dye concentration is

increased the amount of coagulant dose required increases linearly. The optimum dose of N-

8123 required for effective decolourization of 100 ppm Dye solution is 400ppm. Later,

optimization studies were carried on inorganic coagulants such as 133L and Ferric Chloride. The

results so obtained revealed that 250ppm of 133L could lower down the colour value to 59 Pt.-

Co units from an initial value of 525 Pt.-Co units. In order to enhance its colour removal

efficiency it was blended with N-8123 and the optimized program was100 ppm Lime, 100 ppm

N-8123, 250 ppm 133L and 3 ppm Anionic 9901. The colour of the treated effluent was 58,

which is no improvement than 133L alone but the amount of chemicals in terms of Lime, 133Land N-8123 is much less. Also the turbidity of the effluent is improved. Another inorganic

coagulant was blended with Nalco chemical in order to draw a comparison with the blending of

133L with N-8123.

It was found that Ferric Chloride alone utilized 200ppm of Lime, 100 ppm of Ferric Chloride and

3 ppm of Anionic-9901 to lower down the colour value from 528 Pt.-Co units to 55 Pt.-Co units.

When Ferric Chloride was blended with N-8123 it was seen that 250 ppm Lime, 300 ppm FeCl3,

250 ppm N-8123 and 3 ppm Anionic 9901 could lower down the colour value to 31 Pt.-Co units.

pH variation Studies of both the optimized blends were also carried out and it was inferred that

the pH of both the systems lied in the range of 8.5 to 10.5. Change in pH did not result in drasticresults. This inference is favourable with respect to industry since sudden fluctuation in pH will

not affect the colour removal performance of the system to a great extent.

The laboratory studies were extended to the Industrial Wastewater Sample. Two Samples were

Tested from Huntsman Ltd, Baroda and Secondly from Merchem Ltd, Gujarat. The Huntsman

Ltd. Sample had an initial colour value of 1000 Pt.-Co units. It was tested for the blend of 133L

and N-8123. It showed good results at very high dosage of 133L and 200 ppm of N-8123. It

could remove colour upto a maximum limit of 126 Pt.-Co units. It was not accepted since the

target colour of the effluent was less than 100 Pt.-Co units. Later, the combination of Ferric

Chloride with N-8123 was tested. It could not bring down the colour value to lower than 230Pt.-Co units. Thereafter, Ferrous Sulphate in combination with N-8123 was tested on the textile

wastewater sample. It showed very good performance and the optimized combination was:

800ppm of Lime, 200ppm of N-8123, 300ppm of Ferrous Sulphate and 8ppm of Anionic 9901.

The combination could bring down the colour value to 76 Pt.-Co units. The Second Sample

tested was from Merchem Ltd, Gujarat. The optimized combination of N-8123 and 133L, N-

8123 and Ferric Chloride and N-8123 and Ferrous Sulphate failed to remove colour upto a great


40/42

40

extent. Therefore, a new combination of Nalco chemical based on Zinc Chloride was combined

with N-8123 to bring down the colour value to 81 Pt.-Co units. The optimized combination was

1500ppm of Lime, 2500ppm of Zinc Chloride based Nalco Product, 1000ppm of N-8123 and

8ppm of 9901. Thus, one can infer that water coming from different sources has different

chemistries and based on the specific water chemistry the chemicals can be blended to carryout effective colour removal.


41/42

41

7.Future Directions

The overall aim of the project was to discover a new chemistry in the field of colour

removal. The study conducted so far has employed the use of blends utilizing Nalco

Chemicals and easily available Commercial chemicals to carry out colour-removal.

The idea is to carry out wastewater treatment following a holistic approach. Colour

Removal is not targeted at the expense of other impurities. Decolourization should

be carried out alongwith overall wastewater treatment.

In order to come up with a product that is cost-effective and sustainable, there is a

need to study the water chemistry of wastewater coming from different sources. It

is important to study the basic reaction mechanism responsible for colour removal.Based on the study of reaction mechanism, a new chemical can be developed that is

environmental friendly and causes effective treatment at low dosage.

The new chemical may follow an entire new mechanism based on the blends of

Nalco Chemicals with inorganic chemicals. This can be postulated after thorough

research work in this field.


42/42

8.References

1. Karcher SA, Screening of commercial sorbents for the removal of reactive dyes. Dyes

Pigments 2001;51:111e25.

2.Choi JH, Shin WS, Lee SH, Joo DJ, Lee JD, Choi SJ, et al. Applications of synthetic polyamine

flocculants for dye wastewater treatment. Sep Sci Technol 2001;36(13):2945e58.

3.Papic S, Koprivanac N, Bo_zic AL. Removal of reactive dyes from wastewater using Fe(III)

coagulants. J Soc Dyers Colour 2000;116(11):352e8.

4.Lee SH, Shin MC, Choi SJ, Shin JH, Park LS. Improvement of flocculation efficiency of water

treatment by using polymer flocculants. Environ Technol 1998;19(4):431e6.

5. Profile of the Textile Industry, document number: EPA/310-R-97-009

6.Joo, et al., Decolorization of reactive dyes using inorganic coagulants and synthetic polymer,

Dyes and Pigments, 2007, 73, 59-64.

7. Collins et al. United States Patent, vinylamine polymers and coagulants for removing colour

from paper mill effluents, Patent Number 5,435,921

8. Selcuk, H., (2005). Decolonization and detoxification of textile waste water by ozonation and

coagulation processes. J. Dye. Pig., 64, 217-222.

9. Kang, S., (2000). Decolonization of textile waste water by photo-fenton oxidation technology.

J. Chemosphere, 41, 1287-1294.

Report Ishita Kumar

Documents

Transcript of Report Ishita Kumar