People around the world share one fashion love “blue jeans.” Denim may be stylish, but also has many unexpected downsides pollutants.Two techniques commonly used that became the hallmarks of blue jeans are the well known indigo color and the worn out look that make the statement in a pair of jeans. Unfortunately, the chemicals involved in their processes contribute to pollution. Today the indigo dye is produced from coal or oil (a process that can release toxic byproducts like cyanide and formaldehyde) while stonewash uses volcanic rocks or pumice stones which releases pumice dust that endanger worker’s health and produces gritty sediment waste.
http://cnn.com/video/?/video/world/2010/04/26/chang.blue.jeans.cnn
Showing posts with label Environment. Show all posts
Showing posts with label Environment. Show all posts
Friday, May 27, 2011
Friday, April 9, 2010
Polyester Microfibers:- Dyeing and Wet Processing
Microfiber
Due to their fineness, the total surface area of microfibre yarn or fabric is far greater than ordinary fibres. Threfore
5.Larger external surface means an increase in number of threads exposed to light which, on destruction of dye, is expressed as lower light fastness rating.
6. Wash fastness and color fastness to rubbing is also poor.
7.Staple microfibres offer difficulty in carding.
The problems in wet processing of microfibers can be overcome by
1.Better knowledge about the size applied and optimum parameters during desizing operation.
To achieve satisfactory dyeing effects ,desizing and refining process must be done before dyeing and after desizing and refining , there should be no impurities left such as electrolyte, antistatic finishing agent , spin finishes and blot.
2.Pre-setting
Suitable pre setting conditions ( time ,temperature and tension) helps not only in stable dimensional stability ,softness but also better dyeing results.
3.Alkali weight reduction
Alkali weight reduction s to treat the fabric with concentrated alkali at high temperature.fber molecule hydrolyse under this condition and lose some weight with change in properties, thus space occurs between crossing points and rubbing resistance relative to slippage among yarns becomes small.Alkali weight reduction makes fabric soft, liveliness, limber and improved absorption.
2.Careful selection of the dyes.
Proper dye selection which are
1.Compatible
2.Having same exhaustion rates
3.Having high wash fastness properties.
4.Good migration and levelling properties
eliminates problems regarding build-up and fastness properties.
Disperse dyes for polyester microfibers
3.Optimizing the dyebath conditions and dyeing cycle.
Optimised dyeing cycles can be worked out by controlling the temperature to account for the high rate of dyeing and to eliminate the risk of uneven dyeing.Chemicals and dyes to be added at, at least 10-20 deg.C lower temperature than normal polyester fiber dyeing. The additions of dyes must be progressive or devided at least into 4 parts. The heating rate must be slow from 40 deg C to 100 deg C. 10-20 min more holding time required at 130 deg C as compared to normal PES.
4.Proper selection of Dyeing machinery.
The dyeing machine must have the required automation to fufil the requirements of microfiber dyeing such as microprocessor controlled dosing , proper and accurate heating rate control etc.
5.Proper selection of dyebath additives
such as
Levelling agents :- A strong levelling agent which shall start working at lower temperatures.
Dispersing agents :- Higher quantities of dispersing agents are needed because amount of dyes required are more to produce the desired depth.
Chelating agents:-
Anticreasing agents,Dyebath softners/Lubricants :- Because microfiber textiles are prone to creasing , therefore use off dyebath lubricants is must.
6.Proper aftertreatment of dyed goods.
Soaping :- In order to obtain satisfactory color effect , fabric should be soaped after dyeing .Soaping is the key process to achieve satisfactory dyeing results on polyester especially polyester / nylon microdenier fabric.
Reduction clear :-Good reduction clear process is needed to achieve satisfactory washing , rubbing and light fastness properties.
Washing :-Is required for neutralising and removing alkali after reduction clear treatment.
Softening, anti soil and antistatic treatment :-Because microdenier fiber easily stains and produces static charges, a hydrophilic ,antistatic and antisoil treatment besides softening is highly recommended to ensure fabric softness and comfortability.
http://www.tex.in/education/nextiles/fib/mic/mic.html
http://ygmfranchise.blogspot.com/2007/07/cleaning-tips-microfiber.html
http://www.microfibergreen.com/is-microfiber-green-product.html
http://www.norwexnow.com/microfiber%20science.html
A synthetic fiber that is extremely soft, lightweight, breathable, durable and ultrafine. In fact, microfibers are two times finer than silk and one hundred times finer than a human hair. Microfiber is currently manufactured from acrylic, nylon, polyester and rayon.Ultra-microfibers on the market are even finer – some having thickness of just 1/200th the thickness of human hair!
Microfibres refer to staple fibres, or individual filaments within yarns, which have fineness less than 1 decitex ( 1 grams per 10,000 meters) and For any fiber to be classified as microfibre yarn, the weight per 10,000 metres of yarn (dtex) is divided by the number of filaments (f), the result must be below 1.
All about microfibers
All about microfibers
Properties of Polyester Microfibers
- Lightweight and flexible
Good stability and shape retention
Anti-wrinkle property
Have a wicking ability that permits perspiration
Comfortable to wear as they are more spongy
Doesn't water stain - superior water repellency is available
Woven or knitted into a very high quality fabric construction
Formerly commenced as a polyester microfiber, today you can find nylon, rayon and acrylic microfibers too.
Strong and durable, water repellent and wind resistant -so tightly woven, that the fabric can't be penetrated by wind, rain or cold
Lightweight, resilient or resist wrinkling, have a comfortable array, preserve shape and resist pilling
The positively charged microfibers draw dust; the tiny fibers are capable to enter the microscopic surface voids most materials
Washable, dries quickly and also washable in at the water temperatures up to 200 degrees and their characteristics will remain intact.
Electrostatic effect - Hair, lint and other dust particles are attracted and grabbed by the microfibers without lifting dust.
The density of the material allowable it to grip six to eight times its weight in water hence high absorbing power capacity
The attraction capability of the microfibers is so sound, even absorbs bacteria and germs - hence can be use as germ or bacteria free purpose
The fabric consists of millions of small tiny conduits that carry oil and grease too.
Benefits of microfibers
Comfortable - very soft, texture like silk, lightweight
Due to its fineness and superior fiber surface area making deep, rich and bright colors achievable
Less "sweaty" in warm weather than usual synthetics
Quickly cleanable - clean just with water
Highly intense and shrink-resistant
Presents insulation and breathability
Change without help - to establish lovely drape
Very fine - finer than the most precise silk
More reusable for cleaning alternative - compared to other mops more efficient and long life
Due to their fineness, the total surface area of microfibre yarn or fabric is far greater than ordinary fibres. Threfore
1.Due to its special structure ,micro fibers has much larger quantity of size ,oil agents and wax on warp yarns.
2.Since microfibres have very small interstitces, with consequent difficulties of size accessibility and duffusibility, desizing becomes quite difficult and costly.
3.Microfibres have greater absorption area resulting in a dyeing rate four times higher than that of normal, which can cause unlevelness in dyeing.
4.They also require more dyestuff than standard fibres to obtain the same depth of shade. 5.Larger external surface means an increase in number of threads exposed to light which, on destruction of dye, is expressed as lower light fastness rating.
6. Wash fastness and color fastness to rubbing is also poor.
7.Staple microfibres offer difficulty in carding.
The problems in wet processing of microfibers can be overcome by
1.Better knowledge about the size applied and optimum parameters during desizing operation.
To achieve satisfactory dyeing effects ,desizing and refining process must be done before dyeing and after desizing and refining , there should be no impurities left such as electrolyte, antistatic finishing agent , spin finishes and blot.
2.Pre-setting
Suitable pre setting conditions ( time ,temperature and tension) helps not only in stable dimensional stability ,softness but also better dyeing results.
3.Alkali weight reduction
Alkali weight reduction s to treat the fabric with concentrated alkali at high temperature.fber molecule hydrolyse under this condition and lose some weight with change in properties, thus space occurs between crossing points and rubbing resistance relative to slippage among yarns becomes small.Alkali weight reduction makes fabric soft, liveliness, limber and improved absorption.
2.Careful selection of the dyes.
Proper dye selection which are
1.Compatible
2.Having same exhaustion rates
3.Having high wash fastness properties.
4.Good migration and levelling properties
eliminates problems regarding build-up and fastness properties.
Disperse dyes for polyester microfibers
3.Optimizing the dyebath conditions and dyeing cycle.
Optimised dyeing cycles can be worked out by controlling the temperature to account for the high rate of dyeing and to eliminate the risk of uneven dyeing.Chemicals and dyes to be added at, at least 10-20 deg.C lower temperature than normal polyester fiber dyeing. The additions of dyes must be progressive or devided at least into 4 parts. The heating rate must be slow from 40 deg C to 100 deg C. 10-20 min more holding time required at 130 deg C as compared to normal PES.
4.Proper selection of Dyeing machinery.
The dyeing machine must have the required automation to fufil the requirements of microfiber dyeing such as microprocessor controlled dosing , proper and accurate heating rate control etc.
5.Proper selection of dyebath additives
such as
Levelling agents :- A strong levelling agent which shall start working at lower temperatures.
Dispersing agents :- Higher quantities of dispersing agents are needed because amount of dyes required are more to produce the desired depth.
Chelating agents:-
Anticreasing agents,Dyebath softners/Lubricants :- Because microfiber textiles are prone to creasing , therefore use off dyebath lubricants is must.
Soaping :- In order to obtain satisfactory color effect , fabric should be soaped after dyeing .Soaping is the key process to achieve satisfactory dyeing results on polyester especially polyester / nylon microdenier fabric.
Reduction clear :-Good reduction clear process is needed to achieve satisfactory washing , rubbing and light fastness properties.
Washing :-Is required for neutralising and removing alkali after reduction clear treatment.
Softening, anti soil and antistatic treatment :-Because microdenier fiber easily stains and produces static charges, a hydrophilic ,antistatic and antisoil treatment besides softening is highly recommended to ensure fabric softness and comfortability.
Recommended Dyeing Cycle for polyester Microfibers
Dianix PLUS( Dystar) or Longsheng is a new range of five compatible, level-dyeing dyes for reliable dyeing of medium and heavy shades, especially on microfiber and weight-reduced polyester, whether applied under mild alkaline conditions to control trimer, or under conventional acid conditions.
Dianix E-PLUS" for Pale Shades on Polyester Fabrics
Fashion application of polyester
Dianix E-PLUS" for Pale Shades on Polyester Fabrics
Fashion application of polyester
Application of polyester Microfibres
Microfibers are most commonly found in polyester and nylon. Some rayon and acrylic micros are in production and available to consumers. Micros can be used alone or blended with conventional denier man-made fibers as well as with natural fibers such as cotton, wool, and silk.
In textiles
Microfibers are used in a variety of fabrics, but most commonly in dress and blouse weight garments. Suit jackets and bottom weights are becoming available. Look for micros in lingerie, rainwear, outdoor fleece and wind-resistant sportswear, as well as tents, sleeping bags, track and jogging suits. The strength of microfibers make them particularly adaptable to sueded or sandwashed finishes because of their extensive fiber surface area and the use of strong fibers like polyester and nylon. As a result, many microfibers simulate the appearance of sandwashed silk.
Other Main products for which microfiber are ideally suited:
- Microfiber Glass Cloth
- Duster/Multi-purpose Microfiber Cleaning Cloth
- Microfiber Scrubber
- Microfiber Kitchen Cloth
- Microfiber Optical & CD Cloth
- Microfiber Mops
- Microfiber Cleaning Sponge
- Microfiber Cleaning Cloths – Terry Cloths, Suede Cloths, Waffle-Weave Cloths
http://www.tex.in/education/nextiles/fib/mic/mic.html
http://ygmfranchise.blogspot.com/2007/07/cleaning-tips-microfiber.html
http://www.microfibergreen.com/is-microfiber-green-product.html
http://www.norwexnow.com/microfiber%20science.html
Saturday, January 23, 2010
Environment Management in Textile Industry
An Environment Management System (EMS) is a tool for managing the impacts of an organisation's activities on the environment. It provides a structured approach to planning and implementing environment protection measures.
Like a financial management system monitors expenditure and income and enables regular checks of a company's financial performance, an EMS monitors environmental performance. An EMS integrates environmental management into a company's daily operations, long term planning and other quality management systems.
Components of EMS
The most important component of an EMS is organisational commitment. For an effective EMS to be developed and implemented, you need commitment from the very top of the organisation, as well as all staff. Further examples of components that should be considered when developing an EMS are:
Environmental Policy
Environmental Impact Identification
Objectives and Targets
Consultation
Operational and Emergency Procedures
Environmental Management Plan
Documentation
Responsibilities and Reporting Structure:
Training
Review Audits and Monitoring Compliance
Continual Improvement
Benefits of an EMS
An EMS can assist a company in the following ways:
•minimise environmental liabilities;
•maximize the efficient use of resources;
•reduce waste;
•demonstrate a good corporate image;
•build awareness of environmental concern among employees;
•gain a better understanding of the environmental impacts of business activities; and
•increase profit, improving environmental performance, through more efficient operations.
Read more about Environmental Management Systems in Textile Industry
Environmental Management Systems
ISO 14000: environmental management: what is it? What is required? Other companys' experiences ...: An article from: Products Finishing
Iso 14000 Environmental Management
Thursday, January 7, 2010
Natural Dyes
For A complete guide to natural dyes and dyeing method,dyeing recipe and dyeing additives Click here
Complete guide to natural dyes click here
Natural dyes are a class of colorants extracted from vegetative matter and animal residues.Dyestuffs and dyeing are as old as textiles themselves. Nature provides a wealth of plants which will yield their colour for the purpose of dyeing, many having been used since antiquity.
Almost any organic material will produce a colour when boiled in a dye-bath, but only certain plants will yield a colour that will act as a dye. The plants names given below are a selection of plants that have stood the test of time, and are used widely and traditionally by natural dyers. Natural dyes fall into the following categories:
•Leaves and stems
•Twigs and prunings
•Flower heads
•Barks
•Roots
•Outer skins, hulls and husks
•Heartwoods and wood shavings
•Berries and seeds
•Lichens
•Insect dyes
The choice of mordant for a particular plant is dependant upon the material with which it will be used. It is necessary to check a recipe before using a plant, or one can experiment to see what effect a mordant has for a particular application. It is recommended that plants be grown specifically for the purpose of dyeing. Harvesting plants from the wild on a non-sustainable basis can endanger the survival of the plant. Many lichens are registered as protected organisms and it is illegal to gather them from the wild.
Almost any organic material will produce a colour when boiled in a dye-bath, but only certain plants will yield a colour that will act as a dye. The plants names given below are a selection of plants that have stood the test of time, and are used widely and traditionally by natural dyers. Natural dyes fall into the following categories:
•Leaves and stems
•Twigs and prunings
•Flower heads
•Barks
•Roots
•Outer skins, hulls and husks
•Heartwoods and wood shavings
•Berries and seeds
•Lichens
•Insect dyes
The choice of mordant for a particular plant is dependant upon the material with which it will be used. It is necessary to check a recipe before using a plant, or one can experiment to see what effect a mordant has for a particular application. It is recommended that plants be grown specifically for the purpose of dyeing. Harvesting plants from the wild on a non-sustainable basis can endanger the survival of the plant. Many lichens are registered as protected organisms and it is illegal to gather them from the wild.
Why natural dyes Here
Natural dye applications click hereNatural Dyes for Textiles and Clothes Click hereBook on Natural dyeing of textiles Click Here
How to use natural dyes click here
Natural dyeing of Textiles click here
Natural dye international click here
Natural dyes and mordants A students project
Natural dyes and thier application classes Click here
Natural dye process Click here
Natural plant dyes click here
Saturday, December 26, 2009
Tests Of Polluted Water
Color
Color in water may result from the presence of natural metallic ions (iron and manganese),
humus and peat materials, plankton, weeds, and industrial wastes. Color is removed to make a
water suitable for general and industrial applications. Colored industrial wastewaters may require color removal before discharge into watercourses.
Temperature
Due to biological treatment, if required, the temperature of wastewater should be kept between 10 and 30 C if possible. This is due to the optimum temperature that microorganisms function at.
Biochemical Oxygen demand (BOD): The strength of the wastewater is often determined by measuring the amount of oxygen consumed by microorganism like bacteria in biodegrading the organic matter. The measurement is known as the Biochemical Oxygen Demand (BOD).
Chemical Oxygen Demand (COD): This is a means of measuring the ability of wastewater to
sustain aquatic life, essential for the preservation of the environment. It also enables proper
assessment of treatment plant performance. Aquatic organisms and animals require dissolved
oxygen to flourish. The Chemical Oxygen Demand (COD) test gives an indication of the impact of
discharge waters on aquatic life by measuring the oxygen depleting nature of the discharge water.
sustain aquatic life, essential for the preservation of the environment. It also enables proper
assessment of treatment plant performance. Aquatic organisms and animals require dissolved
oxygen to flourish. The Chemical Oxygen Demand (COD) test gives an indication of the impact of
discharge waters on aquatic life by measuring the oxygen depleting nature of the discharge water.
Total suspended Solids (TSS): TSS is mainly organic in nature, are visible and can be removed from the wastewater by physical/ mechanical means e.g. screening and sedimentation. TSS is measured by filtering a certain quantity of effluent and then drying the filtrate at certain
temperature e.g. 1050C followed by weighing. TSS is expressed as parts per million or in
milligram/litre. The pore size of the filter paper is very important in estimating the TSS, the
nominal pore size 1.58 micro metre.
temperature e.g. 1050C followed by weighing. TSS is expressed as parts per million or in
milligram/litre. The pore size of the filter paper is very important in estimating the TSS, the
nominal pore size 1.58 micro metre.
Total Dissolved Solids (TDS):TDS is the sum total of all of the dissolved things in a given body of water. It is everything in the water that's not actually water. It includes hardness, alkalinity, cyanuric acid, chlorides, bromides, sulfates, silicates, and all manner of organic compounds.TDS is
referred to as the total amount of mobile charged ions, including minerals, salts or metals
dissolved in a given volume of water, and is expressed in units of mg per unit volume of water
(mg/L), or as parts per million (ppm).
referred to as the total amount of mobile charged ions, including minerals, salts or metals
dissolved in a given volume of water, and is expressed in units of mg per unit volume of water
(mg/L), or as parts per million (ppm).
Microorganisms - Microscopic living objects, which require energy, carbon and small amounts of inorganic elements to grow and multiply. They get these requirements from the wastewater and the sun, and in doing so help to remove the pollutants.
pH – A term used to express the intensity of the acid or alkalinity source. pH represents the
effective concentration (activity) of hydrogen ions (H+) in water. This concentration could be
expressed in the same kind of units as other dissolved species, but H+ concentrations are much
smaller than other species in most waters. The activity of hydrogen ions can be expressed most
conveniently in logarithmic units. pH is defined as the negative logarithm of the activity of H+
ions:
pH = -log [H+]
Sludge-The settable solids separated from the liquid during sedimentation (clarification). The
sludge is very toxic in nature and needs to be dealt with very carefully. Under no circumstances it should be mix with the environment again.
Metals
A number of metals are listed in the national environmental quality standards for industrial wastewater, including Cd, Cr, Cu, Fe, Pb, Hg, Ni and Zn. Many metals, which are usually only available naturally in trace quantities in the environment, can be toxic to humans, plants, fish and other aquatic life.
Phosphorus, Total Nitrogen, Nitrate and Ammonia
These parameters are all used as a measure of the nutrients present in the wastewater, as a high nutrient content can result in excessive plant growth in receiving water bodies, subsequent oxygen removal and the death of aquatic life.
A number of metals are listed in the national environmental quality standards for industrial wastewater, including Cd, Cr, Cu, Fe, Pb, Hg, Ni and Zn. Many metals, which are usually only available naturally in trace quantities in the environment, can be toxic to humans, plants, fish and other aquatic life.
Phosphorus, Total Nitrogen, Nitrate and Ammonia
These parameters are all used as a measure of the nutrients present in the wastewater, as a high nutrient content can result in excessive plant growth in receiving water bodies, subsequent oxygen removal and the death of aquatic life.
Sulphur and Sulphide
Textile dyeing uses large quantities of sodium sulphate and some other sulphur containing chemicals. Textile wastewaters will therefore contain various sulphur compounds and once in the environment sulphate is easily converted to sulphide when oxygen has been removed due to oxidation of BOD in the effluents. This is a problem because hydrogen sulphide can be formed which is a very poisonous gas, it also has an unpleasant smell of rotten eggs. The presence of sulphides in effluents can upset biological treatment processes.
Textile dyeing uses large quantities of sodium sulphate and some other sulphur containing chemicals. Textile wastewaters will therefore contain various sulphur compounds and once in the environment sulphate is easily converted to sulphide when oxygen has been removed due to oxidation of BOD in the effluents. This is a problem because hydrogen sulphide can be formed which is a very poisonous gas, it also has an unpleasant smell of rotten eggs. The presence of sulphides in effluents can upset biological treatment processes.
Oil and Grease
This includes all oils, fats and waxes, such as kerosene and lubricating oils. Oil and grease causes unsightly films on open water bodies and negatively affects aquatic life. They can also interfere with biological treatment processes and cause maintenance problems as they coat the
surfaces of components of an ETP.
This includes all oils, fats and waxes, such as kerosene and lubricating oils. Oil and grease causes unsightly films on open water bodies and negatively affects aquatic life. They can also interfere with biological treatment processes and cause maintenance problems as they coat the
surfaces of components of an ETP.
Zero discharge in textile dyeing
The words of Thomas fuller (Gnomologia,5451)
Neutralization
After homogenization, the solution has a pH of around 9 to 10. Neutralization of the water can be done by acid or air flow injector depending on the pH value.
Physical- chemical- treatment
If the concentration of dissolved solids is very high (sulfides, chromates, etc.) and/ or color is also in the water, the kind of treatment is various.Possible procedures:
Ultarfiltration and Reverse osmosis
Read Articles on Zero Discharge
Reuse of treated water in Textiles
Reuse of textile ETP Sludge in building material Approaching zero discharge with optimised resource management
Toward Zero Discharge: Innovative Methodology and Technologies for Process Pollution Prevention
The challenge of zero discharge: from water balance to regeneration [An article from: Desalination]
A chemo-enzymatic pathway leads towards zero discharge tanning [An article from: Journal of Cleaner Production]
“we never know the worth of water till the well is dry”
are we going to wait till that long?
Water is an essential ingredient in the textile wet processing , the availability , quality and cost are issues of concern worldwide at one hand and the issues on other hand like environmental aspects, public health, treatment and recycling cost and legislative issues regarding disposal of effluent and sludge threatening the textile industry in many countries.
The textile processing industry is mainly now shifted to the developing countries from the developing world creating a huge potential for textile exports and earning foreign currency , but unless the water is used judiciously , it would not last too long and we will run out of this precious resource very soon.
Therefore the need of the hour is to understand the extent of the problem and implement a proper water management program for the usage , treatment and disposal of effluents. Water is being a major chemical in the textile dyeing , without which dyeing is impossible, therefore we should take appropriate steps , not only to meet the statutory requirements but also to save this resource for the coming generations. The implementation of water management program also important for the textile industry ,to remain competitive and meet the customer requirement specifically in exports . It is essential to reduce the overall water requirement , effluent treatment , recycling and disposal of wastes.
The effluent from dye houses consists of a mixture of all the chemicals used in the dyeing process plus materials derived from the fabric/fiber or yarn being dyed. For cotton dyeing small fibers of cotton detached from the fabric during scouring/bleaching, dyeing and washing stages. During the scouring and bleaching process some components of the cotton fibers such as pectin, waxes and oils are also dissolved and dirt will be released. So the effluent from a dyeing unit contain among other things, sizing agents cellulose and synthetic fibers, synthetic dyes, common salt, sodium sulphate, caustic soda and soda ash, surfactants, acetic acid from neutralization stages, finishing chemicals , oxidizing and reducing agents and any auxiliaries used.
ZERO DISCHARGE
Textile processing industry is one of those identified as a potential threat to the environment because of discharge of huge quantities of waste water loaded with toxic chemicals in the form of effluents , which cause air , water and soil pollution. Although it is mandatory to install an effluent treatment plant and treat the waste water to conform with the standards laid down by the legislation, but importance of recycling is increasing day by day ,with the decreasing quality and quantity of fresh water and increasing cost.
First of all we should remember the principle of 3 R,
Reduce:- reducing the water and chemical consumption is the first step towards zero discharge. Follow few simple rules such as
1.Repair the water leaks and faulty valves.turn off running taps and hoses.
2.Turn off water supply when the machines are not running.
3.Reduce and optimise the number of steps in a processing cycle.
4.Reduce the process water , by working at a lower liquor ratios ,where less water levels can be used.use intermiitent washing instead of overflow washing.
5.Implementing maintenance plan for steam traps
6.Installing a digital monitoring system for boilers
7.Installing a peak load generator to minimize power consumption.
8.Installing screens in drain lines to reduce solids in effluents
9.Installing a digital hardness monitor in the softener system to conserve water and chemicals
10. Use counter current washing techniques in continuous washing machines.
11.Delivering training to operators to reduce power and water consumption
12. Reuse standing bath in operations such as sulphur black dyeing.
Recover
Segregate and reuse the water , which can be recycled without any treatment.
Collect hot condensate and reuse it.
Recover heat from the hot waste water and use it for heating fresh water.
Recover chemicals from the waste water , such as sizing chemicals, caustic recovery in the mercerising etc.
Effluent can be treated in a number of different ways depending on the composition of the effluent and the level of treatment required. These levels could be classified into the following types: Preliminary, Primary, Secondary, and T
Recycle
Recycling of cone-dye cooling water
Recycle air compressor cooling water
Recycling of air conditioning system water
Recycling rinse water from the bleaching, washing and softening stage
Stages in textile waste water treatment for zero discharge,
ertiary. The mechanisms for treatment can be divided into three broad categories: Physical, Chemical, and Biological. Many of these processes are used together in a single treatment plant.
Recycle
Recycling of cone-dye cooling water
Recycle air compressor cooling water
Recycling of air conditioning system water
Recycling rinse water from the bleaching, washing and softening stage
Stages in textile waste water treatment for zero discharge,
Primary treatment:-
Primary treatment is the first step in the treatment process rather than simply preparing the effluent for treatment it actual reduces the pollution potential. In the treatment of dye house effluents settling is not normally used as a primary treatment process. pH control is an important aspect of primary treatment of textile wastes as these often have extreme pHs which need to be adjusted prior to discharge in order to meet effluent standards. pH control is also important to prepare effluent for biological treatment as extreme pH can kill or inhibit microbes in treatment plants. Following are the different steps in primary treatment,
Screening, straining
This first step of treatment is to remove small particles from the process water. In this way the water will be cleaned from fibers, fluff and cotton flock. For these filters, drum screens- and fine filters are used.
This first step of treatment is to remove small particles from the process water. In this way the water will be cleaned from fibers, fluff and cotton flock. For these filters, drum screens- and fine filters are used.
Oil and grease removal
If during the step of textile treatment, solvents like white spirit or others are used they have to be removed from the wastewater. Oil Separators and oil skimmers are used to remove the oil and the other organic solvents from the wastewater so to avoid the microorganisms from being killed.
If during the step of textile treatment, solvents like white spirit or others are used they have to be removed from the wastewater. Oil Separators and oil skimmers are used to remove the oil and the other organic solvents from the wastewater so to avoid the microorganisms from being killed.
Equalization or Homogenization
This step is useful in order to mix and homogenize the wastewater. With this step, the pollution is better distributed. That makes it easier for microorganisms to treat the water. The result is a more effective biological treatment
This step is useful in order to mix and homogenize the wastewater. With this step, the pollution is better distributed. That makes it easier for microorganisms to treat the water. The result is a more effective biological treatment
Neutralization
After homogenization, the solution has a pH of around 9 to 10. Neutralization of the water can be done by acid or air flow injector depending on the pH value.
Physical- chemical- treatment
If the concentration of dissolved solids is very high (sulfides, chromates, etc.) and/ or color is also in the water, the kind of treatment is various.Possible procedures:
- Oxidation of sulfides
- Flocculation
- Color-removal with flotation
Secondary treatment
Secondary treatment biologically purifies settled effluent. Mainly bacterial micro organisms digest the effluent and remove the majority of organic compounds. Once wastewater has gone through the primary treatment stage the effluent will undergo a secondary treatment in order to remove both small suspended solids and BOD5 (five day biochemical oxygen demand) that pass through the primary treatment stage. All secondary treatment systems use a biological process to break down organic matter. Microorganisms are introduced to the wastewater and consume the organic matter, oxygen is delivered to the system ensuring microorganism survival. Oxygen delivery differs among the various systems. This biological process occurs naturally in nature, but is accelerated in secondary treatment systems. Typically 85% of BOD and suspended solids are removed during this process. Water exiting secondary treatment will still carry nitrogen, phosphorus, heavy metals, pathogens, and bacteria. For further removal of pollutants the water is transported to a tertiary treatment system and disinfection. There are a variety of secondary treatment processes; the following are conventional processes used by treatment plants:
Activated sludge
Surface-aerated basins
Trickling filter
Oxidation ponds
There are pros and cons to each of these three processes. Operational and initial costs along with space are three factors that will often determine which technique is appropriate. Space is influenced by population size and cost of land. For example, oxidation ponds require large areas of land if land is costly or needed for housing oxidation ponds are not a likely option. Additionally wastewater treatment plants need to consider maintenance, reliability, and effectiveness of the system.
Tertiary treatment
Tertiary treatment describes any additional treatment process designed to achieve even higher standards of water quality. Tertiary treatment processes can further remove suspended solids, microorganisms, inorganic minerals (like ammonia, nitrate or phosphate) and colour. Such tertiary treatments are often used to create very high quality effluents from ETPS which discharge it environmentally sensitive areas or recycled.
Ultarfiltration and Reverse osmosis
Ultra filtration and RO are based on the selective permeability of some membranes that are selective toward water and dissolved matters: at a pressure higher than the osmotic one water passes through membrane and dissolved matter is retained RO: membrane permeable to water, not to dissolved solids.
Ultra filtration membrane selectivity is due to a mechanism similar to the filtration: the dissolved matter molecules, of bigger size, don’t pas through the membrane .
In the RO, dissolved matter and water have very different transport velocity through the membrane.
Conclusion
The primary and secondary treatments are given to meet the statutary requirements . However the water after secondary treatment in not recyclable ,in order to get water for recycling the process of ultrafiltration and reverse osmosis are bieng used. This treatment is also known as tertiary treatment .The water after tertiary treatment is almost free from color,odour, COD,BOD,TDS,TSS and heavy matter impuriteis. The recovery of the water for recycling depends upon the number of stages in ultrafiltration , filtration media, and number of stages at RO. By employing a proper set up of different techniques , approximately 85%-97% of water can be reused.
Read Articles on Zero Discharge
Reuse of treated water in Textiles
Reuse of textile ETP Sludge in building material Approaching zero discharge with optimised resource management
Toward Zero Discharge: Innovative Methodology and Technologies for Process Pollution Prevention
The challenge of zero discharge: from water balance to regeneration [An article from: Desalination]A chemo-enzymatic pathway leads towards zero discharge tanning [An article from: Journal of Cleaner Production]
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