Design ETP for textile industries with flow charts and working
The textile industry in India is one of the most important economic sectors, due to its contribution to overall industrial production. Due to its high BOD and COD value, untreated textile effluent can rapidly deplete dissolved oxygen, if it is released into surface water sources.
High BOD and COD readings indicate very hazardous effluents for biological life. The aquatic life is negatively impacted by the high alkalinity and residues of chromium used in dyes, and these factors also obstruct biological remediation procedures.
Thus, physical, chemical, and biological analyses of such effluent can be used to determine their quality. Water is used extensively during the production of textiles, and thus, toxic chemicals, dyes, acids, and starches are discharged into the water. This wastewater can pollute water, and endanger human health, as well as harm the ecosystem.
Let us learn more about effluent treatment plants for textile industries with flow chart and working function in detail, as well as the process of effluent treatment, the design and benefits.
Sources for the production of textile wastewater
To create the desired shape and final product characteristics, the textile industry uses a vast variety of raw materials, equipment, and methods. In this business, the main source of waste is the water-based effluent that is produced, throughout the various steps of wet processing of textiles.
The use of a significant amount of water, either during the actual chemical processing or during the re-processing in preparation, dyeing, printing, and finishing, is the primary factor in the creation of this effluent. In actuality, a realistic estimate has shown that 22% of the material is reprocessed in finishing, 33% of the material is dyed, and 45% of the material is treated in preparation.
Processes which result in textile wastewater
Wet and dry procedures are used to produce fibre for textiles in textile factories. The wet process creates contaminated wastewater that needs to be treated, before being released. The following steps are a part of the wet process:
1: Size: Starch, enzymes, and waxes are added to yarn during the size process, to increase its strength so it can endure strain and stress during weaving.
2: De-sizing: The fabric is either cleaned or desized once the yarn is woven. The goods used in desizing can include enzymes, oxidising agents, acids, and surfactants, depending on the chemicals used to size the yarn.
3: Scouring: Cleaning fibres by scouring is another step in the dyeing process. Use of soaps, surfactants, pectin, fats, sizes, oils, and waxes are all part of it.
4: Bleaching: It is a de-colorization technique that takes the colouring elements out of raw textile materials. Wastewater from this method contains hydrogen peroxide, sodium silicate, stabilizers, and alkaline conditions.
5: Mercerising: To strengthen fabric and enhance dye uptake, cloth is treated with a variety of chemicals, including sulphuric acid, zinc chloride, and sodium hydroxide.
6: Dyeing: Dyeing gives fibres colour and creates a variety of toxins, including salt, surfactants, metals, pigment, acids, and alkalis.
7: Printing: It causes the emission of toxins, such as the formaldehyde, solvents, metals, urea, as well as colour.
8: Finishing: It removes pollutants like solvents, softeners, waxes, and resins while transforming fabrics into useful materials.
Characteristics of textile wastewater
The usage of several chemicals, dyes, acids, and starches in the textile industry results in the production of hazardous effluent.
These used in textile manufacturing pose serious health and environmental risks. Numerous chemicals used in the production of textiles are caustic. Materials that are vulnerable can be harmed by chemicals like lye and bleach.
Because, oil is used to lubricate textile operations, the wastewater produced is oily.
Some chemicals can combine to form potentially harmful compounds. Numerous chemicals are released by the textile industry, and when they combine in wastewater, they might react.
The toxins removed from wastewater during textile effluent treatment are:
Dyeing textiles necessitates the treatment of wastewater. Because, they are poisonous and non-biodegradable, synthetic dyes pose a serious risk to the environment. These can have a negative impact on the crop output, the soil fertility, as well as human health.
The following dyes are utilised in the textile industry:
· Phthalocyanine-based dyes
· Diphenylmethane and triphenylmethane
· Dyes that are nitrated and nitrosated
· Polymethinic pigments
· Basic or cationic dyes
· Metal-based dyes
· Dissolvable colours
· Vat colours
Unwanted dye effluents are discharged into wastewater during the dyeing of textiles. These dyes can offer serious risks to aquatic habitats like seas, rivers, and lakes if wastewater is not cleaned.
They can harm the fundamental elements of aquatic habitats since they are not biodegradable. In addition, dyes prevent the light from penetrating deep within aquatic habitats, decreasing the photosynthesis in aquatic vegetation, and changing the nature of these settings.
The textile industry makes use of numerous chemicals. The following textile finishes are created with the aid of chemicals:
· Anti-bacterial coating
· Fire-resistant coating
· Finishes that resists stains
· Anti-static surface
· Easy-care surface
· Hydrophilic surface
· Non-slip surface
The following are the acids used in the textile industry:
· Phthalic acid
· Citrus acid
· Acetic acid
· Liquid nitrate
For hundreds of years, the sizing and finishing steps in the manufacture of textiles have required starch. It is a finishing compound that has historically been used to enhance the visual appeal of rayon and cotton fabrics. Additionally, it is utilised to impart yarn characteristics that help with weaving during the sizing process. It enhances the lustre of fabrics, and gets rid of wrinkles that develop during preparation.
The starches used in the textile business emit high-strength organics, which must be recycled or removed from the wastewater. The main starches used in the production of textiles are as follows:
Flow-Chart for Effluent Treatment Plant for textile industries
Wastewater treatment levels and stages of ETP for textile industry
· Preliminary stage
· Primary stage
· Secondary stage
· Tertiary (or advanced) stage
A: Preliminary treatment process of effluent treatment in textile industries
Physical separation of large contaminants like cloth, plastic, wood logs, paper, etc., occurs at the preliminary treatment level.
The following physical unit procedures are typical at the preliminary level:
Screening: To eliminate big solids like plastic, cloth, and other materials, a screen with uniformly sized apertures is utilised. Typically, a 10 mm size is employed.
Sedimentation: Gravity is used in a physical water treatment procedure to remove suspended materials from water.
Clarification: It is applied to remove particulates from liquids.
B: Primary treatment process of effluent treatment in textile industries
Removal of floating and settleable contaminants, such as suspended solids and organic waste, occurs at the first treatment level.
Methods: This treatment employs both physical and chemical techniques.
1: Chemicals are added to the wastewater during chemical operations to alter its quality, e.g., coagulation, chemical precipitation, oxidation, and pH regulation to modify the pH during the wastewater treatment process. Also, NaOH, Na2CO3, or CaCO3 should be used for acidic wastes (low pH) and H2SO4 for alkali wastes for high pH.
2: Coagulation is the process of gathering the smallest solid particles scattered in a liquid, into a bigger solid mass. Wastewater is treated using chemical coagulants like Al2(SO4)3 also known as alum or Fe2(SO4)3 to increase the attraction of small particles, causing them to coalesce into larger particles known as flocs. A chemical flocculent (often a polyelectrolyte) improves flocculation by aggregating particles into bigger flocs that settle out more quickly.
C: Secondary treatment process of effluent treatment in textile industries
1: Activated sludge process: When oxygen is given to a wastewater column, the process of aeration stimulates good bacteria, and enables them to break down organic waste.
Water treatment using activated sludge method combines aeration with extra bacteria, which break down the organic materials in the effluent. The precise calibration of the F/M ratio, makes this process exceedingly time-consuming. At the conclusion of the procedure, the sludge needs to be recycled.
2: MBBR or Moving Bed Biofilm Reactor: The MBBR is a very efficient biological treatment method that combines the use of biofilm media, and the traditional activated sludge process. Within the aeration and anoxic tanks of the MBBR process, floating high capacity medium are used.
D: Advanced or tertiary treatment process of effluent treatment in textile industries
It is the final cleaning step before wastewater is recycled, utilised again, or released into the environment.
Mechanism: It gets rid of any residual inorganic chemicals as well as elements like nitrogen and phosphorus. At this step, viruses, bacteria, and parasites which are hazardous to public health are eliminated.
1: Adsorption: During the adsorption process, wastewater molecules in liquid form are attached to a solid, such as activated carbon.
2: Alum: It is employed to aid in the removal of more phosphorus particles and to combine the residual solids for straightforward removal as a group.
3: Chlorine disinfection: By eliminating bacteria, viruses, and parasites from treated wastewater, a chlorine contact tank disinfects secondary treated wastewater. Just before it is released, sodium bisulphate is added to eliminate any leftover chlorine.
4: RO Plants: Now-a-days, RO plants are also utilized for the recycling or reuse of wastewater.
Why are ETPs required in the textile industry sector?
In addition to being necessary for drinking, clean water is also required for many other tasks like washing, cleaning, building construction, manufacturing, and other economic endeavours. The need for industries to purify water that has been impacted by their operations is significant. Thus, the ETP for textile industry is made to address industrial wastewater-related problems.
The idea of the treatment is to completely remove the COD/BOD, with the condensate produced as a result, meeting the standards for freshwater purity, as well as
· to purify industrial wastewater and repurpose it
· minimising the consumption of fresh/potable water
· to reduce more spending on water
· to adhere to the government's guidelines for the emission or discharge of environmental contaminants
· to avoid paying exorbitant fines
· in order to protect the environment from pollution and promote sustainable development
How to design an ETP for the textile industry?
The ETP's size and design are determined by:
· effluent that is discharged by enterprises, both in quantity and quality
· availability of land
· the financial aspects of construction, and operation, and maintenance
Area measurement is based on:
· treated wastewater's quality and flow rate
· useful modifications in treatment procedures
· common effluent treatment plants (CETPs) are favoured over ETPs when there is a lack of available land
Benefits of ETPs for textile industries
· Faster wastewater treatment
· Longer lifespan
· Reduced hydraulic retention time (HRT)
· Greater hydraulic capacity
Learn more about our options for treating textile industry wastewater
Wastewater or effluent from the textile industry is harmful to the environment and to people's health. To prevent wastewater pollution, poisonous and dangerous substances that are released into the water, during textile production must be eliminated.
Netsol Water provides effective programmes and systems for treating textile industry effluent. We provide outstanding wastewater solutions for any sector with high-quality, dependable products and a knowledgeable engineering group. Our equipment offers unmatched results to assist textile industries, in efficiently treating their wastewater.
Therefore, textile factories can count on the safest and most efficient wastewater treatment method with Netsol Water Solutions. To find out more about our alternatives for treating textile wastewater, get in touch with us. Call us at +91 9650608473 or email at email@example.com for further information.