Therefore, we need a treatment plant where hard water is softened by various techniques to make it suitable for pre-treatment, dyeing and finishing. Then, the treatment plant will help us obtain quality soft water for the dyeing and finishing processes. Since the cleaning plant is an essential element in the dyeing industry, anyone studying textile engineering must know the basic process and mechanism of the cleaning plant.
As part of a highly efficient production system, the cleaning plant plays an important role in determining product quality in wet textile processing.
Literature Review
- Water
- Sources of water
- Surface water
- Under river flow
- Ground water
- Frozen water
- Water Is considered as the life line of the wet processing
- Water treatment
- Water hardness
- Sources of hardness
- Temporary hardness
- Permanent hardness
Surface water is naturally replenished by precipitation and is naturally lost through discharge to the oceans, evaporation and subsurface seepage. Subsurface water can be viewed in the same way as surface water: supply, drainage and storage. In addition, if the surface water source is subject to significant evaporation, an underground water source may become saline.
Humans can increase input to a groundwater source by building reservoirs or retention ponds.
Carbonate and non-carbonate hardness
Total permanent water hardness expressed as equivalent to CaCO3 can be calculated with the following formula: Total Permanent Hardness.
Calcium and magnesium hardness
HARDNESS MEASUREMENTS
- Determination of water hardness
- Degree of Hardness
- Conversion table for water hardness units of measure
Gradual addition of the potassium oleate solution is continued until the agitation of the solution produces a reasonably permanent foam. The equilibrium constants are large and ensure quantitative formation of the colorless complexes by adding EDTA to a solution containing calcium and magnesium ions. At the beginning of the titration, the large concentrations of calcium and magnesium ions ensure that all the dye indicator is in the form of the red complexes with these metals (Ca–Dye–, Scheme 8.6).
By definition, water hardness is a characteristic value of dissolved salts found in water (calcium and magnesium hydrogen carbonate, °dH = 0.357 meq/l).
Water Quality For Dye House
1 meq/l hardness means that 1 liter of water contains 1 meq, i.e. 1 mg equivalent weight of dissolved hardness minerals (Ca and/or Mg). 1 °e, which is 1 English degree of hardness, means that 0.8 liters of water contains dissolved hardness minerals (Ca and/or Mg), corresponding to 10 mg CaO. 1 °f (°tH), i.e. 1 French degree of hardness, means that 1 liter of water contains dissolved hardness minerals (Ca and/or Mg), corresponding to 10 mg CaCO3.
1 ppm CaCO3 hardness means that 1 liter of water contains dissolved hardness minerals (Ca and/. or Mg), corresponding to 1 mg CaCO3.
WATER SOFTENING
- Soda- Lime Process
- CONVENTIONAL LIME-SODA ASH TREATMENT
- EXCESS LIME TREATMENT
- SPLIT TREATMENT
- Details of Water Softening with Soda- Lime process
- Carbon Dioxide Demand
- Removal of Hardness
- Removal of Carbonated hardness
- Removal of Non-carbonate Hardness
- Re-carbonation
- Two-Stage Softening
- Single-Stage Softening
- Sludge
- Sludge Removal
- Calculations
- Conversion Method
- Monitoring
- Chemicals Used in Lime Softening
- Types of Lime
- Lime Handling and Storage
- Soda Ash
Just enough lime and soda is added to the water to raise the pH to between 10.3 and 10.6 and calcium hardness will be removed from the water (but minimal magnesium hardness will be removed). Extra lime will raise the pH above 10.6 to help magnesium hydroxide precipitate from the water. Split treatment can reduce the amount of carbon dioxide required to re-carbonate the water, as well as provide a saving in lime feed.
Since calcium carbonate and magnesium hydroxide are not completely insoluble, the water obtained has a residual hardness of not less than 20 ppm CaCO3. Once the carbon dioxide requirement is met, the lime is free to react with and remove carbonate hardness from the water. However, if non-carbonate hardness is also to be removed from water, soda ash should be added to the water along with lime.
In general, enough carbon dioxide is added to reduce the pH of the water to less than 8.7. In both calculation methods, the doses of lime and sodium carbonate depend on the carbonate and non-carbonate hardness of the water. The total dosage of sodium carbonate is determined in the same way by calculating the sum of the amounts required to remove the non-carbonate material from the water.
The hardness of the water will determine the amount of chemicals that need to be added to soften the water. Temperature affects the speed of the reaction and the amount of hardness the water will retain. After softening, the Langelier Index of the water should be tested to ensure that the water is not corrosive.
Sodium carbonate (Na2CO3) only exists in one form and requires no treatment before being added to the water.
DESIGN CONSIDERATIONS
Soda dust irritates the eyes and nasal mucosa, so the operator must wear protective clothing, goggles and a dust mask. In addition, areas where soda ash is used must be provided with a ventilation system to cope with dust.
Water softening with Ion exchange methods
The removal of the alkaline earth metal ions is more effective the greater the surface area of the zeolite particles in contact with the water. Although the calcium and magnesium ions in the water are replaced by sodium ions, they are relatively harmless in textile processing. Suspension polymerization of the styrene and divinylbenzene produces the crosslinked polymer in the form of small beads.
They can absorb cations and release hydrogen ions, or, in the form of their sodium salts, exchange sodium ions with other cations in water. Each species will have associated counter anions that exchange with the anions in the solution in contact with the resin. The selectivity of the resin determines how strongly it binds a particular ion and therefore the ease of its exchange.
In addition to these two properties, the degree of swelling of the resin in contact with water must be limited. Resin capacity and water ion content determine when regeneration will be required. One of the problems of ion exchange beds is the retention of suspended matter and living organisms in the water in the column.
Lime softening Precipitative lime softening is a process in which the pH of the water is raised (usually by the addition of lime or soda ash) to precipitate high concentrations of calcium and magnesium. Bacteriophage MS2 was sensitive to lime softening conditions, showing more than 4-log inactivation within 2 h in the pH range of 11-11.5.
Demineralization Softening Process
Mixed Bed Resins
Degasser
Reverse Osmosis Plant (RO Plant)
If a pressure (P) greater than the osmotic pressure (π) is applied to the higher density solution (lower density solvent), the solvent molecules pass through the semi-permeable membrane from higher density solution to lower density solution. In an RO installation that uses the reverse osmosis phenomenon, salt-free water is extracted from the raw water after sand filtration. Steam air preheaters require some steam, which will reduce the efficiency of the power plant.
After using the ultrafiltration unit for a long time, backwash is required, and then it is washed again with water and dried. In the channel, the water is mixed with HCL (for pH control, as the water coming from the RO plant or RO permeate must have a pH of around 6.0) and SMBS (Sodium Metabisulphate) [Na2S2O5]. It is also mixed with an anti-scale reagent (AS) that reacts with those chemicals that form scale inside the canal.
In this stage of boiler feed water treatment, the water is supplied to the RO unit by means of a H/P pump, where after successive filtration of the 1st & 2nd stage RO, it is fed to the degassing unit. Deaerator is an open contact type heater where dissolved oxygen in the feed water is removed as much as possible by mechanical means. The partial pressure of oxygen in the air is high (since air contains almost 21% oxygen by volume) than the partial pressure of dissolved oxygen in the feed water.
Heating increases the partial pressure of dissolved oxygen in the feed water and significantly decreases solubility. But instead of air, LP steam is blown from bottom to top and feed water is poured from top to bottom.
Chapter: 03
Study and Survey
- Study and Survey
- Knit Concern Group
- Raw water reserve Tank
- Centrifugal Pump
- Multi-grade filter
- Active Carbon Filter
- Chemistry involved
- Hamid Fabrics Ltd
- R.L. Tex Limited
- Stone Tank)
- Resign Tank)
- Description of main Functional Part
- Chemistry involved in WTP
- Layout plan of WTP of R.L. Tex Ltd
- Internal structure of tank 1(stone tank), tank 2 (resin tank)
- Hardness Testing for Three industry
This pump supplies the raw water from the raw water reserve tank to the multigrade filter. Booster pressure pump: This pump supplies the soft water from the soft water reserve tank with pressure to where necessary. In this tank, about 3002 kg of salt is added after every 15 minutes to regenerate the resin through the following reaction.
Here, ions of resin are exchanged with metal ions of hard water and thus water is purified. Soft water Tank ; Soft water is stored here and then supplied to the boiler and dyeing. Water then enters a sand and stone filter and is cleaned of dirt, dust and sediments and undissolved solid matter.
Then water enters a set of ion exchange resins where hard water is purified by exchanging its metal ions such as calcium ions and magnesium ions with sodium ions from ion exchange resin where the next reaction takes place. Water is pumped from this soft water tank to supply the water to boiler and paint house.
Water Hardness Test
Procedure
Chapter: 04
Discussion of results
Input & Output Quality of water
Difference
Chapter: 05
Conclusion
It is estimated that at least 80-100 liters of water are needed to process 1 kg of textile. Therefore the water treatment plant is one of the most important units in wet textile processing technology that determines the outcome of future processes. Water quality is a determining factor in the textile finishing section. Since the fibers are very sensitive to the quality of the water used during processing, it is highly recommended to avoid the use of hard water at all costs.
It thus helps to achieve better dyeing efficiency, less color wastage, correct pre-treatment and post-treatment. It also makes the overall dyeing process economical and thus helps to achieve maximum profit. Water treatment plants also maintain a better boiler condition even after being used for a long time.
Therefore, proper attention must be paid to get the most benefit from a water treatment plant. In textile dyeing department, it is strongly recommended to use water of a predetermined quality that is free from hardness, odor and other impurities. There is a standard for the quality of paint house water that every industry must maintain if it wants to get the desired quality.
The water treatment plant must be environmentally friendly, therefore the waste from the water treatment plant requires further processing in the ETP. So, if we want to survive the challenge to produce quality textile products without hampering the environment, we need to use an efficient water treatment plant that will generate the best quality soft water for all dyeing and finishing processes.
