Water Purification Process in Textile Industry

Last Updated on 04/02/2021

Water Purification:
Water purification is the collective name for a group of processes that make water more suitable for drinking, medical use, industrial use, and so on. A water purification process is designed to remove or reduce existing water contaminants to the point where the water is fit for use.

Conventional softening treatment plant may not remove the impurities in water to the recommended permissible level. Demineralized or reverse osmosis technique is needed for removal of TDS from water but is costly. Water purification in the process house normally consists of flocculation, sedimentation, filtration and ion exchange. Hard water is normally softened using one or combination of methods. In water purification, the role of adsorption is significant. The fact that we can get almost clean and pure groundwater (barring cases of some specific contamination) is largely because of the natural adsorbents of soil.

water purification in textile industry
Fig: Water purification in textile industry

Textile industry, specially textile wet processing industry need huge consumption of water for processing different steps like, desizing, scouring, bleaching, dyeing, washing etc. So before using water different treatment have to done. In textile wet processing industry different types of methods are used to purify water. In this article I will discuss some water purification process those are frequently used in textile wet processing industry.

Water Purification Process for Textile Wet Processing Industry

Soda-alum process
Hard water is first pumped into the reaction tank and then aluminium sulphate is added to it as floculant. About 20-30 min is allowed to react and then the impurities are allowed to settle for about 30 min before filtration.

Soda-alum process

Many floculants need alkali as an assistant floculant. If additional alkali is not added, the total alkalinity is reduced and part of aluminium sulphate, being water soluble may pass through the filter. As aluminium hydroxide and metals precipitate downwards, clear water arrives at the top and is decanted.

Lime-soda process
In this process lime and sodium carbonate are added to precipitate the calcium and magnesium salts as temporary hardness.

Lime-soda process

For permanent hardness the reactions are

permanent hardness the reactions

The softened water is usually slightly alkaline with 1-4 degree residual hardness.

Base exchange process
When hard water is passed through a bed consisting of zeolites, which are synthetic material systems composed of complex sodium, aluminium and silicate salts (Na2Z), the calcium and magnesium ions are exchanged. The displacing reactions for temporary hardness are:

Base exchange process

For permanent hardness the reactions are:

permanent hardness the reaction

The process is reversible and the bed (Na2Z) can be regenerated by passing concentrated salt solution. This method of water softening yields a very soft water (0.5-1 o hardness).

water softening

Water softening by demineralisation systems can be accomplished using either mixed bed (both cation and anion resin in one bed) or two bed system (resins remain seperated according to their charges). The active sites of the resins are limited and the sites are filled when water passes through these columns and must be regenerated again. Their ion-exchange capacity is greater than that of zeolite.

Nowadays nanotechnology is used in water purification process by nanoparticles.

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  3. Implementation of Effluent Treatment Plants for Wastewater and Effect of Untreated on Environment
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