Role of Textile Effluent Treatment Plants (ETP) to Control Environmental Pollution

A case study in Jeans Knit Private Limited (JKPL), Bangalore

ETP flow chart which is followed in JKPL is shown a schematic diagram in Figure 1.

 

Primary Treatment:

Wastewater from different processes in a laundry was passed through Screen machine. Homogenized effluent was then sent to settler where sedimentation process was carried out with the dosing polyelectrolyte from specially designed automated dosing system where settleable and suspended solids were sedimented in the form of sludge which is collected in the sludge tank.

Screening:

Effluent from laundry outlet was passed to screening which comprises 1-2 mm mesh. In this process, solid objects such as stones, threads, and floating substances were separated out.

Equalization:

Screened effluent was then collected in a collection tank. and equalization process was carried out by mixer’s installed in the system. Homogenized effluent was then to passed onto settler.

Sedimentation:

Sedimentation was carried out by settlers by adding Poly electrolyte dosing through automated PLC controlled chemical dosing system. The resulting sludge settled in the bottom of the vessel which was transferred to sludge tank for sludge treatment and disposal.

Secondary Treatment:

Aeration and biological treatment are the two important stages in secondary treatment. Oxygen is required for the effluent to increase dissolved oxygen which helps biological (biomass) growth and biodegradation of organic pollutants. Major reduction of BOD and COD is carried out in Secondary treatment.

Aeration Tank:

Effluent from settler was aerated in aeration tank which was carried out by sucking atmospheric air with special centrifugal pump along with effluent. The effluent along with air was re-circulated in the system to achieve maximum aeration.

Bio-tower:

Biological growth and biodegradation were carried out in bio tower.  Media present in the bio-tower helps microorganisms to grow which will be converted to biomass by consuming organic and inorganic materials available in the effluent. .Breakdown of complex material in this process leads to a reduction in BOD and COD.

Tertiary  Treatment:

The main objective of tertiary to increase the quality of the effluent by various advanced systems and types of equipment. The final output was colorless, odorless microbes free effluent with reduced hardness TDS, BOD, and COD.

DAF (Diffused Air Filtration):

Diffused air filtration is the advanced system which uses minimal chemical dosing which leads to better treatment of effluent. Diffused air was circulated in the equipment with a minimal dosage of Polymer, PAC (Poly aluminum chloride) and Sodium hydroxide lead to flocculation where sludge was separated at the top of the equipment. The sludge separated in the system transferred to the sludge tank for further treatment disposal.

Sand and carbon filter:

The outlet from DAF which consists of suspended solids and odor. A sand filter comprising mixed grade media helps to reduce suspended particles and carbon filter comprising activated carbon reduces and removes color and odor.

Reverse osmosis (RO):

This is a water purification technology that uses a semi-permeable membrane to remove larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure. Treated water contains suspended particles (<200 µ) which will be filtered using filter bags ( 5 µ)and Filter cartridge ( 5 µ). Filtration was carried either by a two-stage array of membranes or three stage array of the membrane.RO filtration leads to an enormous decrease in TDS and hardness and removal of suspended particle.

Concluding Remarks

The quality of life depends on the ability to manage available water in the greater interest of the people. Water depletion of good quality water and environmental pollution has given tremendous importance to water management.

Joint efforts are needed by water technologists and textile industry experts to reduce water consumption in the industry. While the user industries should try to optimize water consumption, the water technologists should adopt an integrated approach to treat and recycle water in the industry.

Our motto is to save living species and its surrounding environment. Thus we must stop using chemicals and dyes, which produce a harmful effect on the biotic and abiotic factors in our eco-systems. Reduction of waste at the source is the preferred strategy instead of the traditional method of “end of pipe waste treatment”. Apart from problematic chemicals and dyes, the main pollutant is, of course, water. So, the new technologies, which aim to reduce or eliminate water, are to be conceived.

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