You might be wearing or using one of its products while reading this blog. It can be a watch, bag, belt, pants, jacket, shoes, a purse or a wallet, etc. Yes, I am talking about the Tannery Industry which is one of the largest in the world. In India, it is one of the top 10 foreign exchange-earners and is the second-largest producer in the world after China. However, that’s not what should grab your eyes, instead, it’s the amount of waste and pollution it generates that should be a matter of concern.
Production of leather involves raw materials such as hides of cow, buffalo, goat and sheep going through different stages of tanning. But, it generates huge quantities of waste in the process, for example, if 1000 kg of rawhide is being processed, it will generate around 850 kg of waste and only 150 kg of it gets converted into leather.
Stages of Tanning generating Wastewater
- Soaking
- Liming & Unhairing
- Fleshing
- De-liming & Bating
- Pickling
- Chrome-tanning
- Shaving
- Re-tanning & Dying
- Fat-liquoring
- Post-tanning & finishing process
Types of Chemicals used
- Alkalis
- Tannins
- Acids
- Chromium salts
- Solvents
- Surfactants
- Sulfonated oils
- Metal-organic dyes
With production and usage of water and chemicals at each stage of the tanning process, the Tannery industry is one of the most polluting industrial sectors in India, discharging a total quantity of around 50,000 cubic metres per day of effluents containing a high concentration of organic pollutants.
Characteristics of the generated wastewater
The generated wastewater is measured under the following parameters
- pH Levels
- Alkalinity
- Chromium Levels
- Chemical Oxygen Demand (COD)
- Biological Oxygen Demand (BOD)
- Chlorine Levels
- Suspended Solids
- Dissolved Solids
Stages of Wastewater Treatment in a Tannery Industry
- Mechanical Treatment - removal of coarse material through screening. This stage can remove up to 30-40% of gross suspended solids.
- Physico-Chemical Treatment - chrome precipitation and sulphide treatment. This treatment also includes Coagulation and Flocculation which helps in the removal of considerable levels of COD and Suspended Solids.
- Effluent Treatment - It involves flow segregation which helps in the treatment of wastewater, particularly for sulphide and chrome containing liquors.
- Post-purification, sedimentation and sludge-handling - In this stage, the sludge gets separated from the water by gravity settlement through filter presses.
ROCHEM India offers state-of-the-art services in setting up wastewater treatment plants for tannery industries. They provide customised solutions for treating each of the specific characteristics of the wastewater generated during the production of leather which further helps in the reuse of water and thereby solving the rising issue of releasing wastewater into the natural water streams.
Save, Recycle & Reuse Water, install your wastewater purification plant now :
E-mail - sales@rochemindia.net
Call - +91 (22) 6704 9000
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