Tannery and Chrome Chemicals Manufacturing Sector

Raw Materials/Resources

Animal skin consists of epidermis, a layer of fatty tissue called areolar and inner corium. The semi-soluble protein, called ‘collagen’ present in corium is converted into highly durable leather through tanning operations.

Skin of cows and buffaloes is called hide. Hides are 1-3 square meter (m2) in size and weigh about 10-20 kilograms (kg).

Skin of goats and sheep is called skin. Skins are smaller in size, 0.4 – 0.5 m2 and lighter in weight around 1-2 kg.

Slaughtered hides and skins contain 60-70% moisture which makes these liable to bacterial attack, which in turn decomposes the hides and skins.

The flow diagram below shows

• the major inputs such as water, chemicals in each sectional operation starting from soaking, liming, fleshing, deliming, pickling, vegetable/ chromium tanning, etc till finishing
• the mode of operation and equipment used such as pits, paddle, drums, type of machines operated
• the waste discharges from each sectional operation such as waste water fleshings, waste trimmings and the major constituents in the waste water in terms of TDS, COD, BOD

Input vs. Output in the Tanneries