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HAZARDOUS WASTE TREATMENT IN

TANNERIES

Proma BhattacharyaRoll: 14CH60R34

THE CONCERNED INDUSTRY

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The Calcutta Leather Complex situated at Bantala, Kolkata

LEATHER MANUFACTURING3

CHEMICALS USED IN TANNING 4

Process Chemical used

Pre-tanning Surfactants, sodium sulfide, ammonium salts, formic and sulfuric acid.

Tanning Trivalent chromium salts like chromium sulfate, NaCl, sodium bicarbonate

Post-tanning Sodium formate, sodium bicarbonate, chrome syntans, resins, dyes, fillers

HAZARDOUS WASTES FROM TANNERIES

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TREATMENT METHODS ADOPTED

I. Preliminary treatment

II. Physico-Chemical Treatment

(coagulation-flocculation- sedimentation)

III. Biological treatment(high load activated

sludge)

IV. Sludge treatment and disposal

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COAGULATION-FLOCCULATION

Coagulation is the destabilization of

colloids by addition of chemicals that

neutralize the negative charges.

Coagulating chemical: aluminium

sulphate

Lime is added for pH correction.

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CONTD… 8

Flocculation is the agglomeration of

destabilized particles into a large size

particles known as flocs which can be

effectively removed by sedimentation or

flotation.

Additives used: anionic polyelectrolyte.

The effluent goes to the sedimentation

tank for settling and subsequent sludge

removal.

EFFICIENCY OF THE METHOD

About 80% of the suspended solids,

99% chromium and 40% BOD is reduced

by this.

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PERFORMANCE OF CLC-ETP 10

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CONCLUSION

Heavy metals create various health

hazards if not well-disposed.

Coagulation-flocculation is an effective

process for removal of heavy metals

from tannery wastewater.

Also, turbidity, Total suspended solids,

COD is reduced by this method.

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REFERENCES

Status Report On Calcutta Leather

Complex For Incorporation In The Portal

‘Banglar Mukh’

Common Effluent Treatment Plant

Kolkata Leather Complex Kolkata,

Indiaregional Programme For Pollution

Control In The Tanning Industry In South

East Asia Us/Ras/92/120-model Cetps

September 2001

THANK YOU