Leather tanneries in Pakistan produce all three categories of waste: •wastewater, •solid waste and •Air emissions.

However, wastewater is by far the most important environmental

challenge being faced by Pakistan's tanneries.

Although the exact quantity varies widely between tanneries, a normal requirement of around 50-60 liters of water per kilogram of hide is suggested.

ETPI's sample audits of tanneries in Pakistan

show that in some cases the consumption of water is as high as three times the suggested requirement.

The overall water discharge also demonstrates a high degree of seasonal and daily fluctuation.

For most part, the current practice is to discharge this water into the local environment without

any treatment.

As for the production of wastewater, over 80 per cent of the organic pollution load in BOD terms emanates from the beam house (pretanning); much of this comes from degraded hide/skin and hair matter. The beam house is also the source of all non-limed and limed solid waste such as fleshing, trimming and waste split.

As already mentioned, during the tanning process at least ca 300 kg of chemicals (lime, salt etc.) are added per ton of hides.

Excess of non-used salts will appear in the wastewater. Because of the changing pH, these compounds can precipitate and contribute to the amount of solid waste or suspended solids.

Every tanning process step, with exception of the crust finishing operations, produces wastewater. An average of 35 m3 is produced per ton of raw hide. This wastewater contains:

-salts (Cl), fat, protein, preservatives (soaking);- lime and ammonium salts, ammonia, protein

(hair), and sulphides (fleshing, trimming, bating);

- chromium(salts) and polyphenolic compounds (tanning); and

- dye and solvent chemicals (wet-finishing).

Tanneries that perform the complete tanning

procedure, produce mixed wastewater.

The composition of this wastewater is not solely

the result of separate waste streams that merge

together. The different pH’s and the different

compounds influence each others’ solubility. In

composite wastewater, compounds precipitate

while they stay dissolved in the wastewater from

the separate processes

• Discharge in underground water Most of the tanneries in Pakistan discharge there waste water in the underground water , due to which the drinking water is loosing its drinking quality n carry most of the diseases in it.Now a days it is a main cause of the many diseases e.g diarrhea ulcer etc.

• Discharge in the fresh water streams, canals Some tanneries discharge there waste water in the fresh water streams n canals as the waster from the tanneries contain the heavy metals in them , as we use them for irrigation the vegetables they accumulate in them n cause toxicity.

* Quantity of raw material : 12,000 kg/day; Volume of wastewater : 600 m3/day

** Quantity of raw material : 5,500 kg/day; Volume of wastewater : 814 m3/day

*** Quantity of raw material : 10,000 kg/day; Volume of wastewater : 110 m3 /day.

The high level of settle able matter is a major reason for the sludge in composite tannery wastewater. This sludge contains between 3.5-6.5% of solid content, 20-48% of volatile matter, and 51-74% of inorganic matter.

Solid Waste: Two types of solid wastes (tanned and untanned) are generated from leather productionprocesses.

Solid waste include dusted curing salts, raw trimmings, wet trimmings, dry trimmings, wetshavings, dry shavings, buffing, and packaging material.

It is estimated that for a tannery averaging10,000 kilograms of skins per day, a total of some 5,500 kilograms of solid waste would be produced perday. Table 2 presents a breakdown on this waste and its key characteristics.

These figures show that the solid waste produced per ton of raw hide is about 450-600 kg. About half of this contains 3% chrome on a dry matter basis.

Pretanning Tanning Finishing

Trimmings 120* 110 32

Fleshings 70-230

Wet blue split

115

Buffing dust 2

Total 190-350 225 34

*: hides not trimmed in the abattoir itself

Air Emissions: There are two sources of air pollution from

tanneries in Pakistan. The first relates to emissions from generators

(diesel-based and operated only during power breakdowns) and from boilers.

Emissions were found to be well below the NEQS level.

Ammonia emission during processing and washing of drums, though intermittent but important, has adverse effects on workers health.

Hydrogen sulphide emission during mixing of acid and alkaline wastewater in drain is also a serious health hazardous.

Segregated discharge of acidic and alkaline effluent

ROLE OF GOVERNMENT

(NILT) National Institute of Leather Technology - The only institute in Karachi which offers programs for the development of the leather sector.

No subsidiary provided by government.

Leather product development center is being put under the control of NILT to facilitate better skill development. they work with provincial government to improve quality of livestock for raw material.(2004)

Trade policy (2003-04) offers consulting services for technical up gradation and marketing.

Highly trained Korean technicians are engaged in training to Pakistan labor force