KASUR TANNERIES POLLUTION CONTROL PROJECT (KTPC)
  - A DOCUMENTARY

The concept of cleaner technology is to eliminate pollution at the production stage. The tanners are using the production technology, due to which effluent produced is of larger volumes and strengths. Thus, it is planned to educate them about the effective production processes which not only produce less waste but save cost of production. It is of ultimate benefit to tanners and operation of plant as well. The attributes of cleaner technology are:

§ Desalting of raw hides/skins using desalting table
§ Green fleshing
§ reuse of lime liquor
§ reuse of pickle liquor
§ different techniques of water saving during different processes
§ reuse of chrome liquor
§ closed door washings instead of open door washing
§ Recovery of chrome from spent chrome liquor

1. DESALTING OF RAW HIDES/SKINS

Hides/skins are preserved by using common salt. When tanners start processing they wash the hides/skins and then start further processing due to which huge quantities of salt directly drain into the effluent and increase the chloride ions in the effluent.
To reduce the salt a technique of desalting is introduced in the by using a wooden table which can be used for this purpose and most of the salt separate from hides/skins and does not go into effluent.

2. GREEN FLESHING

After liming process fleshing of hides/skins is carried out by using fleshing machine. This can also be done after soaking process which will reduce the weight of hides/skins considerably. Due to which less amount of chemicals will be used and pollution will be reduced.

3. RE-USE OF LIME LIQUOR

Liming is a process for the production of leather. In this process Sodium sulfide and lime are used which are the cause of pollution. The suggestion is that this lime liquor instead of draining should be re-used by adding some more water, lime and sulfide and regeneration of lime liquor which will save these chemicals to go directly into effluent.

4. RE-USE OF PICKLE LIQUOR

Pickling is another process which involves salt, sulfuric acid and hydrochloric acid .This liquor is also needed to be re-used in the same manner as it was explained in lime liquor re-use.

5. DIFFERENT TECHNIQUES OF WATER SAVINGS

Due to the huge quantities of water there is huge quantities of effluent which needed to be controlled. Different techniques of less water are introduced in the tanneries to minimize this effluent load.

RE-USE OF CHROME LIQUOR

Chrome is a chemical that is used in huge quantities and is essential for leather production. But chrome is very dangerous as it cannot be dissolved or destroyed and causes cancer. That is why idea is to introduce techniques either to increase the uptake of chrome in the leather or re-use this liquor. As only 60-70% chrome is used up during processing of chrome tanned leather and rest of 30-40% drain into effluent that is should be re-used.

CLOSED DOOR WASHING

During leather processing leather needs to be washed for many times and as the water is a cheap commodity in Pakistan that is why nobody cares about the quantity of water used but this is main reason of huge amounts of effluent and washing is done by using perforated door of drum with continuous supply of water. By doing closed door washing this can be prevented and huge quantity of water can be saved.

RECOVERY OF CHROME

There is another option of re-use of chrome is by recovering it at chrome recovery plant and then re-use it. This recovered chrome produces the results exactly the same as produced by normal chrome powder and at chrome recovery plant 99% of chrome is recovered.

TOXIC CHEMICALS

Sodium Sulfide, Lime, Sulfuric Acid, Hydrochloric acid, Salt, and Chrome are some of the prominent toxic chemicals in the discharge of the tannery effluent.
These chemicals are toxic and cause of different diseases like diarrhea, skin diseases and even cancer. By introducing cleaner production techniques the effect of these chemicals can be minimized as explained above.