an assessment of environmental concerns in the leather industry
an assessment of environmental concerns in the leather industry
an assessment of environmental concerns in the leather industry
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lime is used to make hair loose. Unw<strong>an</strong>ted flesh is removed with <strong>the</strong> help <strong>of</strong> flesh<strong>in</strong>g mach<strong>in</strong>es after<br />
lim<strong>in</strong>g process. To prepare limed sk<strong>in</strong> for t<strong>an</strong>n<strong>in</strong>g, <strong>the</strong> sk<strong>in</strong>s are delimed us<strong>in</strong>g Ammonium Sulphate <strong>an</strong>d<br />
<strong>the</strong>n sk<strong>in</strong>s are washed. Bat<strong>in</strong>g is done for fur<strong>the</strong>r purification <strong>of</strong> hide. After that degreas<strong>in</strong>g is done with<br />
<strong>the</strong> help <strong>of</strong> detergents. T<strong>an</strong>n<strong>in</strong>g process starts with pickl<strong>in</strong>g which is <strong>the</strong> treatment <strong>of</strong> sk<strong>in</strong> with acids <strong>an</strong>d<br />
salts to br<strong>in</strong>g it to desired level <strong>of</strong> pH. T<strong>an</strong>n<strong>in</strong>g may be def<strong>in</strong>ed as <strong>the</strong> treatment <strong>of</strong> sk<strong>in</strong> for preservation.<br />
Chrome t<strong>an</strong>n<strong>in</strong>g uses Chromium Sulphate as t<strong>an</strong>n<strong>in</strong>g agent. T<strong>an</strong>n<strong>in</strong>g process stabilize <strong>the</strong> collagen<br />
network <strong>of</strong> sk<strong>in</strong>. After t<strong>an</strong>n<strong>in</strong>g sk<strong>in</strong>s are called wet blue <strong>an</strong>d are stored for sometime <strong>an</strong>d <strong>the</strong>n <strong>the</strong>y are<br />
sorted out accord<strong>in</strong>g to quality. If hides <strong>of</strong> cows or buffaloes are be<strong>in</strong>g used for lea<strong>the</strong>r m<strong>an</strong>ufactur<strong>in</strong>g,<br />
<strong>the</strong>n after this <strong>the</strong>y are sliced to give desired thickness. This process is not carried out on <strong>the</strong> sk<strong>in</strong>s <strong>of</strong> goats<br />
or sheep. After this <strong>the</strong> hair side <strong>of</strong> <strong>the</strong> wet blue are shaved to give <strong>the</strong> desired thickness.<br />
In order to give desired s<strong>of</strong>tness, color, strength, <strong>an</strong>d quality to <strong>the</strong> lea<strong>the</strong>r wet blue sk<strong>in</strong>s are processed<br />
fur<strong>the</strong>r through wet f<strong>in</strong>ish<strong>in</strong>g process. Fat liquor<strong>in</strong>g process is carried out to impart desired s<strong>of</strong>tness <strong>an</strong>d<br />
dye<strong>in</strong>g is to give it a color. After wet process different dry<strong>in</strong>g processes are carried out to dry <strong>the</strong><br />
processed lea<strong>the</strong>r. These processes consist <strong>of</strong> smay<strong>in</strong>g/sett<strong>in</strong>g, vacuum dry<strong>in</strong>g, stack<strong>in</strong>g/toggl<strong>in</strong>g,<br />
buff<strong>in</strong>g/shav<strong>in</strong>g, trimm<strong>in</strong>g, press<strong>in</strong>g, <strong>an</strong>d segregation <strong>of</strong> <strong>the</strong> lea<strong>the</strong>r. F<strong>in</strong>ally f<strong>in</strong>ish<strong>in</strong>g processes are carried<br />
out to impart durability <strong>an</strong>d beauty to <strong>the</strong> lea<strong>the</strong>r. The chemicals used <strong>in</strong> <strong>the</strong> lea<strong>the</strong>r <strong>in</strong>dustry c<strong>an</strong> be<br />
divided <strong>in</strong>to three broad categories:<br />
1. Pre-t<strong>an</strong>n<strong>in</strong>g Chemicals<br />
2. T<strong>an</strong>n<strong>in</strong>g Chemicals<br />
3. F<strong>in</strong>ish<strong>in</strong>g Chemicals<br />
Pre-t<strong>an</strong>n<strong>in</strong>g chemicals are used to cle<strong>an</strong> <strong>an</strong>d prepare sk<strong>in</strong>s for <strong>the</strong> t<strong>an</strong>n<strong>in</strong>g process <strong>an</strong>d <strong>the</strong>y are mostly<br />
washed away with <strong>the</strong> wastewater. T<strong>an</strong>n<strong>in</strong>g chemicals react with <strong>the</strong> collagen fibers <strong>of</strong> <strong>the</strong> sk<strong>in</strong> to convert<br />
<strong>the</strong>m <strong>in</strong>to lea<strong>the</strong>r. These chemicals are reta<strong>in</strong>ed <strong>in</strong> <strong>the</strong> sk<strong>in</strong> but a good amount <strong>of</strong> <strong>the</strong>se is discharged <strong>in</strong>to<br />
wastewater. Chrome Sulphate is <strong>the</strong> basic t<strong>an</strong>n<strong>in</strong>g chemical. Apart from be<strong>in</strong>g expensive, Chrome<br />
Sulphate is also a serious pollut<strong>an</strong>t. F<strong>in</strong>ish<strong>in</strong>g chemicals are used to impart certa<strong>in</strong> properties to <strong>the</strong> lea<strong>the</strong>r<br />
like s<strong>of</strong>tness, color, appear<strong>an</strong>ce etc. Like t<strong>an</strong>n<strong>in</strong>g chemicals f<strong>in</strong>ish<strong>in</strong>g chemical also get discharged <strong>in</strong>to<br />
wastewater. Only those chemicals are fully reta<strong>in</strong>ed which are applied as surface coat<strong>in</strong>g. A large amount<br />
<strong>of</strong> water is used <strong>in</strong> whole m<strong>an</strong>ufactur<strong>in</strong>g process. The collected data shows 50-150 liter water is used for<br />
conversion <strong>of</strong> one kg <strong>of</strong> raw sk<strong>in</strong> <strong>in</strong>to lea<strong>the</strong>r. In t<strong>an</strong>n<strong>in</strong>g process water is used as carrier to facilitate<br />
different chemical reactions <strong>an</strong>d after completion <strong>of</strong> process <strong>the</strong> water leaves <strong>the</strong> system as wastewater <strong>in</strong><br />
<strong>the</strong> same qu<strong>an</strong>tity as added to <strong>the</strong> system. Ground water is ma<strong>in</strong>ly used as process<strong>in</strong>g water.<br />
POLLUTANTS<br />
All <strong>the</strong> three categories <strong>of</strong> waste solid, liquid, <strong>an</strong>d gaseous, are emitted by <strong>the</strong> lea<strong>the</strong>r <strong>in</strong>dustry <strong>in</strong> <strong>the</strong> form<br />
<strong>of</strong>:<br />
1. Wastewater<br />
2. Solid Wastes<br />
3. Air Emissions<br />
The results <strong>of</strong> <strong>environmental</strong> audit<strong>in</strong>g are described below:<br />
Wastewater<br />
Water is used as <strong>the</strong> carrier for chemicals to render <strong>the</strong> cle<strong>an</strong><strong>in</strong>g <strong>of</strong> raw hides <strong>an</strong>d sk<strong>in</strong>s. The water after<br />
completion <strong>of</strong> <strong>the</strong> process is dra<strong>in</strong>ed out <strong>in</strong> <strong>the</strong> same qu<strong>an</strong>tity as it was used <strong>in</strong> <strong>the</strong> process. Normally water<br />
consumption <strong>of</strong> 50 liter/kg is recommended for t<strong>an</strong>neries but it is found that t<strong>an</strong>neries generally consume