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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content. The Chrome t<strong>an</strong>ned waste conta<strong>in</strong>s Chromium <strong>in</strong> trivalent form but it was found that when <strong>the</strong><br />
solid wastes are used <strong>in</strong> mak<strong>in</strong>g poultry feed <strong>the</strong> Chromium is converted to hexavalent form which is<br />
carc<strong>in</strong>ogenic. The mix<strong>in</strong>g <strong>of</strong> this metal <strong>in</strong> poultry feed could produce serious hum<strong>an</strong> health problems. It is<br />
estimated that for a t<strong>an</strong>nery produc<strong>in</strong>g on <strong>an</strong> average 10,000 kilograms <strong>of</strong> sk<strong>in</strong>s per day, a total <strong>of</strong> about<br />
5,500 kilograms <strong>of</strong> solid waste would be produced per day. Table 2 presents a breakdown on this waste<br />
<strong>an</strong>d its key characteristics with comments.<br />
Type <strong>of</strong><br />
Solid Waste<br />
Rate <strong>of</strong><br />
Generation<br />
Characteristics <strong>of</strong> Solid Waste<br />
Dusted Salt 0.1 kg/sk<strong>in</strong> Conta<strong>in</strong>s around 120 gm/kg <strong>of</strong><br />
moisture, 120 gm/kg <strong>of</strong> volatile<br />
matter, 450 gm/kg <strong>of</strong> salt.<br />
Raw<br />
Trimm<strong>in</strong>gs<br />
Table 2: Solid Waste <strong>in</strong> T<strong>an</strong>neries<br />
Comments<br />
Contam<strong>in</strong>ated with blood, hair, dirt <strong>an</strong>d bacteria. Partly<br />
reused <strong>in</strong> cur<strong>in</strong>g <strong>an</strong>d <strong>the</strong> rest is <strong>in</strong>discrim<strong>in</strong>ately dumped <strong>in</strong><br />
undeveloped l<strong>an</strong>ds near <strong>the</strong> t<strong>an</strong>neries.<br />
0.024 kg/sk<strong>in</strong> Prote<strong>in</strong>s The sk<strong>in</strong>s are trimmed (especially at legs, belly, neck, <strong>an</strong>d<br />
tail parts) <strong>in</strong> order to give <strong>the</strong>m a smooth shape. The<br />
trimm<strong>in</strong>gs are usually sold to soap <strong>an</strong>d poultry feed<br />
production<br />
Flesh<strong>in</strong>g 0.25 kg/sk<strong>in</strong> Conta<strong>in</strong>s around 240 gm/kg <strong>of</strong><br />
prote<strong>in</strong>s, 200 gm/kg <strong>of</strong> fats, 3 gm/kg<br />
<strong>of</strong> sulphide.<br />
Wet<br />
Trimm<strong>in</strong>g/<br />
Wet<br />
shav<strong>in</strong>g<br />
Dry<br />
Trimm<strong>in</strong>gs/<br />
Dry<br />
Shav<strong>in</strong>g/Bu<br />
ff<strong>in</strong>g Dust<br />
Assorted<br />
Refuse<br />
Source: ETPI Survey<br />
0.14 kg/sk<strong>in</strong> Conta<strong>in</strong>s around 240 gm/kg <strong>of</strong><br />
prote<strong>in</strong>s, 30 gm/kg <strong>of</strong> fats, 15 gm/kg<br />
<strong>of</strong> chromium oxide<br />
0.06 kg/sk<strong>in</strong> Conta<strong>in</strong>s around 300 gm/kg <strong>of</strong><br />
prote<strong>in</strong>s, 130 gm/kg <strong>of</strong> fats, 30<br />
gm/kg <strong>of</strong> chromium oxide<br />
No consistent<br />
qu<strong>an</strong>tity<br />
Primarily cartons, bags, drums, etc.<br />
This is <strong>the</strong> flesh material <strong>of</strong> limed sk<strong>in</strong>s. It is usually sold<br />
to soap <strong>an</strong>d poultry feed makers.<br />
After chrome t<strong>an</strong>n<strong>in</strong>g, sk<strong>in</strong>s or split hides are shaved to<br />
proper thickness. This operation produces solid waste<br />
conta<strong>in</strong><strong>in</strong>g chrome. Secondary users <strong>in</strong>clud<strong>in</strong>g poultry<br />
feed makers, usually collect <strong>the</strong>se shav<strong>in</strong>g from <strong>the</strong><br />
t<strong>an</strong>ners.<br />
Secondary users, <strong>in</strong>clud<strong>in</strong>g poultry feed makers, collect<br />
cutt<strong>in</strong>gs <strong>an</strong>d dry trimm<strong>in</strong>gs <strong>an</strong>d buff<strong>in</strong>g dust <strong>of</strong> <strong>the</strong> lea<strong>the</strong>r<br />
from <strong>the</strong> t<strong>an</strong>neries.<br />
This is normally sold separately (<strong>in</strong> bulk) <strong>in</strong> <strong>the</strong> retail<br />
market.<br />
Air Emissions<br />
In t<strong>an</strong>neries air emissions are produced from <strong>the</strong> stacks <strong>of</strong> boilers <strong>an</strong>d generators <strong>an</strong>d dur<strong>in</strong>g <strong>the</strong> process<strong>in</strong>g<br />
<strong>of</strong> lea<strong>the</strong>r. Emissions from <strong>the</strong> stacks are well with<strong>in</strong> <strong>the</strong> limits <strong>an</strong>d pose no serious <strong>environmental</strong> impact.<br />
But hydrogen Sulphide <strong>an</strong>d ammonia gases which are emitted dur<strong>in</strong>g different processes are a health<br />
hazard for <strong>the</strong> workers.<br />
ENVIRONMENTAL IMPACTS OF POLLUTANTS<br />
Out <strong>of</strong> <strong>the</strong> three wastes mentioned, air emissions are very low as compared to <strong>the</strong> st<strong>an</strong>dards mentioned <strong>in</strong><br />
NEQS whereas <strong>the</strong> solid wastes are used <strong>in</strong> preparation <strong>of</strong> poultry feed which pose health problems. The<br />
wastewater is a serious threat to <strong>the</strong> environment. T<strong>an</strong>neries are dispos<strong>in</strong>g <strong>of</strong> <strong>the</strong>ir wastewater <strong>in</strong>to dra<strong>in</strong>s,<br />
which f<strong>in</strong>ally f<strong>in</strong>d its way <strong>in</strong>to natural water bodies. Therefore major <strong>environmental</strong> problems are l<strong>in</strong>ked<br />
with <strong>the</strong> wastewater <strong>of</strong> t<strong>an</strong>neries.<br />
The pH <strong>of</strong> directly discharged t<strong>an</strong>nery effluent varies between 3.5 to 13.5. Water with a low pH is<br />
corrosive to water-carry<strong>in</strong>g systems <strong>an</strong>d c<strong>an</strong> lead to metal dissolv<strong>in</strong>g <strong>in</strong> <strong>the</strong> water. The high pH water c<strong>an</strong><br />
cause scal<strong>in</strong>g <strong>in</strong> <strong>the</strong> sewers. Also large fluctuation <strong>in</strong> <strong>the</strong> pH value is detrimental to some aquatic species.<br />
The large qu<strong>an</strong>tities <strong>of</strong> prote<strong>in</strong>s <strong>an</strong>d <strong>the</strong>ir degrad<strong>in</strong>g products form<strong>in</strong>g a major part <strong>of</strong> <strong>the</strong> wastewater c<strong>an</strong>