waste, reduction in dissolved oxygen takes place by microbial decomposition which
adversely affects the life of aquatic animals (Balasubramanian and Pugalenthi 2000),
(Song et al. 2000), (Mwinyihija et al. 2006).
Tanyard process viz. pickling, chrome tanning, leads to generation of acidic and
colored wastes. During vegetable tanning, waste consists of organic matter, whereas
high amounts of chromium are formed as waste in case of chrome tanning.
16.3.2 Solid Waste
As per European Commission, the amount of solid waste produced depends on
different type of factors, such as type of leather produced, technique applied, and
source of hides and skins (Basegio et al. 2002). Waste in solid form generated in
tannery can be divided into following forms:
– Non-proteinous waste.
– Non-collagenous protein waste.
– Tanned collagen.
– Untanned collagen.
On average, only 20% weight of hide is transformed into leather, and the
remaining goes as waste. Only 200 kg out of 1 ton of hides gets converted into
finished leather, whereas the remaining gets discharged as waste in form of waste
that contains blood, manure, protein, greases, and fat (Cooray 1999). A part of solid
waste or byproducts fixed consumers in the gelatin, textile, glue, and artificial leather
industry. Approximately, 35% of the original protein material comes out as effluent
tannery sludge, flashings, showings, and brimming. Only a small fraction of solid
waste produced in different tannery steps is utilized due to insufficient market
(Cheda et al. 1984).
16.3.3 Gaseous Waste
Tanneries are well known to discharge dust, odorous gases, and smoke into the
atmosphere (Shastri 1977). Nitrogen and sulfur are the main source of foul smell in
the tannery industries. Decay of hides of animals starts immediately after its removal
from animal body before its proper curing (Kiernan 1985). Hides which have given
delayed curing may not smell bad in salted condition, but curing salt is removed
during soaking, and it increases chances of protein putrefaction and possibility of
bacterial growth (Mckinney 1969).
Chrome tanning or mineral tanning has an advantage of having no foul smell
generation unlike vegetable tanning which suffers from bad smell as tanning agent
comes from variety of plants and found in bark, twigs, nuts, and leaves which have
their own peculiar smell.
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N. Patel et al.
adversely affects the life of aquatic animals (Balasubramanian and Pugalenthi 2000),
(Song et al. 2000), (Mwinyihija et al. 2006).
Tanyard process viz. pickling, chrome tanning, leads to generation of acidic and
colored wastes. During vegetable tanning, waste consists of organic matter, whereas
high amounts of chromium are formed as waste in case of chrome tanning.
16.3.2 Solid Waste
As per European Commission, the amount of solid waste produced depends on
different type of factors, such as type of leather produced, technique applied, and
source of hides and skins (Basegio et al. 2002). Waste in solid form generated in
tannery can be divided into following forms:
– Non-proteinous waste.
– Non-collagenous protein waste.
– Tanned collagen.
– Untanned collagen.
On average, only 20% weight of hide is transformed into leather, and the
remaining goes as waste. Only 200 kg out of 1 ton of hides gets converted into
finished leather, whereas the remaining gets discharged as waste in form of waste
that contains blood, manure, protein, greases, and fat (Cooray 1999). A part of solid
waste or byproducts fixed consumers in the gelatin, textile, glue, and artificial leather
industry. Approximately, 35% of the original protein material comes out as effluent
tannery sludge, flashings, showings, and brimming. Only a small fraction of solid
waste produced in different tannery steps is utilized due to insufficient market
(Cheda et al. 1984).
16.3.3 Gaseous Waste
Tanneries are well known to discharge dust, odorous gases, and smoke into the
atmosphere (Shastri 1977). Nitrogen and sulfur are the main source of foul smell in
the tannery industries. Decay of hides of animals starts immediately after its removal
from animal body before its proper curing (Kiernan 1985). Hides which have given
delayed curing may not smell bad in salted condition, but curing salt is removed
during soaking, and it increases chances of protein putrefaction and possibility of
bacterial growth (Mckinney 1969).
Chrome tanning or mineral tanning has an advantage of having no foul smell
generation unlike vegetable tanning which suffers from bad smell as tanning agent
comes from variety of plants and found in bark, twigs, nuts, and leaves which have
their own peculiar smell.
584
N. Patel et al.