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P. S. Kumar et al.
• Physical separation of fats
• Easy sedimentation of suspended solids in primary settling tanks by using
coagulants and flocculants
During this step, chrome and sulfides are precipitated from tanyard chrome and
beam house; In order to deal with the hydrogen sulfide produced, oxidation using a
metal catalyst is possible and must be operated separately to avoid.
Secondary treatment.
This step is an anaerobic biological treatment to reduce the biological oxygen demand
(BOD). The treatment is suitable for the reduction of sludge at lower costs and is
extensively used in industries. However, the toxicity and corrosive properties of
anaerobic are the drawbacks faced by many tanneries that have not been adopted.
Tertiary treatment.
This step consists in using sand filter beds and clarifiers to separate the liquid effluent
from the solids and dewatering the sludge. Even though the drying process of sludge
is more recommended, the liquid effluent produced is unfortunately released to the
environment.
8 Toxicity of Some Chemicals Used During Leather
Processing
During the manufacturing process of the leather, an extensive range of chemicals are
used. Among the bunch of chemicals, one can cite.
• Phtalates such as benzyl butyl phthalate (BBP), di-ethyl hexyl phthalate (DEHP),
and dibutyl phthalate (DBP) are employed as plasticizers in microporous artificial
• Biocides: Used during the finishing process of microbiological water-based
chemicals. The combination of biocides such as chlorisothiazolinone (CIT) and
methyl-isothiazoline (MIT) can be used as irritant [13]
• Formaldehyde: It acts as a cross-linker and helps for the manufacture of diverse
type of leathers
• Inorganic pigments: Their properties including brilliant color and fastness is
required especially for chromate and lead, although considered as toxic species
[12]
• Organotin compounds: Used in the finishing process like dibutyl tin
• M-Methyl pyrrolidone acts as a wetting agent, swelling material, and plasticizer
to improve the performance of leather
It is noted that a bunch number of chemicals used during the tanning processing,
which after discharged into the environment will be harmful to human health and
plants.
P. S. Kumar et al.
• Physical separation of fats
• Easy sedimentation of suspended solids in primary settling tanks by using
coagulants and flocculants
During this step, chrome and sulfides are precipitated from tanyard chrome and
beam house; In order to deal with the hydrogen sulfide produced, oxidation using a
metal catalyst is possible and must be operated separately to avoid.
Secondary treatment.
This step is an anaerobic biological treatment to reduce the biological oxygen demand
(BOD). The treatment is suitable for the reduction of sludge at lower costs and is
extensively used in industries. However, the toxicity and corrosive properties of
anaerobic are the drawbacks faced by many tanneries that have not been adopted.
Tertiary treatment.
This step consists in using sand filter beds and clarifiers to separate the liquid effluent
from the solids and dewatering the sludge. Even though the drying process of sludge
is more recommended, the liquid effluent produced is unfortunately released to the
environment.
8 Toxicity of Some Chemicals Used During Leather
Processing
During the manufacturing process of the leather, an extensive range of chemicals are
used. Among the bunch of chemicals, one can cite.
• Phtalates such as benzyl butyl phthalate (BBP), di-ethyl hexyl phthalate (DEHP),
and dibutyl phthalate (DBP) are employed as plasticizers in microporous artificial
• Biocides: Used during the finishing process of microbiological water-based
chemicals. The combination of biocides such as chlorisothiazolinone (CIT) and
methyl-isothiazoline (MIT) can be used as irritant [13]
• Formaldehyde: It acts as a cross-linker and helps for the manufacture of diverse
type of leathers
• Inorganic pigments: Their properties including brilliant color and fastness is
required especially for chromate and lead, although considered as toxic species
[12]
• Organotin compounds: Used in the finishing process like dibutyl tin
• M-Methyl pyrrolidone acts as a wetting agent, swelling material, and plasticizer
to improve the performance of leather
It is noted that a bunch number of chemicals used during the tanning processing,
which after discharged into the environment will be harmful to human health and
plants.