5. Conclusions
The present investigation is a breakthrough approach in making
the beam house operations of the leather chemical free. It was a
successful attempt to modify the conventional chemical process to
a lime free, environmentally benign technology. The productions of
enzymes were successfully scaled-up in 300 L stirred reactor
resulting in a maximum yield of 4568 U/mL in 18 h for protease and
34.91 IU/mL of lipase in 36 h. Hundred percent efficient enzymatic
dehairing and degreasing of skins and hides were achieved at pH
value of 8.0 and temperature 30e37
C with the enzyme concentration
of 2e5% (w/v) of protease (B. licheniformis) for dehairing and
5e10% (w/v) of lipase (B. subtilis) for degreasing within 8e12 h of
incubation. Enzymatic leather processing also significantly decreases
the processing time, BOD, COD, water and chemical consumption
during the operation. The bulk size tannery trials at CLRI,
Chennai were efficient and successful leading a way for changing
the beam house operation from chemical to enzyme assisted and
now finally to total enzyme based leather processing. This all forms
a part of making the tannery go green.