Use of Enzyme in Paper & Pulp and Leather Industries

“Enzymes in pulp & Paper Industries”

Ø  The pulp & papers industry process huge quantities of lignocellulogic biomass every year.

Ø  The technology for pulp manufacture is highly diverse; and application of microbial enzyme has taken the opportunity to take those.

Ø  Long age enzyme used in the paper industries only for the modification of raw starch.

Ø  After 1980s enzyme in the pulp & paper industries increase rapidly.

v  Prebleaching of pulp is the most important application of enzyme in the present years..

4  Xylanase- is the most effective enzyme for prebleaching in P & P industries. Xylanase prebleaching technology is used worldwide.

4  Lipase- in large scale paper making processes as a routine operation from 1990s.

4  Enzymatic deinking applied during mill trial for recycle of paper.

4  Pilot scale- University of Georgia.

“Enzymes in leather processing Industries”

4  Processing steps of leather

1.      Soaking

2.      Unhairing/dehairing   

3.      Degreasing

4.      Bating

5.      Tanning

4  Soaking

®    First important operation of leather processing.

®    Hides & skins received into tannery are in the four conditions.

(i)                 fresh or screen

(ii)               As wet salted

(iii)             Dry salted

(iv)             As dry

®    To obtain best quality of leather for all categories of skins & hides soaking is applied and is works quite good.

®    Hides & skins are cleaned perfectly by removing the following components dirt, blood, flesh, grease, dung etc.

®    Rehydrate the skin to bring back to state of green hide.

®    Soaking agents are                             -    Chemical agents

-       Surface active agents

-       Enzymatic agents.

®    At the time of soaking specific enzymatic agents such as protease and lipase are used as a biocatalyst.

®    These enzymes enhance water uptake by dissolving intrafibrillary proteins that cement fibers together.

®    Disperse fats oils together with dirt & other contaminants present on skin.

4  Unhairing

®    Remove hair from hide.

®    Conventional oral way-

®    Use of lime & sodium sulphide - hair burning.

®    Enzyme assisted unhearing results in a grain surface & unproved area yield & softness.

®    Specific protease enzyme replaces the use of lime, sulphides & amines.

®    The hair burning process is the environment friendly and it is used worldwide and for hair saving process it is considered as better alternative.

®    In this case hair is not dissolved but can be filtered out from the float.

®    In case of waste discharges COD and BOD can be possible to reduce up to 50% and 30% respectively.

4  Degreasing

®    Lipase specially degrades fat cannot damage the leather.

®     Lipase hydrolysis not only fat on the outside of the hides & skins but also the fat inside the skin structure.

®    By degreasing method most of the natural fat has been removed and result in the effect on tanning, re tanning & dyeing that have eventually have a better effect.

®    The main advantage of using lipases is a more uniform color & a cleaner appearance.

®    Lipase present a more environmentally sound method of removing fat.

®    Lipase also improves the production of hydrophobic leather (water proof).

®    For bovine hide, lipase replaces the fat completely.

®    Lipase and surfactants are used as good detergents because it can work better than sheep skin which contains 40% fat and use as commercial solvent is very common. One of the disadvantages of this sheep skin when we use it as a solvents have tend to dry out the skin & give it a pale color.

4  Tanning

®    Tanning is a process of treating skin of an animal to produce leather which is more durable & susceptible to decomposition.

®    Acid protease  : Aspergillum fumigates,

Alkaline     : Bacillus subtilis B licheniformis

®     Tanning permanently altered the protein structure of skin.

4  Bating

®    To make leather pliable, the hides & skins required an enzymatic treatment before tanning known as bathing.

®    During bating unwanted protein are removed and scud is loosened.

®    Bating de-swells swollen portion & prepare leather for tanning.

®    It makes the grain surface of the finished leather clean, smooth & fine.

®    For leather processing bathing with enzyme is used as an indispensable operation to get best quality of leather that cannot possible to get by using other methods.