Module 4



Students need to fully grasp the concepts covered in Module 1 in order to fully understand Module 4.

This module covers the clean technology that can be used by the tanner in the beamhouse and tanyard, the processes used, the chemistry or biochemistry of the clean technology processes, the function of the chemicals used in the processes, equipment modifications that may be necessary in order to use the clean technology processes, as well as the advantages and disadvantages of the clean technology processes.

The following are covered in this module:

Mass balance in leather processing

Salinity problem within tannery wastewaters

Carbon footprint

Processing of green hides

Salt-free curing methods

Mechanical de-salting

Environment-friendly degreasers (NPE-free)

Recycling of soak floats

Hair-save unhairing

Utilisation of hair from the hair-save unhairing process

Recycling of lime liquors

Low-sulphide unhairing

Sulphide-free unhairing

Oxidizing unhairing

Enzyme use in the beamhouse

Use of biochemicals in the beamhouse

Organic acid deliming

Carbon dioxide deliming

Aqueous degreasing / lipase enzymes

Thrublu process

Salt-free pickling

Recycling of pickle liquors

Chrome liquor recycling / recovery

High-uptake chrome tanning

Two stage chrome tanning process

High-end pH basification

Hybrid chrome tannage


Sources of COD in tannery effluents

In order to fully understand the above processes, students need to understand the concepts such as COD, BOD, conductivity, total solids, TDS, SS, TKN, sulphide, chlorides, FOG, shrinkage temperature, chromium concentration in the effluent etc