16.5.2 Primary Treatment
Primary treatment is associated with physico-chemical processes where sedimentation and skimming are used for the removal of settleable organic and inorganic
solids. Moreover, the extra advantage of this method includes satisfaction of
25–50% of BOD 5 , 65% of oil and grease, and 50–70% of total suspended solids
(TSS). The sludge generated from primary sedimentation is known as primary
effluent or sludge.
16.5.3 Secondary Treatment
Secondary treatment is related with the biological treatment of the waste, which is
carried out in the presence or absence of oxygen by aerobic and anaerobic microorganisms, respectively, or in some cases by facultative microorganisms.
16.5.4 Tertiary Treatment
Tertiary method is employed for the removal of waste constituents that cannot be
removed by using primary and secondary treatment methods. This method gets
associated with the advanced treatment methods for reduction of residual COD.
Choice of treatment method depends upon a number of factors, such as location
of plant in respect to neighboring use of land; if a number of tanneries exist together
then cooperative treatment will prove to be more economical as compared with the
individual tannery waste treatment. It also depends on the final tannery and discharge
standard specified by the law (Dixit et al. 2015).
16.6 Tannery Waste Management Process
After discussing all the harmful impact of tannery industry on the environment, it is
the need at present hour to work together in order to find a suitable solution that will
help to satisfy our needs of leather and causing minimal/zero effect on the environment. For this, we have to adopt following waste management practices.
16 Environmental Impact and Treatment of Tannery Waste
589
Primary treatment is associated with physico-chemical processes where sedimentation and skimming are used for the removal of settleable organic and inorganic
solids. Moreover, the extra advantage of this method includes satisfaction of
25–50% of BOD 5 , 65% of oil and grease, and 50–70% of total suspended solids
(TSS). The sludge generated from primary sedimentation is known as primary
effluent or sludge.
16.5.3 Secondary Treatment
Secondary treatment is related with the biological treatment of the waste, which is
carried out in the presence or absence of oxygen by aerobic and anaerobic microorganisms, respectively, or in some cases by facultative microorganisms.
16.5.4 Tertiary Treatment
Tertiary method is employed for the removal of waste constituents that cannot be
removed by using primary and secondary treatment methods. This method gets
associated with the advanced treatment methods for reduction of residual COD.
Choice of treatment method depends upon a number of factors, such as location
of plant in respect to neighboring use of land; if a number of tanneries exist together
then cooperative treatment will prove to be more economical as compared with the
individual tannery waste treatment. It also depends on the final tannery and discharge
standard specified by the law (Dixit et al. 2015).
16.6 Tannery Waste Management Process
After discussing all the harmful impact of tannery industry on the environment, it is
the need at present hour to work together in order to find a suitable solution that will
help to satisfy our needs of leather and causing minimal/zero effect on the environment. For this, we have to adopt following waste management practices.
16 Environmental Impact and Treatment of Tannery Waste
589