Water Footprint in Leather Tanning and Steel Production
143
and indirect water usage by consumption or manufacture of leather and reduce the
consumption of water.
6 Pollution Derived from Tanning Process of Leather
It is well known the economic impact of leather industry on the development of a
locality, and extended to a country. Nonetheless, the different activities that generated
solid waste and wastewater effluent consisted of biocides, synthetic tannins, detergents, and resins [6, 11]. As previously presented in the different tanning process,
the leather industry uses a huge amount of water and the processing generated pollutants to the environment. During the different stages of leather tanning processing
including soaking, unhairing/liming, deliming and bating, chrome tanning, posttanning, and finishing, the polluting load from produced wastewater consist of
sulfates, chlorides, Chromium, sulfides, suspended solids, etc., at various ratios.
It has been noticed from previous studies the high impact (nearly 90%) of pretanning and tanning on the overall pollution from tannery [5]. As far as concerned the
pretanning process, the enhancement of chemical species such as chlorides, sulfates,
total dissolved solids (TDS), chemical oxygen (COD) in tannery wastewater are
mainly due to the fluctuation of pH. The parameters including biochemical oxygen
demand (BOD), COD, and suspended solid result in the dehairing process by using
sulfide and lime. Moreover, the negative effects of sodium sulfide due to its strong
alkaline properties as found to be harmful both to the environment and plants. The
use of chromium during chrome tanning especially generates the shortcomings of
the ecological system. Finally, the waterbodies may be altered by the exceedingly
discharge chemicals from polluted sediments.
7 Wastewater Treatment Processes in the Leather Tanning
Industry
In the leather industry, the wastewater treatment systems consist of four main steps
including pretreatment or preliminary treatment, primary, secondary, and tertiary
treatment.
Pretreatment.
Mechanical screens, distribution wells, grit removal apparatus, and equalization tanks
are used in this step in other to separate suspended solids from raw waste and to
remove solid material (hair, coarse, sand, grit, and grease).
Primary treatment.
Two different processes are considered in this step including the following:
143
and indirect water usage by consumption or manufacture of leather and reduce the
consumption of water.
6 Pollution Derived from Tanning Process of Leather
It is well known the economic impact of leather industry on the development of a
locality, and extended to a country. Nonetheless, the different activities that generated
solid waste and wastewater effluent consisted of biocides, synthetic tannins, detergents, and resins [6, 11]. As previously presented in the different tanning process,
the leather industry uses a huge amount of water and the processing generated pollutants to the environment. During the different stages of leather tanning processing
including soaking, unhairing/liming, deliming and bating, chrome tanning, posttanning, and finishing, the polluting load from produced wastewater consist of
sulfates, chlorides, Chromium, sulfides, suspended solids, etc., at various ratios.
It has been noticed from previous studies the high impact (nearly 90%) of pretanning and tanning on the overall pollution from tannery [5]. As far as concerned the
pretanning process, the enhancement of chemical species such as chlorides, sulfates,
total dissolved solids (TDS), chemical oxygen (COD) in tannery wastewater are
mainly due to the fluctuation of pH. The parameters including biochemical oxygen
demand (BOD), COD, and suspended solid result in the dehairing process by using
sulfide and lime. Moreover, the negative effects of sodium sulfide due to its strong
alkaline properties as found to be harmful both to the environment and plants. The
use of chromium during chrome tanning especially generates the shortcomings of
the ecological system. Finally, the waterbodies may be altered by the exceedingly
discharge chemicals from polluted sediments.
7 Wastewater Treatment Processes in the Leather Tanning
Industry
In the leather industry, the wastewater treatment systems consist of four main steps
including pretreatment or preliminary treatment, primary, secondary, and tertiary
treatment.
Pretreatment.
Mechanical screens, distribution wells, grit removal apparatus, and equalization tanks
are used in this step in other to separate suspended solids from raw waste and to
remove solid material (hair, coarse, sand, grit, and grease).
Primary treatment.
Two different processes are considered in this step including the following: