The tanning sector is known for the complexity and articulation of its production processes, which involve a series of chemical and mechanical treatments aimed at transforming raw leather into stable and durable leather. These processes, however, generate a significant amount of special waste and environmental impacts, which deserve special attention.
Characterization of the production cycles of the tanning sector
The tanning process can be divided into three main phases:
- Getting started:
- Greening: rehydration of preserved leathers.
- Calcination: removal of the hair and epidermis using solutions of hydrated lime and sodium sulphide.
- Fleshing: elimination of fabrics adhering to the skin.
- Splitting: Splitting the skin into layers.
- Decalcination: elimination of residual lime.
- Pickling: preparation for chrome tanning by treatment with formic and sulphuric acid.
- Tanning operations:
- Chrome tanning: Use of chromium salts to stabilize the leather.
- Tannin (Vegetable): Fixing vegetable tannin to stabilize leather, mainly for sole leather.
- Mixed tanning: Combines different methods.
- Shaving: Mechanical treatment to achieve the desired thickness.
- Finishing operations:
- Dyeing: Includes retanning, dyeing, fatliquoring and winding.
- Finishing and grinding: Further treatments to achieve the required characteristics.
Environmental impacts
The tanning industry is associated with numerous environmental impacts, mainly related to the production of wastewater, sludge and other waste. The inorganic and organic chemicals used during the process, such as chromium salts, hydrated lime, solvents and resins, contribute significantly to pollution.
Tanning effluents:
- Organic pollutants: They derive from the degradation of the skin and the organic products used.
- Inorganic pollutants: They come from the chemical additives used in the process.
- Salinity and COD: Significant problems related to the salinity and biodegradability of effluents.
Air emissions:
- Volatiles and particulates: The calcination, finishing and dyeing phases are critical.
- Hydrogen sulfide: Generated during calcination.
Types of waste produced
The tanning process produces various types of waste, including:
- Carnics and organic materials: Residues from the preliminary stages.
- Post-tanning waste and waste: Residues from mechanical operations.
- Wastewater and sludge: From purification treatments.
- Non-industrial solid waste: Offices, canteens, etc.
- Used oils and chemical residues: From maintenance and chemical processes.
- Hazardous waste: Such as exhausted degreasing baths and tanning liquids containing chromium.
Conclusions
The tanning sector has significant environmental impacts. It is essential to implement more sustainable technologies and practices to reduce pollution and manage waste more efficiently. In this context, continuous process improvement and the adoption of innovative solutions are essential to minimize the environmental impact of this industry.
Eurocorporation is the reliable partner for professional waste management and disposal.
