Tannery wastewater treatment.. Tannery wastewater is highly concentrated and contains contaminant particles of different size. This is due to a large variety of chemicals in leather industry: sulfuric acid, lime, soda ash, sodium sulfate, sodium sulfide, hypophosphite, ammonium sulfate, synthetic surfactants and finishing agents, kerosene, methyl esters, molasses etc. Synthetic surfactants are used in tanneries as solvents, wetting agents, detergents, emulsifiers, dispersants and accelerators of the processes.

During various operations associated with tanning and shaving hides in preparing leather, all these substances get into the wastewater and into the sewers. In addition, this wastewater contains components of skins, namely collagen proteins, fats and fat-like substances, some minerals containing sodium, potassium, calcium, and other elements. The specific amount of wastewater per 1,000 dm2 production is 2-9,5 m3 (lower values are characteristic for curing of hard skins, and higher are for chrome-tanned leather).

The conventional technologies for treatment of highly concentrated wastewater, particularly from tanneries, have several limitations. Therefore, it is appropriate to improve them using the vortex layer devices (AVS).

These devices were developed in the 1960s and became known as intensifiers of different processes, including tannery wastewater treatment.

In the chamber of the AVS various processes affect water purification:

• Intensive mixing and dispersion;
• Electrolysis;
• Impact of electromagnetic fields;
• High local pressure, etc.

Under other conditions these reactions last for minutes and hours, in the AVS they occurs within minutes, even seconds.The AVS used for wastewater treatment:

• Reduces the consumption of reagents;
• Reduces the production floor-space, allocated for a wastewater treatment plant;
• Speeds up the cleaning process;
• can be implemented into any technological process line.