Coolant deterioration
During the metal working process, the heat of operation and the chemical reactivity of swarf fines initiates degradation of metal working fluid. The particles chemically interact with the oils in the emulsions weakening the emulsion and breaking the fluids down in its separated constituents.

Swarf also facilitates the growth of the bacteria and fungi that feed on the coolant by providing a substrate for them to grow on. Bacteria use the emulsion additives and oil for food and similarly contribute to coolant degradation. This is called coolant spoilage. Coolant degradation results in a reduction of the ability of the coolant to lubricate and transfer heat away from the metal working process.

Microbial activity
Bacteria and other microbial organisms thrive in the environment created by the impurities in the coolant. They feed upon mineral oils, fatty acids, emulsifiers, corrosion inhibitors, other additives and waxes in oil based and synthetic coolants.

Anaerobic bacteria grow in environment lacking oxygen. They feed upon the coolant and produce noxious byproducts such as hydrogen sulfide. This is commonly referred as the Monday morning odor.

Problems associated with microbial spoilage
Microbial actin directly affects the coolant resulting in the splitting of emulsions, decreased pH, increased corrosion, degradation of the ingredients in the coolant and loss of lubricating ability within the coolant itself. Odors may develop including hydrogen sulfide as a product of the bacteria metabolism. Bacteria may also expose workers to pathogens and contribute to respiratory irritation and skin irritation, like dermatitis. Workpiece quality decreases, resulting in increased surface blemished tool life, and increased down time to treat for bacteria and repair the equipment. The bacteria may also cause increased foaming and oil separation in the system and cause clogged lines ,filters and valves.

Extending the life of coolants
Swarf and tramp oil should be removed in process. Chemicals are available that can be added to the coolant to protect emulsions from reactive metal fines and extend the life of the coolant. The presence of swarf and tramp oil create a habitat that promotes the growth of the bacteria. Anaerobic bacteria and fungi eat the organic components of the oil and/or emulsions reducing the effectiveness of the coolant. Therefore, bacteria and fungi should be removed from the coolant or prevented from growing in the coolant.

There are several methods for removing residual oil from metalworking fluids or coolants. For example several filtration techniques are known, screen type filters, and the like, for removing the suspended oil particle contaminants, several coalescing techniques are also known in which a porous media is used to enhance oil droplets growth and gravity separation.

However, these filtration and coalescing methods suffer from several disadvantages including the requirement of backwashing and/or frequent removal and replacement or cleaning of coalescing or filtration media which lead to down times and high maintenance costs that are also associated with the use of centrifuges.

Liquid-Liquid Separation

WaterWall® - Complete separation of non-miscible liquids at high flow rate.

Solid-Liquid Separation

Techno-Floc®: Purification process of polar liquid wastes containing colloidal dispersion of solvated particles.

Waste Heat Recovery

TTVM/G® (Torini Thermo-Volumetric Motor/Generator): A waste heat recovery type generator which offers the ability to convert waste heat into electric energy. 
» Go to TTVM/G Website