Metallic ions zap water-based algae

A faint smell of rotten eggs greets factory staff as they start up the machines ready for the Monday morning shift. The sulphur is released by bacteria as they feed on hydrogen sulphide in the stagnant, oxygen-free environment of tanks of cutting oils and coolants. The cost to industry of dealing with these contaminated fluids […]

A faint smell of rotten eggs greets factory staff as they start up the machines ready for the Monday morning shift.

The sulphur is released by bacteria as they feed on hydrogen sulphide in the stagnant, oxygen-free environment of tanks of cutting oils and coolants.

The cost to industry of dealing with these contaminated fluids is huge. Bacteria affects the way the cutting tool works, impairing the quality of the machined part. Special arrangements have to be made for the disposal of spent cutting fluids. And skin disease is a scourge.

The problem most affects factories using water-based emulsions, which are cheaper than more bacteria-resistant synthetic varieties.

Major Randolph Reid, a former army doctor and expert in preventive medicine and environmental health, believes he has a solution.

Reid, now technical director of Environmental Health and Pollution Control of Camberley, invented a process that keeps bacteria and algae at bay from water-based systems. His company’s Random Metering System is used in hospitals, swimming pools and sewage plants.

The method could be applied to bacterial growth in factories’ cutting oils and coolants, he believes.

The way it works is simple but effective. ‘We castrate the bacteria and stop them from multiplying,’ he says.

The process puts metallic ions into pure water. The ionised water becomes a dosing source and is then injected into whatever water-based fluid needs treatment. This happens at a controlled rate, which can vary from five to 35,000 litres per hour. If the dosing levels are right, the ions will kill the bacteria or prevent them from multiplying.

Keeping potentially unstable ions stable is the key to the success of the RMS method, says Reid.

A catalyst, which acts as a non-sacrificial anode, contains the secret which took him eight years to develop and which, people say, defies the laws of physical chemistry. But Reid refuses to expand further.

Silver, one of the metals which can be used as the process electrode, forms unstable ions with a useful life of only four hours. Using RMS, that time can be extended to around four months, with a saving on electricity bills.

That is because ions are generated on demand by a low-voltage current passed through the purified water.

But RMS does not solve the cutting fluid problem altogether. Contaminants such as swarf and dirt must be removed by usual methods. And in time the cutting fluid will need replacing with a new batch.