Background

Metalworking fluids (MWF) are used in industry world-wide to cool and lubricate metal parts during metalworking operations such as cutting, grinding, honing and forming. By far the major user industry is transport, comprised of automotive, trucking, aerospace and components manufacture. Spent metalworking fluids are considered oily wastewater and contain a mixture of free and emulsified oils together with a cocktail of toxic water-soluble compounds including biocides (which control unwanted bacterial growth in the operational fluids), and it is generally not possible to release such compounds straight to sewer. Rather, they must be treated first to reduce the pollution load.

Untreated metal working fluid (left) and metal working fluid after treatment with Microcycle (right)

The principal measure of the pollution load of spent MWF is its Chemical Oxygen Demand (COD), measured in milligrams per litre. The COD is the amount of oxygen consumed to completely chemically oxidise the organic water constituents to inorganic end products. If high COD liquid waste is released into rivers, it can be used as food by algae, which can then proliferate and deplete the dissolved oxygen, killing the higher river fauna, particularly fish. Waste MWFs carry too high a COD for them to be disposed of to the local sewers. Most of this waste is taken away to centralised treatment and disposal facilities. Some of the largest waste producers have on-site treatment systems such as vacuum-evaporation or ultra-filtration. However, these treatments are only partially effective at removing the pollution load and they also leave a residual toxic sludge which has to be disposed of.

Bench scale bioreactors containing Microcycle and exhausted metal working fluids, in the the Microbial laboratories, Oxford

Regulatory requirements for treatment and disposal of MWF have become ever more stringent. The major legislative initiatives affecting MWF disposal are the Hazardous Waste Regulations and Landfill Directive. Under the new Landfill Directive liquids may no longer be disposed of to landfill, and this previously common low-cost option for the disposal of MWFs is now closed. Furthermore, all oily wastes are now classified as hazardous, and may only be consigned to registered hazardous waste landfill sites.

Further impacts of legislation include the requirements that:

  • all wastes must be properly segregated (which prevents, for example, the mixing of hazardous and non-hazardous wastes, and also mixing of MWF filter cloths and MWF, for example)
  • all wastes must be assessed prior to landfill to ensure that weight and hazardous content are reduced where possible
  • all hazardous waste producers must register with Environment Agency
  • the duty of care upon waste producers extends to the point at which the waste has either been disposed of or fully recovered, and waste taken off-site must be accompanied by an accurate description of the waste and a transfer note, and must use licensed waste managers.

The result of these regulatory initiatives over the last few years has been to inflate the price of MWF disposal. This trend will continue for some time as the new environmental and chemicals regulations are adopted in full. This is where Microbial Solutions and Microcyle come in: a more environmentally friendly technology and a LOWER COST CERTAINTY combined with an onsite no-tankering-away solution.