The splat on the mat

Oil spots on filling station forecourts can not only spoil the interior of your car as you tread a dollop of black gold into the footwell but are a serious environmental concern as rainwater and carwash ultimately sees the oil residue washed into the drainage system and thence the environment. Now, researchers from Perm have developed a refining unit for cleaning rainwater sewage from filling stations.

The research team led by Mikhail Kovalev, Perm State Technical University, has successfully tested their product in Moscow and Perm. There are already forty stations in the two cities utilising the clean-up system.

The product is based on a new filter material, "Kombi", which is composed of a fibrous carbon sorbent, formed by coagulating chemical cellulose fibres. The filtering process involves three steps: settling, refinement through the mechanical filter and a two-stage additional sorption refinement. Rainwater enters a huge settling vat to allow large insoluble particles, such as mud, to settle on the bottom. The settled water is then refined through a mechanical filter, a metal net to remove smaller particles.

The two-stage refinement then passes the water twice through the Kombi filters to extract oil-product residues. At this point, say the devices developers, the water is 1500 times clearer.