Waste water standards
The disposal of waste water from vehicle washing must be considered when creating a vehicle washing platform. Depending on the type of waste and the type of water connection the obligations may vary. These obligations must therefore be taken into account from the start.
Disposal in natural environment or in rain water networks
Direct disposal of water into the natural environment is prohibited by the water laws of 1992 and the technical measures applicable to vehicle washing centres are determined by the departmental sanitary regulations governed by the French DDT department (Territories Division).
A system of de-oiling and de-soiling of waste water must therefore be installed with a maximum hydrocarbon content of 5 mg/L.
Disposal in mains drainage network
The connection of a vehicle washing centre to a public drainage network is possible if a connection convention is validated by the water company.
In this document, the mayor of the commune concerned sets the conditions for the authorisation for this connection. The de-soiling and de-oiling systems are necessary for waste water, however for hydrocarbons the content must be below 5 mg/L.
A minimum provision must be made for:
- limiting the muddy/soil wastes (Decantation– De-soiling)
- retaining hydrocarbons and oils (De-oiling)
Decantation and de-soiling
The waste water from a vehicle washing station is disposed of into the decantation system where the solid matter settles at the bottom. The decanter is also used to settle the effluent before it enters the separator.
Separation of hydrocarbons and oils
Light liquids such as fuels, mineral oils, solvents and detergents form a layer on the surface of the water in the hydrocarbon separator.
This device must also be equipped with a ballcock to close the waste water drainage pipe when the separator tank is full of oil or when it produces an accidental discharge of a large quantity of hydrocarbon type liquid.
For disposal of waste into the natural environment, an extractible coalescent absorbent cartridge must be integrated into the system in order to respect waste disposal standards.
The water produced from these systems can then be rejected into the sewerage system or into the natural environment unlike waste water. The manhole cover, located after the device, is designed to be able to take water samples and to control the residual hydrocarbon content.
The installation of a powerful water recycling system limits the volume of waste by re-using much of the recycled washing water.