To prevent oil spill from sipping into the public sewage system, companies like washing halls and workshops are required to have an approved oil separator. When wastewater containing oil is flushed down the drain, it must flow into an oil separation facility. The oil separator prevents the oil from reaching the public sewage systems or the watercourses.

Oil separators are used to treat water that is polluted with small amounts of oil. Operations that have an oil separator, for example washing halls or workshops, hold the responsibility to make sure that oil, sludge and sand is collected, emptied and delivered to an approved waste site.

Size of the separator
The oil separator must be proportionate to the amounts of water it is bound to receive. Furthermore, it is important that the water stays long enough in the oil separator. This is to allow the oil to float up to the surface. If the water amount coming into the separator exceeds the oil separator’s capacity, the cleaning effect will be reduced considerably.

Emptying the oil separator
Oil separators need regular supervision, and should be emptied when a maximum of 80 percent of the collection capacity is reached. The oil separator should still be emptied at least once a year. These are recommendations given by the Environment Agency, and that we in Norva24 think are important to follow up on.

Oil separators that have storage of accumulated oil in the wet volume, should be emptied before 25 percent of the volume is filled with oil. If this is not done, the cleaning effect will be reduced considerably. Sand traps should be emptied when approximately 50 percent of the volume is full. The rule about yearly emptying applies also in this case.

Avoid chemicals
It is important to use chemicals that do not reduce the functionality of the oil separator.

When oil is separated as drops in water, it is called an oil emulsion. Use of chemicals may lead to such emulsions. Oil emulsions mean that the oil does not float to the surface, and this reduces the functionality of the oil separator.

If you are a business that require the use of an oil separator, you must avoid using products or chemicals that lead to the formation of stable oil emulsions. An oil separator is not made to clean anything but wastewater containing oil. Chemical products like degreasers, brake fluid, lacquer and solvents must therefore not be poured into the oil separator. Such chemical products must be sorted at the source and submitted as hazardous waste.

Handling of oil, sand and sludge
The oil separated by an oil separator is hazardous waste. The same goes for waste from the associated sand trap. Oil and sludge must be submitted to an approved site for hazardous waste. It is important that oil and sludge is not mixed with other waste. It is also important to remember that waste from oil separator and sand trap may not be stored at the business for more than one year.

Businesses that have an oil separator must be able to document that they have sufficient routines for emptying, operation and maintenance of the separator. This is something we at Norva24 can help you with. We can contribute to routines that secure and maintain the functionality of the oil separator, and that there is no danger of contamination.

Test taking
There are also specific requirements for test taking of outlet water from oil separators. The oil content in outgoing water must be lower than 50 mg per litre of water, according to Chapter 15 of the Pollution Regulations.

The tests must be sent to an accredited laboratory for analysis, regardless of emptying, and such tests must be submitted at least once a year. Some municipalities have their own regulations that may differ from and be stricter than national requirements. An example is the municipality of Ullensaker, which hosts the country’s main airport.

The municipality is the authority for operations included in Chapter 15 of the Pollution Regulations, “Requirements for emissions of wastewater containing oil”. The municipality may also set requirements for wastewater containing oil from operations that discharge to the municipal pipe system.

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