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Nutshell filters

The NutArt® nutshell filters represent an efficient solution for oily water polishing treatment with a high removal efficiency for suspended solids (TSS) and free oils. The filtration phase alternates with an efficient cleaning system that happens periodically to restore filter activity. The cleaning, based on a circulation pump and an external scrubbing device, is simple, does not include chemicals or air scouring, and allows media recovery.

Key features


up to 98% removal of TSS (above 5 micron) and filterable free oil

High flux rate allowed

reducing filters dimensions

Media refilling

less than 5% per year

Continuous feed

including during the backwashing phase


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Very efficient and easy automatic cleaning system with no chemicals or air scouring required for the cleaning of the filters

High flux rate design for a reduced footprint

Removes 98% of all filterable contaminants

Cleaning with feeding water (no service water required)

Continuous feed allowed even during cleaning with no interruption of feed water

Easy maintenance activity (external scrubber installation enables operators to avoid vessel entry for screening maintenance and removable type screening for the scrubber)

Dedicated backwashing pump


Nutshell filters are typically adopted as a polishing treatment for oily water. Solids and free oils are both physically absorbed thanks to their affinity with nutshell media and the coalescing properties of the nutshell media surface.

During the filtration phase, dirty water enters from the top of the filter and is forced down through the media, where suspended solids and oils are retained. Treated water exits from the bottom of the vessel, and the filtration step ends by the elapsed time or because of a high differential pressure signal across the filter.

When the filtration phase is finished, the media backwashing phase begins, aimed at the removal of the accumulated contaminants. The media from the vessel is sent through the scouring pump to an external scrubber vessel, where the media is cleaned and separated from contaminants.

The scrubber retains the media while contaminants flow out with backwashing water, thus reducing the total required water quantity.

Have a look at how vital NutArt® nutshell filters could be in Produced Water Treatment.