W100 · Stage 3 of 4

W100 Activated Carbon Filter

The polishing stage — a full-depth bed of coconut-shell activated carbon that adsorbs the odour, colour, surfactant residue and dissolved hydrocarbons no filter bed can strain out. Capacities from 8.8 to 440 US gallons per minute.

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KKE W100 activated carbon filter installed on its skid frame — FRP vessels with multiport valves, PVC plumbing and pressure gauge, storage tanks behind

Free tool

Size your water-recycling system in minutes

Tell us what you wash and the tool returns your treatment capacity, the exact W100 skids you need, tank volumes and the freshwater you'll save — with the annual saving in your local currency.

Open the sizing tool

90%

less freshwater

2 min

to a full estimate

Why a wash bay needs it

What sand cannot take out, carbon can

Stages 1 and 2 deal in things you can see: free oil, sludge, suspended solids, turbidity. What they leave behind is dissolved — shampoo and degreaser surfactants carried over from the last wash, the organics that go sour in a warm recycle tank, the last of the hydrocarbon, and chlorine from your make-up water. None of it is a particle, so no filter bed can strain it out. Carbon is the stage that removes it.

What the customer notices

Smell and foam lose you the wash

These are the two complaints that come back from recycled water, and both are dissolved organics.

Organics in a warm recycle tank turn anaerobic and the water goes sour — customers smell it the moment the bay opens
Carried-over shampoo and degreaser surfactants foam in the tanks and in the bay
A grey-brown tint that makes water you have just cleaned look dirty

The finish

Dissolved residue dries on the panel

Anything still in solution when the water hits the vehicle is left behind when it dries.

Surfactant and organic residue dries as streaks and film, worst on glass and dark paint
Residual dissolved hydrocarbon put back onto a surface you have just degreased
No amount of extra sand filtration helps — none of this is a suspended particle

Downstream and compliance

It protects Stage 4 and your discharge numbers

Carbon earns its place twice: once on the water you reuse, once on the water you let go.

Dechlorinates the make-up water, and chlorine is what oxidises and shortens softening-resin life
Dissolved organics foul ion-exchange resin the same way — filtering them out first is what makes Stage 4 last
COD, oil and grease, and odour are normally written into a discharge consent; carbon is what brings those numbers down

Labelled cutaway of the KKE W100 activated carbon filter: multiport control valve, upper distributor, freeboard, and a full-depth granular activated carbon bed above the bottom laterals, with no sand or gravel layers — One media, full depth — granular activated carbon from the laterals to the freeboard, with no sand or gravel layers taking up vessel volume. Service flow runs down through the bed; the slotted laterals collect it and the central riser returns it to the valve outlet.

Cutaway of the KKE W100 activated carbon filter showing the full-depth granular activated carbon bed, central riser tube and bottom laterals inside the FRP vessel

How it works

Adsorption, not filtration

A sand bed works by geometry: a particle is either too big to pass or it is not. Carbon works by chemistry of surfaces. Steam activation riddles every grain with a network of pores so fine that a single gram carries something in the order of a thousand square metres of internal surface — and dissolved molecules passing through stick to those pore walls and stay there.

That is adsorption: molecules accumulating on a surface. Absorption, which the two are constantly confused for, would mean soaking into the material itself. Nothing here is soaked up and nothing is chemically consumed.

Coconut-shell carbon — its pores sit mostly in the micropore range, which is exactly the size band that suits the small dissolved molecules in wash water: surfactants, odour compounds, chlorine.
Harder than coal-based carbon — it survives repeated backwashing with fewer fines, and it comes from an agricultural by-product rather than mined coal.
Contact time is the design variable — not a micron rating. The bed has to hold the water long enough for molecules to find a pore, which is why the vessel is sized to your flow.
Run it above its rated flow and it does not half-work — contact time falls and molecules pass straight through an otherwise perfectly good bed.

How it works

The service cycle

A single downward pass, in-line after the multimedia filter. Stage 3 carries no pump of its own — it runs on the pressure Stage 2 delivers, which is what makes it straightforward to add to a line already running.

In on Stage 2's pressure

Filtered water from the multimedia filter enters through the multiport control valve and drops into the upper distributor. The diffuser basket spreads it across the full area of the bed so the incoming stream cannot cut a channel down through the carbon and bypass most of it.

Down through a full-depth carbon bed

There are no sand or gravel layers in this vessel. Every millimetre from the laterals to the freeboard is working carbon, which puts the maximum possible contact time into a given footprint — the one thing carbon performance actually depends on.

Molecules stick to the pore walls

As water travels down, dissolved organics, odour compounds, residual hydrocarbons and chlorine are drawn onto the internal surface of the grains and held there. The water leaving is clear, low-odour and free of the surfactant residue that foams and streaks.

Collected and returned

The slotted bottom laterals collect the polished water and send it up the central riser tube to the valve outlet — on to the resin softener if hardness is an issue on your site, or straight back to the wash.

Carbon fills up — it does not clog

This is the one operating difference worth understanding. A sand bed blocks: dirt accumulates, the pressure drop across it climbs, and the gauge tells you to backwash. A carbon bed does not block — it saturates. The top of the bed loads first and the working band migrates slowly downwards, while the water leaving stays just as good as it was on day one.

Then it stops being as good. When the working band reaches the laterals, odour and taste begin to break through — and they break through before anything moves on a pressure gauge. So on Stage 3, smell is the instrument. A rising odour in the recycled water is the signal that the media is spent, not a reading on the manifold.

Backwashing still matters, but it does a different job here: it lifts out fines, breaks up any channelling and re-loosens the bed. It does not regenerate the carbon — whatever has been adsorbed stays adsorbed. When the bed is exhausted the media is replaced, and spent carbon can be sent for thermal reactivation rather than landfilled. Budget for carbon by organic load, not by running hours.

At a glance

Key features

Adsorption, not absorption

Dissolved organics and odour molecules are held on the carbon's internal pore surface — around a thousand square metres of it per gram.

Removes odour, colour & foam

Polishes out the smells, tints, surfactant residue and residual hydrocarbons that no filter bed can strain out.

Coconut-shell carbon

Micropore-dominated and harder than coal-based carbon: right pore size for wash water, fewer fines through backwashing.

Full-depth carbon bed

No sand or gravel taking up vessel volume — maximum contact time in a given footprint.

No pump of its own

Connects in-line and runs on the pressure the multimedia filter delivers, so it drops into a running line.

FRP pressure vessel

Filament-wound fibreglass — nothing in it to rust, built for continuous wet-service duty.

Specifications

Capacities & configuration

Specification	Detail
Stage	3 of 4 — polishing
Flow rates	8.8 to 440 US gallons per minute
Media	Granular activated carbon, coconut shell
Bed	Full depth — no sand or gravel layers
Principle	Adsorption onto the carbon's internal pore surface
Removes	Odour · colour · dissolved organics · surfactant residue · residual hydrocarbons · chlorine
Sized on	Contact time at your design flow
Vessel	FRP filament-wound pressure vessel
Plumbing	PVC — rust-proof
Control valve	Multiport — service / backwash / rinse
Cleaning	Automatic backwash and rinse — lifts fines; does not regenerate the carbon
Media change	On breakthrough, not on pressure drop
Pump	None required — runs on Stage 2 pressure
Controls	Fully automatic, built into the skid
Connects after	Multimedia filter (Stage 2)
Feeds	Resin water softener (Stage 4), or back to the wash

Questions we get

Activated carbon filter — common questions

How do I know when the carbon needs changing?

Your nose, mostly. Carbon saturates rather than clogging, so odour and taste break through before anything shows on a pressure gauge — a rising smell in the recycled water is the signal, not a manifold reading. Once we have seen your first exhaustion we can set a media interval from it and work to that instead.

Does backwashing regenerate the carbon?

No. A backwash lifts out fines, breaks up channelling and re-loosens the bed, but whatever the carbon has adsorbed stays adsorbed. When the bed is exhausted the media is replaced, and spent carbon can go for thermal reactivation. That is the real difference from Stage 2, where a backwash genuinely restores the bed to its clean condition.

Does it help with foaming?

Yes — and for a lot of sites that is the actual reason they need it. Shampoo and degreaser surfactants carried over from the wash stay dissolved straight through settling and sand filtration, then foam in the tanks and in the bay. Adsorbing them is what takes the foam out of a recycled loop.

Why coconut-shell carbon rather than coal-based?

Pore structure and hardness. Coconut-shell carbon is dominated by micropores, which is the size range that suits the small dissolved molecules in wash water — surfactants, odour compounds, chlorine. It is also physically harder than coal-based carbon, so repeated backwashing generates fewer fines, and it is made from an agricultural by-product rather than mined coal.

Does it need its own pump?

No. Stage 3 connects in-line and runs on the pressure the multimedia filter already delivers, which is why it is straightforward to add to a W100 line that is already installed and running.

Will it remove hardness, scale or white spotting?

No, and it is not meant to. Hardness is dissolved mineral salts and carbon does not adsorb them — that is the resin softener's job (Stage 4). Carbon handles odour, colour, dissolved organics, residual hydrocarbons and chlorine. If you are getting white spots on dry panels, you need Stage 4, not more carbon.

Can I run it without the multimedia filter in front?

Not sensibly. Suspended solids blind the carbon surface and plug the bed, so the carbon exhausts on dirt instead of doing the job you bought it for — and carbon is the more expensive media by a wide margin. Stage 2 is what makes Stage 3 last.

The W100 system