Coarse Filtration

Coarse Filtration: The front end of every water treatment system

PureTec has extended its UK water treatment offering upstream. Where our existing range focused on fine filtration, membranes and reverse osmosis (RO) from around 1 micron down, we now also design, supply and service coarse filtration from 10mm at the intake through to that 1 micron handover. One partner, one designed train, from the source through to ultra-pure water.

What coarse filtration covers

Coarse filtration sits at the front end of any water treatment system, between the raw source and the membranes, resins and softeners downstream. Its job is to take out the things that would otherwise foul, block or wear out the rest of your plant.

That includes sand and silt from boreholes, organic fines and algae from rivers, leaves and surface debris, fibrous material, eels and elvers at unscreened intakes, and invasive species like zebra and quagga mussels.

The right setup makes the rest of your system run cleaner, longer and at lower cost.

Why the front end matters

When intake filtration is undersized, missing or poorly matched to the water, the cost shows up downstream. More frequent membrane fouling, faster resin exhaustion, higher chemical use, more backwashing, and creeping maintenance bills. Sites often spot this as "old kit" or "operator error" when the real cause is starvation at the inlet.

A well-designed coarse filtration train reduces ultrafiltration (UF) and RO fouling, cuts chemical dosing, extends equipment life and lowers discharge volumes. It also addresses environmental risk at the source, protecting eel populations and stopping mussel veligers (50 microns plus) from reaching heat exchangers.

For a deeper look at how this plays out in power generation specifically, including the kinds of back-end problems that almost always start at the inlet, read Dan Norman's article: Why power stations underinvest in front-end water treatment.

PureTec's coarse filtration range

We design coarse filtration trains using equipment matched to the contamination profile and flow regime of your site. 

The core options include:

• Self-cleaning intake screens

Powered by return feed water under hydraulic pressure, so no electrical drive is needed at the intake. 

N+1 redundancy keeps flow steady if one screen fouls. The screen stops eels, fish, leaves and other large debris reaching the pumps, and is built in carbon steel or 316 stainless to suit the duty.

• Hydrocyclones

A vortex-based separator with only one moving part (the exit valve). 

Captures up to 97 percent of dense particles such as sand, rust and other material with specific gravity above 2.0. Works best where flow is steady, which makes it a natural fit for boreholes.

• Disc filters from our partner Azud

Stacks of polypropylene discs that backwash one pod at a time at 0.5 bar differential pressure, maintaining 100 percent forward flow through the cleaning cycle. 

Typical range from 200 micron down to 10 micron. Air-assisted versions reduce backwash water use from around 30 litres to 12 litres per cycle. 

Azud is a Spanish manufacturer, and we chose them as our disc filter partner because the kit is well built and their supply has stayed dependable through periods of market disruption that have hit other suppliers hard.

• Media filters

Large vessels filled with a filtration medium, usually sand or glass. They come in all sorts of shapes and sizes, and can have more than one grade of sand or glass in them to aid filtration. Very simple designs, and very simple to operate, they do require a lot more water to backwash than screens or discs.

• Drum filters

Drum filters run at very low pressure and present a large surface area to the flow. 

They are particularly good at lifting bulk sludgy material out of the stream before any final polishing stage, and find regular use in fish farming and hatchery duties as well as industrial pre-treatment.

• Screen and wedge wire filters

Manual, semi-automatic and fully automatic options for specific particle profiles and process applications, with proper attention to nominal versus absolute ratings.

• Band filters

A useful option where backwash water is too valuable to send to drain. 

Band filters recover it for reuse, and at the same time capture the solids on the filter cloth. On some sites those solids carry scrap value, turning what would have been a disposal cost into a small revenue line.

Where coarse filtration matters

Coarse filtration matters anywhere raw water enters a process or a treatment plant. 

We work with sites drawing from rivers and surface water, boreholes, lakes and ponds, seawater for cooling and process, and mains supplies with variable quality or aging infrastructure.

Common applications include power generation (CCGT, thermal and nuclear cooling), water utilities, pulp and paper, food and beverage manufacturing, irrigation, pharmaceutical, and data centre cooling.

How we work with you

Specifying coarse filtration properly needs hard data on the water you are actually treating. 

We start with a feed water analysis that gives you Total Suspended Solids (TSS) from proper lab analysis, Particle Size Distribution (PSD) across more than one sampling day, and a water quality classification across multiple factors. That data drives the specification.

From there we design, supply, install, commission and service the train. Skids and packaged plant can be containerised where space, programme or rental flexibility makes sense.

We also support what others have built. If your existing front end is underperforming, we will assess it against the actual feedwater rather than the original brief.

Free feed water analysis

If you operate a high water-use site and you have not reviewed your intake in the last five years, this is the place to start. 

We are offering free feed water analysis and intake assessments throughout 2026, with no obligation. You get the data, and a clear view of what your existing or future treatment train should be sized for.

Contact our team to scope a feed water analysis for your site.