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Biological Wastewater Treatment Units

Please click here to download the SAF Wastewater Treatment Brochure

Wastewater Treatment SAF-Compact-Plants.jpg WPL’s biological treatment solutions can be used either to undertake full biological treatment or to complement existing process units.

As a leading supplier to the UK’s water PLCs and the commercial market, our biological treatment units are designed and manufactured to the highest standards. Our goal is to work with you to create the solution that fully meets your needs.

Submerged Aerated Filter (SAF)

Thanks to a combination of fixed film and suspended biomass reactions, WPL SAF modules meet even the most stringent of the consent standards imposed by the UK’s Environment Agencies.

Manufactured from GRP or steel, WPL SAF units can be installed below or above ground, with full access to all parts of the unit. All mechanical and electrical equipment is located in a separate, dedicated enclosure for easy maintenance.

The units are suitable for permanent or temporary applications, with a number of different hire and purchase options to suit your requirements.

Why choose WPL SAFs?

Consistent process reliability sub 1mg/l ammonia and 10mg/l BOD
No internal moving parts mean safe working access for maintenance
Hire purchase options to suit your budget
Flexible hire periods
Low operating costs
No need to de-sludge – unit is self-scouring

How the SAF works

WPL SAFs use a combination of fixed and fluidised bed and suspended biomass reactions. Flow from the inlet will gravitate through the segmented sections of the unit filled with randomly packed plastic media, where carbonaceous, nitrifying and de-nitrifying (optional) processes take place. Air to oxidise the influent and to scour excess biomass from the filter is introduced continuously below each chamber by a series of diffusers. Each diffuser can be removed for maintenance without the necessity to shut down the plant. Inert excess biomass scoured from the media pack will rise to the surface and gravitate to the outlet with treated effluent, for final settlement.

Internal configuration

WPL SAFs are available in optional GRP or steel structures for below and above ground applications. The structures are filled with randomly packed plastic media, and the filters are segmented to replicate a‘plug flow’ arrangement, and eliminate the risk of shortcuts. Plastic air diffuser pipework is incorporated throughout, to eliminate risks associated with corrosion. The pipework distributes air evenly from the base of the unit through the media pack. Each diffuser can be isolated and removed without the need to shut down the plant or affect the air supply to the rest of the unit. Access for maintenance is enhanced by WPL’s unique lid design, which allows safe working access and visibility from the top surface level.

There are no mechanical or electrical moving parts within the hostile environment of the unit. All blowers and control equipment are located in a remote, purposely designed kiosk or enclosure, away from the treatment area.

WPL SAFs come in three formats:

Aerated fixed film
Aerated fluidised bed
Anoxic fixed film (used in conjunction with 1 for specific applications)

These formats are utilised for the following applications:

Secondary SAF

For settled liquor from septic tanks and primary settlement tanks
Carbonaceous and nitrifying applications
Segmented filter with first segments containing 140 m2/m3 media(roughing) and subsequent sections containing 210 or 300 m2/m3 media

Tertiary SAF

For polishing liquor from existing biological treatment units where carbonaceous BOD has been partially reduced, but where further BOD and nitrification are required to meet consent standards.
Segmented filter with first segments containing 210 m2/m3 media and subsequent sections containing either 210 m2/m3 or 300 m2/m3 media (optional)

N-SAF(A) (ammonia only)

For applications where the carboneous BOD has been completely removed (below 20 mg/l average), but effluent is required to be fully nitrified, and further biological capacity is required for this application. Two types of filter are offered for this application:

Fixed bed - Modelled on the above tertiary plants where the media can be either 210 or 300 m2/m3

Fluidised bed bioreactors - Hi-rate SAFs containing higher specific surface area – typically 700m2/m3 media

N-SAF(N) (Total N removal)

Pre- and post-anoxic treatment possible, in combination with standard aerated process.
For applications that require secondary carbonaceous, nitrifying and de-nitrifying (Total N) treatment, where the anoxic segments are NOT aerated, but will be periodically scoured. Anoxic filters are filled with 140 m2/m3media, aerated sections filled with 210 m2/m3 media.
Recirculation between aerobic and anoxic sections is possible, either with integral pumps or air lifts (preferred).

Scope of supply

Range of standard sizes available, as well as bespoke design
Duty or duty/stand-by blower
Flanged inlet and outlet connection
Valve drain connection
Acoustically lined kiosk housing air blower and control panels that can be designed to specific requirements
Form 2 panel supplied as standard on hire units; upgraded panel specification available on request
Top level access safety lids (utility company approved) with high level safety grids, stainless steel hardware, non-slip pads
Several of de-sludge points
10m of air hose (additional air hose available on request)

Only from WPL

We will do everything we can to ensure that our SAF solution meets your needs. Our service includes:

Process design, on-site mechanical and electrical installation, setting to work and commissioning of the unit
Service contracts tailored to specific site requirements

Typical applications

Water utilities
Commercial or industrial wastewater solutions

Here to Help

We hope you can find everything you need here on our website but if you have any questions, please don't hesitate to call us on 023 92242 600 or email enquiries@wpl.co.uk – we'll be happy to help.