| Schematic of a surface water treatment system for drinking water. The diagram shows pressure AFM filters, however they could equally be RGF ( Rapid Gravity Filters). In most system there will need to be some correction of the water chemistry. The scheme presented below gives an example of a possible arrangement. |  | ZPM = zeta potential mixer
ZPMr = zeta potential mixer with resonator
System specification. water flow through the AFM®filters, 5 to 10 m3 hr-1 m2 of filter bed surface area recommended filter air purge rate 90 m3 hr-1 m2 of filter bed surface area back-wash flow rate 40 to 60 m3 hr-1 m2 of filter bed surface area
Benefits from AFM- Single pass filtration irrespective of the influent water quality, negate the need to use activated carbon, ozone or UVc
- Better performance than ultra membrane filtration because it removes dissolved organics. Nominal filtration at 1 micron with organics removal using AFM®. Absolute filtration at 0.03 micron with ultra filters but no organics removal.
- Reduce chlorine consumption by up to 80% and virtually eliminate THM`s, applies to double filtration systems with pre-chlorination prior to second stage filters.
- AFM®does not channel so when used with good coagulation and flocculation you have a much more effective barrier to the passage of oocysts than is possible with sand.
- Up to 75% reduction in back-wash water, the back-wash is predictable over years, unlike sand which has a variable back-wash reaction.
- Public health and environmental benefits are huge, sand filters incubate bacteria and pulses macro bacteria floc as well as iron & manganese and other contaminants back into the water. AFM®filters are stable
- How to use AFM®, it is a direct replacement for filter sand, nothing else in the system needs to change.
- Cost, well it costs more than sand but we are still dealing with a relatively low cost product which will give a return in capital in under 12 months.
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