- Micron-precise depth filtration of solids
- Innovative disc technology captures and retains large amounts of solids
- Long-term operation with minimal maintenance
- Easy and simple operation
- Short automatic backwash with regulated minimal water volume
- Compact design
- Modular arrangement – unlimited upscaling for flow filtration degrees from 400 to 20 microns.
The Amiad range of disc filters comprises sets of plastic discs stacked onto a hollow spring loaded spine. The raw water passes through the discs from the outside to the inside, trapping suspended solids between the layers as it does so.
Multiple disc filter ‘pods’ can be supplied on pre-made manifolds, in what is known as ‘batteries’, to allow large flow rates.
The design of the grooves on the discs means that the filtration is ‘multiple pass’ – in other words, the water passes through several spaces of the filtration size before it reaches the spine, giving several chances for particle capture, unlike screen filters which present one pass only.
Backwashing can be done in one of three ways: using the forwards flow of the process, passing through a secondary second filter first; using a separate external pump; or, by using air from an external compressor to drive the backwash water, reducing backwash time to <10 seconds and regulating water volume used.
When arranged in a battery, only one module washes at a time, ensuring minimal to zero change in downstream water flow.
The Filtering Process
Raw water enters the filter housing and passes through the stack of discs to the hollow spline, and from there exits the filter. Suspended particles in the water are trapped by the discs. A spring on the spine holds the discs clamped together to ensure the degree of filtration is achieved. Forwards water pressure assists this spring.
The filtering process is monitored on each module by a pressure differential switch, which will automatically trigger backwashing of the module once the preset pressure differential has been passed.
The Cleaning Process
Cleaning of the filter is initiated by the control system, activated by pressure differential, time or manually. Upon activation, the valve configuration at the base of the module closes raw water to the inlet, and filtered water to the outlet, then connects the inlet to a waste drain.
Backwash water from one of the sources outlined below is then connected to the outlet. The pressure of this water entering the spine causes the spring loaded part to lift, releasing the clamping pressure on the discs, allowing them to separate.
The spline also has directional jets on it; these jets cause the discs to spin, releasing any dirt particles attached to them. Due to their design and the design of the spline, the discs do not contact the spine while they are spinning, ensuring no wear and a long lifetime.
The module is then returned to forwards flow
In the case of a battery, this process is then repeated for the other modules.
The backwash water is sourced from the outlet manifold of the battery. In the case of a single module, this comes from the raw water, via a fixed filter screen. This system requires a pressure differential from the outlet manifold to the waste manifold of at least 2.8 bar
The filter battery has an additional manifold on it for connection to an external backwash pump. The pump will supply filtered water to the backwash manifold at the required pressure. This allows lower operating pressures as the process supply pump does not need to provide the backwash power.
An extra module added onto the battery provides a reservoir of filtered water ready to be used for backwashing. This water is charged with compressed air from an external compressor. When backwashing is required, the compressed air mixes with and drives the water out of the reservoir and through the disc module. This gives enhanced cleaning power, particularly on fine filtration degrees, as well as reduced backwashing time – typically 7 seconds.
For further information or to obtain a quote, contact us.