|
operating home |
Operating guidelines for AFM filters |
|
Applications |
|
water flowrate
cubm hr-1 m2 |
(1)Back-flush flowrate
cubm hr-1 m2 |
Back-flush duration
minutes |
(2)Backflush frequency |
| drinking water |
optimum |
5 - 10 |
Back wash flowrate flowrate should be between 40 and
45 cubm/hr/squm This flowrate applies to sand as well as AFM and is
required to fluidise the bed by up to 15%. If you do not
fluidise the media the filter will not be properly cleaned |
4 - 8 |
1 to 2 times per day |
| maximum |
10 - 15 |
|
|
| swimming pool |
optimum |
10 - 15 |
4 - 8 |
1 times per week or every
second week |
| maximum |
15 - 30 |
|
|
| sewage treatment and industrial effluent |
optimum |
1 -5 |
2 - 4 |
4 to 8 times per day |
| maximum |
5 - 15 |
4 - 8 |
|
| river, lake and sea water |
optimum |
5 - 10 |
4 - 8 |
2 to 4 times per day |
| maximum |
10 - 30 |
|
|
| Aquaculture |
optimum |
5 to 15 |
4 - 8 |
2 to 4 times per day |
| |
maximum |
10 to 30 |
|
|
| Public aquariums |
optimum |
5 to 15 |
4 - 8 |
1 times per week or every
second week |
| |
maximum |
15 to 30 |
|
|
| Landfill Leachate
|
optimum |
1 to 5 |
4-8 |
6 times per day |
Notes
- Bed expansion should be around 150mm for a 1m deep bed.
- In some cases such as the removal of iron and manganese from water supplies, it can actually be more effective to use a short back-flush and allow
retained metals and solids to stay in the bed. The retained solids can in some cases improve the performance of the filter. For example, if
there are diatoms ( algae) in the water, the diatoms will improve filter performance, but the pressure head will also increase. For
critical applications such as swimming pools and drinking water, the back-flush should continue until the water runs clear. On average AFM will remove
around 50% more solids from the water than a sand filter, so the back-flush times end up being similar, but almost twice as much solids are removed
from the water.
- Air scouring for 5 minutes prior to back-flushing is recommended for all applications, however unlike sand air scouring is not essential for
AFM, although it does improve performance.
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