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Tertiary treatment of sewage effluent home
Standard scale systems
Standard scale AFM systems can cope with water flowrates up to 50 cubic metres per hour and solids load up to 200 mg/l. The AFM system can be used in
virtually any water type from sewage effluent to many types of industrial waste water. The system are also used in clean water applications, because AFM removes
30% more solids from water than can be achieved by using sand.
AFM filtration systems from Dryden Aqua provide for the first time an easy, inexpensive means of improving effluent water quality by 90%, in terms of COD and
solids load. Major saving s can be made on water costs, discharge costs and process system benefits, payback is usually measure in months.
| The process The standard scale systems cover a water flowrate
- 5 to 10 cubm/hr
- 10 to 20 cubm/hr
- 15 to 30 cubm/hr
- 25 to 50 cubm/hr
The system will cope with clean water application such as river or lake water However unlike sand filters, AFM media and systems will also
cope with grossly contaminated water with solids load up to 4000 mg/l. The high solids load will have no impact on the AFM. However from a
practical perspective, it is best to use some basic sedimentation prior to AFM to reduce to solids load down to at least 200mg/l. However if
this is not possible, such as in the removal of yeast or algae, then AFM will cope with the full loading.
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| Design The system can be provided as a skid mounted control system connected to an
external pressure or rapid gravity filters. Alternatively everything can be constructed inside a 20ft ISO container. |
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| Control system The AFM filtration system is controlled by a PLC built into the
panel. The system is completely automatic and requires no operator intervention.
Numerous sensors on the system are constantly monitoring pressure conditions, filter bed quality, tank levels and pump condition. A flow
monitor checks the water flowrate and the PLC is constantly making minor adjustments to the run phase pump to keep the flowrate constant +/= approx. 1
% of the desired flowrate.
The system is fitted with alarm out-puts for integration to your site management system. Alternatively an optional extra interface can allow
remote operation and interrogation of the system via the internet.
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| Position of system in Process AFM systems have been designed to cope with very
high loadings, as such they can be located before standard sedimentation humus tanks. There is therefore less requirement for a humus tank stage
in sewage works using AFM. " High load pre humus tank filtration Techniques are covered by our IPR"
The AFM filter is back-flushed automatically at regular intervals, a mass balance can then be conducted on the quantity of solids removed by the
filter and back-flushed back out of the filter.
In the case of sewage works effluent, the back-flushed water has a solids content between 2000 and 4000 mg/l. The sludge is kept in an active
aerobic condition and can either be recycled back to the beginning of the works, or de-watered for sludge disposal.
We have found that removal of the bacterial sludge by AFM before it is subjected to the anoxic conditions in the humus tank, prevents the release
of prescribed substances back into the water. This aspect of AFM process provides us with an effective relatively inexpensive tool
to prevent the discharge of toxins to the environment.
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AFM back-flush water, and the same water after about 2 minutes, not the excellent sedimentation and healthy floc
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| Effluent water quality After the AFM filtration the discharge level was reduced to
around 5mg/l, almost irrespective of the quality and type of water entering the AFM filter.
Flocculation
If flocculation is used on the system, discharge water quality can be improved to less than 1 mg/l
Phosphate removal
AFM systems can virtually eliminate final effluent phosphate by using ferric chloride or by using NoPhos which is
under development
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Sewage effluent water before and after AFM filtration
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