air fans for backwash
air fans for backwash
(OP)
Guys,
In my limited experience in water treatment, I am seeing for the first time air fans used to assist in the backwash of filtering and softening equipement. How important is the pressurized air in fluidizing the beds? and is the backwash water pressure not enough to loosen the bed?
I am new to eng-tips and I am marvelled and humbled by the level of expertise on this forum.
Best regards,
Karbone
In my limited experience in water treatment, I am seeing for the first time air fans used to assist in the backwash of filtering and softening equipement. How important is the pressurized air in fluidizing the beds? and is the backwash water pressure not enough to loosen the bed?
I am new to eng-tips and I am marvelled and humbled by the level of expertise on this forum.
Best regards,
Karbone





RE: air fans for backwash
RE: air fans for backwash
RE: air fans for backwash
Water softeners do not use air scour because the ion exchange media has a lower specific gravity and the ion exchange media will float out with the backwash water. However, other ion exchange processes do utilize air for mixing the ion exchange bed.
RE: air fans for backwash
Steve Wagner
RE: air fans for backwash
-Close filter influent valve
-Allow filter to drain to below the washwater trough
-Close filter effluent valve
-Run blowers to agitate media without backwashing filter
-Shut off blowers as filter effluent valve is opened
-Continue with backwash without air scour
RE: air fans for backwash
RE: air fans for backwash
You must have an appropriate underdrain for air scour or you must install a grid type of system strictly for the air scour that lies on top of the underdrain or gravel support media.
DO NOT TRY TO FORCE AIR INTO AN EXISTING FILTER UNDERDRAIN THAT ISN'T DESIGNED FOR AIR. Not unless you want to blow it out of the filter basin.
As Bimr and SteveWagstated earlier, the air scour is very agressive and will improve the cleaning by giving the media more agitation to break up mudballs, etc. It also does it in a shorter time frame than water only and saves time and backwash water.
Media guards can also be incorporated into the trough design to help retain media at higher air/water wash rates.
Another hint is to bring the air header above the filter water level to prevent a leaking air valve allowing water into the blower.