![](backwsh1.jpg)
Flow to filter is stopped |
![](backwsh2.jpg)
Backwash is started and bed fluidizes |
![](backwsh3.jpg)
Backwash continues as long as required to flush
particles blocking flow from filter |
![](backwsh4.jpg)
Particles blocking flow from filter are now in
water above media |
![](backwsh5.jpg)
Backwash stops. Particles coated with biofilm settle into original pre-backwash position - on the
surface of the media |
![](backwsh6.jpg)
Water containing suspended particles is discharged
|
![](backwsh7.jpg)
State of filter after backwash
and discharge complete. Note that the particles with
biofilm are at the surface |
![](backwsh8.jpg)
Filtration
resumes |