backwashing

Downtown Houston probably high enough to not get a lot of this backwashing water so to speak coming up the ship channel, but, Anderson, there could be 10 inches of rainfall there in Harris County, and that could cause flooding with freshwater.

CNN Transcript Sep 12, 2008 2008

Conventional filter backwashing as applied in rapid sand filtration is not possible since the filter bed of roughing filters cannot be fluidised.

8. Classification of roughing filters 1996

While rapid sand filters require cleaning by rather complicated backwashing operations, slow sand filters are cleaned by the relatively simple periodical removal of the top of the filter bed, including the schmutzdecke.

8. Water treatment 1992

All production wells must be developed to remove drilling cuttings and mud which has migrated into the well wall and into the aquifer during drilling and to remove fine silt and sand from the aquifer around the screen to produce a coarser and more uniform gravel envelope around the production well; this may be accomplished by a variety of procedures including pumping, surging, injection of compressed air and backwashing.

6. Water sources, their protection and development 1992

For smaller plants in rural areas, simple rapid filters - without backwashing capabilities - are recommended.

3. Technologies 1985

The cleaning of the rapid filter is facilitated by backwashing i.e., by reversing the flow direction; a backwash may be conducted simply with water or by use of a water-air mix (upward air scour).

3. Technologies 1985

In the latter case 'though, backwashing by means of simply draining the water in a reversed direction may become increasingly impossible.

3. Technologies 1985

Addition of coagulant to inflowing water prior to sedimentation; flocs are retained by the filter; backwashing is difficult.

3. Technologies 1985

This is due to the need for frequent filter washing which requires elaborate backwashing systems.

3. Technologies 1985

Conventional backwashing capability may have to be added.

3. Technologies 1985