Fixing A Filter Backwashing Problem


The first documented use of sand filtration to purify the water supply dates back to Scotland in 1804. Since then, the technique has been continuously refined by water professionals and those gradual tweaks have allowed it to stand the test of time.

The development of continuous backwashing filtration, made in the 1970s, was one such tweak. Traditionally, the sand filter would remove solids which settled into the filter until head loss or differential pressure increases indicated that no more water could be produced.  To restart the cycle, the filter had to be taken offline and backwashed. The new breakthrough, found in Parkson Corporation’s DynaSand, eliminated this step by automating media backwashing. However, it meant that the filter was always being backwashed, whether it was dirty or not. Another tweak to the DynaSand technology has solved that.

“We decided to make a hybrid of the two [types of filter],” said Parkson’s director of sustainability and innovation Dave Chew during an interview with Water Online Radio. “From the outside, it looks like a continuous backwashing filter, but we periodically turn on and turn off the backwash… When you go to turn the filter back on, we figured out a way to actually measure whether or not the sand is moving.”

To hear more about Parkson’s filtration innovation and more, tune in below.

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