Scrap tires used to filter wastewater
Dr. Yuefeng Xie, associate professor of environmental
engineering at Penn State Harrisburg, has developed a method that
uses crumb rubber to filter wastewater, which can help ease the
tire problem and clean up the environment at the same time.
"My research has found that crumb rubber,
derived from waste tires, can be used as a filter media," Xie
explains. "The crumb rubber could be used for treating wastewater,
ship ballast water, and storm water."
For traditional wastewater filtration, gravity
downflow granular filters using sand or anthracite as a medium are
commonly used. One major problem with these filters is that upon
backwashing the particles, the larger ones settle at a greater rate
than the smaller.
The Penn State researcher explains that this causes
the top of the filter bed to hold the smallest medium particles
and the bottom to hold the largest with the small medium particles
or top layer of the filter tending to become clogged quickly.
In his research, he proved that through the crumb
rubber method, the larger solids are removed at the top layer of
the filter and the smaller solids at a lower level, greatly minimizing
the clogging problem.
Several studies conducted by Xie show that the
crumb rubber filter is much more cost effective and of lighter weight
in comparison to sand or anthracite.
Because the crumb rubber is compressible, the
porosity of the particles is decreased which resembling an ideal
filter medium configuration. It can then be used at higher filter
rates while performing similarly to other media now in use. The
crumb rubber media provide better effluent qualities and larger
media allow longer filter runs at higher flow rates.