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Scrap
tires can be used to filter wastewater
Friday,
November 17, 2006
Crumbled
rubber tires can filter out pollutants
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Harrisburg, Pa. -- Every
year, the United State produces millions of scrap tires that clog
landfills and become breeding areas for pests. Finding adequate
uses for castoff tires is a continuing challenge and illegal
dumping has become a serious problem throughout the nation.
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."
Crumb rubber is produced by
chopping up and grinding up waste tires to a desired size,
cleaning the rubber and removing any metal particles. It is
currently being used in highway pavement, athletic track
surfaces, playgrounds, landfill liners, compost bulking agents,
various manufactured products, energy recovery and even as
artificial reefs for aquatic life.
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 has proved that crumb
rubber is not a rigid material; instead it can be easily bent or
compressed. 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 than conventional
sand or anthracite filters. Because of substantially higher water
filtration rates and lighter weight in comparison to sand or
anthracite, crumb rubber filters may also be used in a mobile
treatment unit for disaster relief operations, he adds.
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.
Also a
Professional Engineer, Xie holds a U.S. patent on the technology.
With more than 20 years of research experience in water and
wastewater treatment, he focuses his work on water disinfection,
disinfection byproduct control, water reuse and acid mine
abatement.
Source
/ Credit: Penn State University
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