Intellectual Property Office

Non-Confidential Disclosures

Method of Using Waste Tires as a Filter Media

PSU Invention Disclosure Number 99-2122

Field of the Invention/Key Words:

Crumb Rubber, filter media, wastewater filtration

Inventors:

Yuefeng Xie

Background:

Gravity down-flow granular filters are commonly used for wastewater filtration. In these devices sand or anthracite is normally used as a filter media. A major problem with these granular filters is that upon backwashing the filter, the larger particles will settle at a greater rate than the smaller particles. This causes the top of the filter bed to hold the smallest granular medium and the bottom to hold the largest granular medium. Problems arise in these situations since the smaller medium particles will have less spacing making it easier for the top to clog quickly during filtration. There is a need for a filter media which avoids fast clogging by decreasing porosity from top to bottom while still maintaining filtration quality. This need is addressed by the present invention.

Invention description:

The disclosed invention is a method of using recycled tires as a filter media. Waste tires are often recycled by creating crumb rubber which is currently being used in applications such as highway pavement, playgrounds, landfill liners, athletic track surfaces and various manufactured products. Crumb rubber is produced by chopping up waste tires then cleaning the rubber and removing any metal particles. The crumb rubber media is compressible, allowing the porosity between rubber particles to decrease through the filter bed (see Fig). Tests have shown that crumb rubber allows greater depth filtration, longer filter runs, less headloss and higher filter rates than current dual media filters. The crumb rubber compresses further as headloss decreases, allowing for better effluent quality late in the run. Filter rates of greater than 20 gpm/ft2 can be achieved with crumb rubber filters while still performing similar to traditional filter media in respect to turbidity and total suspended solids removal. The properties of crumb rubber media are closely tied to the media size and shape, smaller media provides for better effluent qualities and larger media allows for longer filter runs at higher flow rates.

Advantages:

• Increased capabilities of the filter with similar performance and less clogging
• Much higher filtration rates and much lower construction and operational cost than current mono or dual media filter.
  
• Applications for treating wastewater, ship ballast water, and storm water.
• Reduction of pollution caused by waste tires
• Broadly covered by issued US Patent 6,969,469

Contact:

Bradley A. Swope
Sr. Technology Licensing Officer
Intellectual Property Office
The Pennsylvania State University
113 Technology Center
University Park, PA 16802-7000
Phone: (814) 863-5987
Fax: (814) 865-3591
E-mail: bradswope@psu.edu