PathShield™ Antimicrobial Filter Media

Removal of Waterborne Bacteria

The EPA website states, "In 1996, over 2,500 beaches in the United States were posted with warnings or closed for at least one day because the water was contaminated. Today, many beaches are either not monitored well or not monitored at all and consequently Americans continue to face risks of illness from swimming and other activities in coastal areas, lakes, and rivers that contain disease-causing microbes. By carrying out the Clean Beaches Plan, we are helping state, tribal, and local beach managers strengthen their programs. As a strategy for reducing the risks of infection to people who use our recreational waters, the Plan recognizes that beach managers need tools that allow for local and regional differences in pollution sources and climate. The Clean Beaches Plan describes what we plan to do over the next couple of years to achieve two major goals: promote recreational water quality programs nationwide and create scientific improvements that support timely recreational water monitoring and reporting." Click here to learn more on the 2004 Clean Beach Plan.

Technology Description
PathShield™ effectively reduces coliform bacteria without releasing, discharging, or leaching any antimicrobial agents, chemicals or heavy metals. PathShield™ kills coliform bacteria as the organisms physically move over the hostile surface of filter media granules (Figure 1). Efficacy is achieved at high filtration loading rates up to 20 gallons per minute per square foot (gpm/ft²). PathShield™ filter media is not consumed, requires no power source, has no moving parts, is non-corrosive, and is unaffected by seasonal temperature changes.
Figure 1. Bacteria is killed upon contact with hostile surface of PathShield™ media

Laboratory Testing
A number of independent efficacy tests were performed by a NELAP accredited laboratory certified to perform E. coli plate counts. Various influent surface area loading rates and test cartridges simulated over 400,000 gallons of water passing through 24 cubic feet of PathShield™ media on an annual basis.

Refer to the literature below where you will find summaries of the results of the laboratory simulations. E. coli concentrations ranged from 150 to 36,000 colony forming units per 100 milliliters (cfu/100 ml) while loading rates ranged from 9 to 118 gpm/ft². Efficacies of >99.9% or log three reductions, were achieved for these eight simulations. Additional independent long term laboratory efficacy challenges against E. coli were performed using 15 separate quality control PathShield™ filter media samples.

Field Testing
A series of independent filed verification tests were performed by university researchers using PathShield™ filter media within a full scale commercially available stormwater catch basin insert at an ultra urban location in Los Angeles, California.



Toxicity Testing
Comprehensive studies have been confirmed through the PathShield™ EPA registration that the media does not leach any antimicrobial agents, chemicals, or heavy metals and the effluent treated water is non-toxic.

Conclusions and Benefits
PathShield™ Antimicrobial Filter Media demonstrates superior performance for the removal of coliform bacteria in a variety of treatment applications including municipal waste water and stormwater runoff. EPA registration of PathShield™ confirms that coliform bacteria are physically killed as they pass through the media.

Significant operational and environmental benefits can be realized through the use of PathShield™ filter media including:

  • EPA registered antimicrobial filter media
• Media does not discharge, release or leach any antimicrobial agents
• Long term and high level of performance
• Does not rely on physical trapping
• No external power source or moving parts
• Media is non-corrosive and is not consumed
• Unaffected by seasonal temperature changes
Conclusion and Benefits of PathShield

Click any of the links below for additional information on PathShield, or if you would like more information or additional testing information on PathShieldAntimicrobial Media and how it can be applied to your project please contact us at 800-748-6945 with project details.

In Search of the Silver Bullet article

Tech Report 13.1 – Pathshield for Stormwater      May 2013

Tech Report 13.3 – Pathshield for Industrial Water      May 2013