Media Filters

Stormwater media filters are usually two-chambered including a pretreatment settling basin and a filter bed filled with sand or other absorptive filtering media. As stormwater flows into the first chamber, large particles settle out, and then finer particles and other pollutants are removed as stormwater flows through the filtering media in the second chamber. The application of a media filter can be customized to target site-specific pollutants. A combination of media is often recommended to maximize pollutant removal effectiveness. Peat, compost, geotextiles, perlite, zeolite, and activated carbon are media have been used as filter cartridges for stormwater treatment.

Media filters clog easily when processing stormwater with high sediment loads. Placing vegetated buffer strips or vegetated swales in upstream of the filter, as sediment-reducing pretreatment practices, can reduce sediment loads into the filter.

Basic housekeeping practices such as removal of debris accumulations and vegetation management (in the filter media) can prevent clogs and breeding of mosquito and midge in ponds of standing water. Waste sand, gravel, filter cloth, or filter media must be disposed of properly and in accordance with all applicable laws.

Click here for the detailed design of media filters from the EPA’s Storm Water Technology Fact Sheet: Sand Filters

Click here to view the removal efficiencies of media filter systems.

Source: Shaver, 1991.(EPA Media-Filter Fact Sheet)

Copyright @ January,2005 Prepared by Transportation Environmental Resource Center (TERC)