Filter MediaComparison of Different Media Properties

Sand Silt Loam Compost Peat

Permeability (cm/hr) 3.3 0.1-0.4 - 0.25-140

Water holding capacity (cm/cm) 0.14 .07-0.1 - .01-0.2

Bulk density (g/cm) 2.65 1.25 1-2 ɘ.1-0.3

pH - 5.7 7.8 3.6-6.0

Organic matter (%) ə ង 30-70 80-98

Cation exchange capacity 1-3 12-18 66 183-265

Total phosphorus (%) 0 0.09 ɘ.1 ɘ.1

Total nitrogen (%) 0 0.15 ə.0 ɚ.5

Filtration efficiency after

18 in. (%) 93 94 16 47

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Many key pollutant removal mechanisms associated with filters are related to the filter media. For example, filtration, adsorption, and microbial action are all influenced by the media type. Selecting the appropriate medium can improve removal of specific pollutants. This slide shows some of the important properties for various filter media.