Aluminum is a soft, silvery metal commonly found in stormwater in both a dissolved (Al3+, Al(OH)4–) state and a particulate state. Aluminum is present in many soil types and minerals and is generally present in ground and surface water at low levels.[vii] Acid rain can dissolve aluminum in soils and transport it via runoff into water bodies in a dissolved state.[viii]
The primary uses of aluminum in industry include auto parts, beverage cans, home construction and aluminum foil.[xii] Aluminum compounds are added to sewage to facilitate phosphate removal and as part of the paper production process.[xiii] Aluminum in these forms can make its way into waterways and human freshwater drinking sources through stormwater runoff.
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Aluminum should be removed from stormwater because of its negative effects on humans and wildlife. When ingested through a water source, high concentrations of aluminum intake are associated with vitamin deficiencies, nerve damage and cancer.[i] People with kidney damage are particularly susceptible to aluminum toxicity.[ii]
In the environment, dissolved aluminum is toxic to plants as it affects roots and prevents nutrient intake.[iii] In acidic waters (pH 5.0-5.5), aluminum is toxic to fish at 0.1 mg/L.[iv] Dissolved aluminum interferes with fish gill functions and can cause fish to lose electrolytes.[v]
Aluminum in stormwater exists primarily in a solid, particulate form. Enhanced, passive media filtration and polishing can be used to effectively remove particulate aluminum from stormwater prior to discharge to help facilities meet benchmarks or NALs. The Aquip passive media filter and the Purus metals polisher combined offer an advanced level of aluminum removal from stormwater. Learn more about our stormwater media filtration and polishing technologies.