Published on Apr 17, 2020
Air streams can be purified by passing them through a biologically active filter medium to destroy organic and inorganic contaminants. It is especially effective for low concentrations of VOCs and inorganic chemicals (e.g., sulfur compounds). It has proven effective for mixed waste air streams and especially applicable for odor abatement. Heavily halogenated compounds present problems
Biofiltration is generally effective for aqueous wastes where concentrations are less than 1%. As with all biological treatment, it requires stable, consistent operating conditions.
Biofiltration is not suitable for highly chlorinated organics, aliphatics, amines, and aromatic compounds. Heavy metals and organic chemicals may kill the microorganisms. Heavy metals and non-biodegradable organics may also concentrate in the sludge. Hydrogen sulfide gas may also be released. Biofiltration swales and strips are vegetated areas that remove pollutants from storm water runoff as it flows through the vegetation.
Removal mechanisms include filtration and infiltration. In this study, one biofiltration strip and six swales treat highway runoff, while two strips treat runoff from maintenance yards (for pretreatment for infiltration trenches). Runoff is captured in drain inlets and routed to the swales, while strips receive sheet flow directly from the pavement. Swales are conveyance channels where storm water flow passes through the grass. Strips are broad surfaces with a grass cover that allows storm water to flow in relatively thin sheets.
Biofiltration swales and strips are providing useful information about vegetation that can filter storm water pollutants effectively in dry areas with little rainfall. These biofiltration devices can also be used for pretreating storm water going to infiltration BMPs (i.e., trenches and basins). This "treatment train" approach can increase the overall effectiveness of storm water treatment.
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