The use of a series of vegetated swales to provide filtering treatment for stormwater as it is conveyed through the channel. The swales can be grassed, or contain emergent wetlands or high marsh plants.

The use of vegetation (usually grasses or wetland plants) to filter and treat stormwater runoff as it is conveyed through an open channel or swale.

The harnessing of natural processes for volatile organic compounds (VOC) and odor control. Example: an air stream is passed through a biofilter containing microorganisms, which metabolize the VOCs, turning them into carbon dioxide and water.