Downstream Mitigation

Downstream Mitigation

Downstream Mitigation and Pollution Removal
Storm-water and wastewater both have high levels of excess nutrients and other materials that if not extracted from the water stream become environmental pollutants. The natural processes established in Designed Ecosystems are effective at removing these potential pollutants through biological degradation, filtration, sedimentation and adsorption. The contaminants of most concern include organic compounds, suspended solids, excess nutrients (nitrogen and phosphorus), sediment, metals and pathogens.

Biological Oxygen Demand (BOD)

Requires aerobic environments

Organic molecules, such as those found in solid human waste, and other substances that require large amounts of oxygen in order to be broken down constitute BOD. When BOD is released into a natural environment its decomposition can rob fish and wildlife of needed oxygen. A constructed wetland will mechanically filter out most solid BOD as it passes through sand, soil, crushed rock or brick, while dissolved BOD is eaten by microbes. Microbes colonize on the surfaces of plant roots where oxygen is made available as plants photosynthesize and transport oxygen from their leaves to their roots.
Total Suspended Solids

Suspended solids are the non-living organic and inorganic particles remaining in the water column. Suspended solids, like sediment, increase the turbidity of water, reducing light penetration and thus inhibiting plant growth. Suspended solids may clog the gills of fish and other aquatic organisms, and potentially toxic organic compounds and metals bind to the suspended particles.