|Growth of VTF Constructed Wetland Over Time|
A VTF was installed on a large lot with very poor soils and a failed onsite system.
Soil in the install area consists mainly of imported marine clay
Vegetative Tertiary Filter (VTF) before planting
Planted area is 3.5 m x 3.5 m (12 ft x 12 ft)
10 months after installation
Two years after install, cattails now are 4.5 m by 4.5 m (15 ft by 15 ft), a 56% increase in area, with a concomitant increase in the rhizosphereThe rhizosphere is the portion of soil that surrounds plant roots. Plants secrete proteins and sugars which many bacteria feed on. Abundant protozoa and nematodes graze on bacteria in the rhizosphere. Much of the nutrient cycling and disease suppression needed by plants occurs immediately adjacent to their roots. Recalcitrant (hard to break down substances) are consumed there. So the rhizosphere is the most biologically active soil zone. Direct oxidation of the simpler compounds occurs in the Nayadic treatment plants, but it is the rhizosphere and its intensive biological activity that removes trace contaminants from wastewater. Central discharge of even treated wastewater - be it to the water table or to surface water bodies - does not expose the trace contaminants such as endocrine disruptors, pharmaceuticals, or personal and household, commercial, and industrial care products to a rhizosphere. VTF promote extensive rhizosphere development hence protect the environment far better than does most other treatment mechanisms.
Oct 2007 - Cattails now measure 7 m x 7 m (24 ft x 24 ft) a four-fold increase in size
VTF constructed wetland is now about 9 m x 9 m (30 ft x 30 ft) which is over 6 times larger than its original area. The cattails are turning what used to be clay soil into biologically rich top soil
Seven years after constructed wetland was installed, size is now about 12 m x 12 m (40 ft x 40 ft) - over 10-times its original size
Unlike conventional PVC plastic pipe dispersal fields, biological systems can expand, growing according to the amount of water and nutrients received. As they grow, they improve the soil. A plastic pipe just sets there, slowly plugging up, necessitating ongoing maintenance.