Wetlands are the most biologically active natural ecosystems on earth and have proved to be very effective in treating wastewater. Haut Espoir’s wetland is located on the site of a small farm dam that burst during a winter storm in 2009.
According to Haut Espoir MD, Rob Armstrong, the wetland is designed for a daily peak flow of 6000 litres per day, which is sufficient to handle the peak effluent flow rate from the cellar. The outflow of the wetland is pure water. This water flows into what remains of the dam on the site to provide a habitat for frogs, insects and other water-loving fauna while the rest flows into a nearby stream.
The plantings on the wetland’s course gravel bed provide a substrate (stems, roots, leaves) on which microorganisms such as bacteria proliferate. It is during the contact between the effluents passing over the bacteria covered roots etc that treatment occurs.
Plant choices for an artificial wetland are crucially important. The selected plants have to be able to adapt to the local climate, be able to withstand high nutrient and pollutant levels, be resistant to pests and diseases and have deeply penetrating root systems. Ideally they should also be indigenous to the area. Haut Espoir’s wetland is planted with 3 sedges of the Cyperus genus and Wachendorfia thyrsiflora. The latter is indigenous and produces spectacular spikes of yellow flowers in spring adding colour to the wetland.