In addition, they do not have a favorable root structure for oxygen transfer or ideal root surface area for microbial growth.
Inlet/Outlet Devices Inlet and outlet devices and earth berms are used to control water depth in the wetland. These controls ensure uniform horizontal and vertical flow patterns through the planting medium, and maintain the water level below the surface.
Impermeable Liner An impermeable liner provides a separation between the wastewater treated in the bed of the wetlands and the surrounding area. The liner prevents leakage and contamination of groundwater. The impermeable layer may consist of an on-site or imported clay layer. In areas with permeable soils, a synthetic membrane or concrete liner is used.
Disinfection Constructed wetlands are adept at nutrient removal and suspended solids reduction. Like any treatment technology, the effluent from these systems should not be considered disinfected. Depending on the intended reuse application, additional disinfection by ozone, ultra-violet light or chlorine may follow constructed wetlands as a final stage in the treatment process.
Technology Constructed wetlands are designed to filter and treat contaminated water in much the same way as natural wetlands. As wastewater enters into the constructed wetland, it is treated both aerobically and anaerobically. The submerged plant roots combined with the surfaces of the gravel particles or other planting medium provide a substrate for the microbial processes necessary for treatment. The level and rate of treatment is proportional to the size of microbe populations and the contact time within the system. The combination of aerobic and anaerobic environments within a constructed wetland provides comprehensive treatment of wastewater, including removal of nitrogen and biological oxygen demand (BOD). These systems are typically designed to handle fluctuating flows and variable conditions without significant adverse effects on effluent water quality. Systems can be upgraded through the use of mechanical filters and ultraviolet disinfection to allow for water reuse applications.
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Toward Net Zero Water