What is an Integrated Constructed Wetland?
An Integrated Constructed Wetland (ICW) is a Nature Based Solution (NBS), which comprises of a series of shallow cells that are connected in series via pipework and densely planted with a variety of emergent wetland vegetation.
Designed to ‘integrate’ into their environment, ICWs are specifically designed on a case-by-case basis, depending on features such as topography, hydrology, geology and ecology within the target area.
This multi-disciplinary approach incorporates the natural interactions of water, land and air to provide total management of contaminated waters from various sources.
How does an ICW work?
ICWs mimic natural wetland systems and through biogeochemical processes (sedimentation, sequestration, uptake, absorption), strip through-flowing waters of their contaminants. ICWs utilise these natural processes to achieve high treatment efficiencies, with little to no requirement for energy input or hard engineering. ICWs can be fed from a variety of sources such as a factory, farm, village or a river, depending on the needs of the client. Upon entering the system, waters will flow sequentially through each cell, prior to discharging into the receiving environment. Additionally, ICWs can be designed to achieve zero discharge.
As the influent passes through the ICW, a variety of natural processes ensure that the water is adequately treated in a sustainable manner. Processes such as evapotranspiration, nitrification, denitrification, absorption, adsorption, sequestration, active plant uptake and microbial degradation, ensure that influent is appropriately treated without the requirement for electromechanical processes. ICWs strive to optimise these naturally processes in order to achieve the best possible treatment outcomes, regardless of source waters.
Benefits of an ICW - Ecosystem Services
Ecosystem services are described as the benefits that us humans receive from the natural world. They can come in different forms such as provisioning, regulating, cultural and supporting services. ICWs provide a variety of ecosystem services such as carbon sequestration, habitat and biodiversity enrichment, nutrient cycling, wastewater treatment and flood alleviation. Additionally, ICWs provide a host of amenity, education and eco-tourism opportunities. These services are an inherent part of the ICW concept, meaning that they will be present in some capacity, regardless of the specifics of the design.
Performance
The management of natural contaminants is a process that is billions of years old. The application of these natural processes in an ICW utilise natural efficiencies in the management (treatment) of contaminated waters in a sustaniable manner which is complimentary to the surrounding environment. As a direct result of working with nature rather than against it, ICWs are capable of treating a variety of contaminants such as suspended solids, phosphorus and nitrogen, to emerging substances such as pharmaceuticals, microplastics and heavy metals.
