Constructed Wetland treatment offers a low cost natural process for stormwater treatment using local resources in the correct circumstances. The natural biological systems relies on wetland plants and micro-organisms as the active agents in the treatment processes.
These wetland systems are typically tertiary treatment devices for stormwater but increasingly considered for broad catchment or even flood plane treatment devices.
It must be said that there is a significant drawback for wetlands by the quantity of contaminats being loaded from decaying organics and rubbish overlays, sediment layers and heavy metal deposits over the floor of the wetland with high turbidity levels and hydrocarbon contamination that inhibits aeration of the water body. Thus there is a strong need to manage the intake to the wetland and be able to maintain a sustainable biological treatment process for the longer term. To optimise this tertiary treatement additional measures at the intake of the wetland need careful design matched to the contaminate load of the catchment that the wetlands support.
Natural biological process must be maintained at a level that can be treated by the charastics of the wetland. Organic filtration and ponding bays at the head of the intake may be used to capture sediments and reduce other contamination inhibitors for the wetland survival like hydrocarbons and algal blooms. Maintenance then is at issue as it is difficult to adequately decontaminate the wetlands and at the same tiome maintain the biological eco-systems to continue the treatment process.
Designs of wetlands is not widely practiced and tend to overlook the loading of contaminates and the effects on the ecology of the water body such that it is prudent to implement product that infact optimise the water quality prior to the feed water entering the wetland and utilise a system of contaminate removal, even beyong the ubiquitious GPT as a stand-along measure of water quality improvement which often it fails to achieve.