Constructed Wetlands: A Sustainable Future Alternative to Wastewater Treatment under Climate Change

In India, 38,254 MLD of wastewater is generated from class I cities class II towns but the treatment capacity is only of 12,000 MLD (Central Pollution Control Board) and rest of the water remain untreated. So, this technology is proposed for utilizing the unused water in supplementing the resources by constructing wetlands. A project carried out at Indian Institute of Technology, Powai underscored the fact that the Constructed Wetland systems can be effectively combined with advanced tertiary treatment alternatives and the resulting high quality treated water can be successfully recycled into water production and sanitation applications. Wetlands are marsh-like ecosystems with proven capabilities in treating wastewater with physical, chemical and biological processes. A constructed wetland (CW) is a man-made, engineered, marsh-like area designed and constructed to treat wastewater in the same manner as a natural wetland. Constructed Wetland consists of a properly designed basin that contains water, a substrate, and, most commonly, vascular plants. Other important components of Wetlands, such as the communities of microbes and aquatic invertebrates, develop naturally. Natural wetlands act as a biofilter, removing sediments and pollutants such as heavy metals from the water, and constructed wetlands can be designed to emulate these features. It is a practical alternative to mechanical wastewater treatment and water quality requirements, especially in remote areas. The classification of constructed wetlands is based on: the vegetation type (emergent, submerged, floating leaved, free-floating); hydrology (free water surface and subsurface flow); and subsurface flow wetlands can be further classified according to the flow direction (vertical or horizontal).Under climate change adaptation issue and management of wetlands and water bodies become very important. The plants that are most often used in constructed wetlands are persistent emergent plants, such as bulrushes (Sciprus), spikerush (Efeocharis), other sedges (Cyperus), rushes (Juncun), common reed (Phragrmites) and cattails (Typha). Compared with the conventional treatment process, constructed wetlands provide advanced wastewater treatment that is highly valued but is of low cost in terms of investment, operation, and maintenance. When properly designed, constructed wetlands offer a number of other advantages, including, simplicity of operation, and effective removal of Biological Oxygen Demand and Total Suspended Solids. When sized adequately, constructed wetlands are also tolerant of fluctuating flows and variable water quality. Thus constructed wetlands are a promising, cheap and effective wastewater treatment in small communities. They are easily implemented and once constructed; enhance flora and fauna, increase plants’ diversity, and present favourable habitats for birds. Moreover, wetlands have negligible effects on air quality since polluted water circulates underground, preventing odours appearance. With continuous monitoring of the data obtained with the maintenance will result in success of the system. Impact of climate change will lead to less number of rainy days but more precipitation. It will result to water logging and constructed wetlands are put in place to utilize the surplus run off.