A review on effective design processes of constructed wetlands

Decentralized wastewater treatment has become inevitable as conventional wastewater treatment plants involve huge construction and maintenance costs. One of the most popularly used decentralized wastewater treatments is constructed wetlands. Constructed wetlands are a cost-effective and sustainable treatment method for domestic and industrial wastewater. Over the years, there has been a lot of improvement in the design and process approaches of constructed wetlands. This review paper aims to find the impacts of design processes like artificial aeration, design and flow pattern, effluent recirculation, substrate media, vegetation, and C/N ratio on the treatment performance of constructed wetlands. Based on the review, it is found that intermittent aeration along with recirculation, hybrid constructed wetlands and baffled constructed wetlands are an effective way to remove ammonia and organics from wastewater. Phosphorous removal in constructed wetlands is highly dependent on substrates rather than wetland plants. Further, the paper discusses the future scopes and challenges in terms of improving the efficiency of constructed wetlands, reuse of industrial waste as substrate, solar energy based aeration, etc., to make constructed wetlands a sustainable wastewater treatment technology.