Treatment Of Municipal Wastewater Using Nature-Based Constructed Wetlands: Role of Plant Species and Media in Heavy Metal and Nutrient Removal

The growing population and wastewater generation in cities are a major challenge for municipal wastewater treatment, especially for the developing areas where centralized treatment plants are not fully equipped or are not available. Constructed wetlands are a feasible and economically sound solution as they can be effectively operated and efficiently utilize natural wastewater treatment processes. The present study investigated the performance of horizontal subsurface wetlands using different plant species and media combinations for removal of nutrients and heavy metals from municipal wastewater. Three new water treatment systems were developed where sand, gravel, biochar and wetland plants are used, Phragmites australis and Typha latifolia. The water quality was measured prior to, during and after the treatment. The results showed a significant decrease in pollutant removal with vegetation and biochar-based media. The system comprised sand, gravel, biochar and Typha latifolia had the highest treatment efficiency (more than 80% removal of nutrients and more than 84% removal of heavy metals) with sand, gravel, biochar and Typha latifolia. Adsorption, microbial activity and root zone interaction, and phytoremediation were all associated with improved treatment efficiency as the results were demonstrated to be more effective in this study. The findings demonstrate that well designed wetlands can be developed into a highly decentralized wastewater treatment system and promote sustainable water management with a green wastewater treatment solution in nature-based treatment systems. The study also provides a perspective to the selection of plant species and media for better nutrient and heavy metal removal in nature-based treatment systems.