Constructed wetland for enhanced nitrogen removal of carbon limited wastewater and its economic and environmental assessment: A review

Abstract

Constructed wetlands (CWs) are regarded as a common method for the treatment of low carbon wastewater, yet their conventional application often results in ineffective performance. To enhance denitrification, several strategies are investigated in CWs for the treatment of carbon-limited wastewater. These strategies include the addition of external carbon sources such as plant-based materials and biodegradable synthetic polymers, embedment of biochar or autotrophic denitrification-based materials as the alternative fillings, and hybrid combination methods like multi-stage CWs and microbial fuel cell combined with CWs. This review comprehensively discusses the nitrogen removal performance, dominant functional microorganisms, and underlying mechanisms of these enhanced measures. Furthermore, a thorough environmental-economic assessment was provided, evaluating the cost-effectiveness and greenhouse gas (GHG) emissions of these strategies. By critically assessing the operational advantages and limitations of enhanced CW systems, this review presents strategic insights for the design and successful implementation of large-scale CWs in the treatment of carbon-limited wastewater.