Journal of Environmental Chemical Engineering 10 (2022) 107444 Available online 22 February 2022 2213-3437/© 2022 Elsevier Ltd. All rights reserved. Nutrient pollution and its remediation using constructed wetlands: Insights into removal and recovery mechanisms, modifcations and sustainable aspects Tuhin Kamilya a , Abhradeep Majumder a , Manoj K. Yadav a , S. Ayoob b , Subhasish Tripathy c , Ashok K. Gupta d, * a School of Environmental Science and Engineering, Indian Institute of Technology, Kharagpur, Kharagpur 721302, India b APJ Abdul Kalam Technological University, Kerala 695016, India c Department of Geology & Geophysics, Indian Institute of Technology Kharagpur, Kharagpur 721302, India d Environmental Engineering Division, Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India A R T I C L E INFO Editor: V. Victor Keywords: Circular economy Hybridization Phytoextraction Removal mechanism System modifcations ABSTRACT Nutrient removal and recovery from nutrient-rich wastewater have recently gained signifcant attention because of their potential to contribute to sustainable development. Numerous treatment technologies have been implemented to tackle nutrient-rich wastewater, but high cost, low adaptability to varying organic loading, and undesirable effuent quality are a few factors that have signifcantly limited their applications. On the other hand, constructed wetlands (CWs) are robust, cost-effective processes with a high degree of nutrient removal and re- covery. In this review, the role of various biotic and abiotic components that affect the performance of CWs has been discussed. It was found that vertical fow CWs were more effcient in removing total phosphorus (64.6 ± 30%), while horizontal fow CWs were effcient in removing the total nitrogen (67.6 ± 20%). Furthermore, the introduction of artifcial aeration, external carbon sources, variation of plant species and substrate, and bio- augmentation signifcantly improved the performance of the CWs. Hybrid CWs have also been used to achieve enhanced total nitrogen removal and recovery (89%). However, phosphorus removal was not signifcantly affected by the hybridization of the CW-based systems. Hence, several recommendations have been suggested to enhance nutrient removal and recovery, such as incorporating hydrochar and oyster shells as substrate modi- fcations, providing suitable pre-treatment, and others. This review circumscribes the different aspects of ni- trogen and phosphorous recovery and removal from nutrient-rich wastewater treatment using CWs and may be instrumental in achieving a circular economy. 1. Introduction Water is one of the most important resources required to sustain human life. The primary sources of freshwater are rivers, lakes, and underground aquifers. However, almost one-third of the global popu- lation does not have access to clean water [1]. The quantity and quality of freshwater resources have depleted due to the over-exploitation of groundwater, population growth, urbanization, and industrialization [2, 3]. Hence, activities such as rainwater harvesting, desalination of seawater, reuse of treated industrial, municipal, and agricultural wastewater, and others are essential to promote water sustainability [4–6]. The concept of reuse of treated wastewater and resource recovery from wastewater is a good option for water management, considering the legislation requirements and the circular economy (CE) principles [7,8]. However, the constant deterioration of wastewater quality and stringent reuse or discharge standards have made reusing wastewater challenging [9]. In general, wastewater from fertilizer industries, agricultural run-off, domestic household, commercial establishments, and others contain a signifcant amount of nitrogen and phosphorous along with other organic and inorganic pollutants. Nitrogen and phosphorous fnd their way into wastewater through over-fertilization, thereby resulting in nonpoint source pollution, groundwater contamination, and other environmental issues [10]. Various anthropogenic and natural activities * Corresponding author. E-mail address: agupta@civil.iitkgp.ac.in (A.K. Gupta). Contents lists available at ScienceDirect Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece https://doi.org/10.1016/j.jece.2022.107444 Received 19 December 2021; Received in revised form 13 February 2022; Accepted 19 February 2022