In-depth performance evaluation of an innovative halophyte-based multistage constructed wetland- microbial fuel cell for the treatment of brackish sewage

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 498; p. 155262
• Main Authors: Verma, Palindhi, Rajgor, Dipak, Satasiya, Gopi, Ray, Sanak
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-10-2024
• Subjects: Desalination; Electroactive wetland; Emerging contaminants; Green energy; Halophytes; Kinetics; Green energy; Electroactive wetland; Kinetics; Halophytes; Desalination; Emerging contaminants
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.155262

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•Integration of electrodes in CW improved brackish sewage treatment performance.•Electric circuit alleviated salt stress in J. ridigus and improved plant growth.•Electrodes promoted microbial activity in MEBS.•Voltage generation correlated with COD concentration.•Halophyte-based MEBS is well suited for treating brackish sewage in coastal regions.
Constructed wetland-microbial fuel cells (CW-MFC) can be the future of sustainable wastewater management. This study developed a multistage CW-MFC based on the halophyte Juncus ridigus for treating brackish sewage. Its treatment efficiency was compared with a multistage constructed wetland without electrodes (CW) and a control (C), which had neither electrodes nor plants. The CW-MFC showed significantly higher removal efficiency for COD, BOD, PO43--P, NH4+-N, NO2–-N, and NO3–-N, with removal efficiency of 81 %, 88 %, 83.58 %, 90.75 %, 80.96 %, and 78.75 %, respectively. Up to a 40.6 % decrease in salinity was observed in CW-MFC, followed by CW and C. Plant absorption and electrode adsorption were the primary mechanisms for removing major salt-contributing ions and elements like Cl-, SO42-, Na, Mg, and Ca. It was further confirmed by their increased deposits in plant tissues and electrodes, as revealed by SEM-EDX. A second-order kinetic model was used to investigate the efficiency of the CW-MFC system regarding pollutant removal. CW-MFC efficiently removed several emerging contaminants from sewage, including phenol, 3,5-bis(1,1-dimethyl ethyl)-, which was also found to be accumulated in the shoots of J. ridigus. Plants in CW experienced stress, as evidenced by lower biomass (47.47 % lower than CW-MFC) and decreased chlorophyll content (20 %), whereas in CW-MFC, they were extremely healthy. Interestingly, CW-MFC had a higher bacterial population than CW, which indicates increased microbial activity. CW-MFC was found to be the most efficient treatment system as it alleviated plant stress and increased bioaccumulation and microbial activity for treating brackish sewage.