Performance of a single-reactor vertical flow constructed wetland for nitrogen removal via the CANON process

Khajah, Mishari, Babatunde, Akintunde O., Al-Haddad, Sara and Webster, Gordon ORCID: https://orcid.org/0000-0002-9530-7835 2026. Performance of a single-reactor vertical flow constructed wetland for nitrogen removal via the CANON process. Kuwait Journal of Science 53 (4) , 100640. 10.1016/j.kjs.2026.100640

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Abstract

A single-reactor vertical flow constructed wetland (VFCW) was designed to treat synthetic domestic wastewater after secondary treatment using the Completely Autotrophic Nitrogen Removal Over Nitrite (CANON) process. This study investigated the effectiveness of the CANON process under varying recirculation numbers (Rn) and influent inorganic carbon (IC) concentrations to optimize nitrogen removal. A tidal flow strategy was applied, featuring a short unsaturated phase to promote partial nitrification and a prolonged saturated phase to sustain anammox activity. Over a period of 330 days, nitrogen removal rates reached 5.9, 6.4, and 6.5 gN/m3/d at an Rn of 6, 4, and 3 times per day, respectively, with IC at 150 mg/L. At Rn = 6, removal rates of 5.6, 5.7, and 6.1 gN/m3/d were obtained with IC concentrations of 100, 200, and 300 mg/L, respectively. Ammonium removal efficiencies ranged from 86.7% to 99.3%, while total nitrogen removal varied between 64.1% and 74.8%. Statistical analysis indicated that both Rn and IC had a significant effect on nitrogen removal performance, with optimal performance observed at Rn = 3 with 150 mg/L IC and at Rn = 6 with 300 mg/L IC. Microbial analysis revealed dominant phyla including Pseudomonadota, Acidobacteriota, Planctomycetota, Chloroflexota, and Nitrospirota, with greater diversity detected at the upper sampling point. Potential nitrifying bacteria, including anammox groups, Nitrosospira, Nitrosomonadaceae, and Nitrospira, were prevalent throughout the system, while denitrifiers such as Thauera, Azoarcus, and Zoogloea were enriched in the lower sampling point. These results demonstrate that adjusting Rn and IC supply in tidal flow VFCWs can effectively promote the CANON process and achieve sustainable nitrogen removal.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Pharmacy
Publisher:	Elsevier BV
ISSN:	2307-4108
Date of First Compliant Deposit:	27 July 2026
Date of Acceptance:	16 July 2026
Last Modified:	05 Aug 2026 14:33
URI:	https://orca.cardiff.ac.uk/id/eprint/188464

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