Work

Effects of polyculture on nutrient removal from residential raw sewage using field-scale artificial floating islands

Year: 2025

Type: article

Abstract: Nutrient pollution poses a significant challenge to global water bodies, particularly from non-point sources due to their diffuse nature. This study investigated the effectiveness of Artificial Floating Islands (AFIs) as a phytoremediation technology to address this issue. We constructed and monitored a field-scale AFI system in the equalization basin of a wastewater treatment plant for preliminary treatment of residential raw sewage. Focusing on a polyculture of two native aquatic plants - Carex comosa (bristly sedge) and Eleocharis obtusa (blunt spike-rush) - we assessed how polyculture influenced nutrient assimilation and evaluated the overall performance of polyculture AFI systems under natural conditions. Our results showed that polyculture simultaneously affected plants’ capacity of nutrient assimilation and biomass production. The potential competition within the polyculture systems promoted the growth of C. comosa while suppressing E. obtusa . The enhanced nutrient assimilation in C. comosa plant tissues was mainly attributed to its increased biomass production. Additionally, we observed a negative correlation between pH and the storage of total oxidized nitrogen (NO 2 − + NO 3 − ), ammonium (NH 4 + ), and orthophosphate (PO 4 3− ), with the highest nutrient storage occurring at a near-neutral pH of 7.5. Environmental factors such as pH and water temperature interacted with the effects of polyculture on nutrient assimilation, with C. comosa in polyculture systems showing the highest sensitivity to these factors. Throughout the study, polyculture AFIs exhibited the highest nutrient assimilation, with peak values of 2968 mg/m 2 for NH 4 + , 1767 mg/m 2 for PO 4 3− , and 12 mg/m 2 for NO 2 − + NO 3 − , outperforming the two monoculture AFIs. Notably, nutrient assimilation in polyculture AFI systems did not average the performance of monoculture systems but demonstrated higher values and greater robustness under varying environmental conditions. These findings highlight the potential of using polyculture to extend the operational lifespan, enhance performance, and reduce the constructional costs of field-scale AFI systems for managing nutrient pollution. • C. comosa showed competitive advantages over E. obtusa within polyculture systems. • Polyculture improved nutrient assimilation within C. comosa plant tissues. • Improved biomass production did not translate to grater nutrient assimilation. • PH and temperature interactively influenced the performance of polyculture AFIs. • Polyculture AFIs showed higher nutrient assimilation and greater robustness.

Source: Journal of Environmental Management

DOI: 10.1016/j.jenvman.2025.124562

Authors: Zhaozhe Chen, Audrey H. Sawyer, Jiyoung Lee, Ozeas S. Costa

Institution: The Ohio State University

Language: English

Topic: Constructed Wetlands for Wastewater Treatment

Subfield: Waste Management and Disposal

Field: Environmental Science

Domain: Physical Sciences

SDGs: Clean water and sanitation, Responsible consumption and production, Zero hunger

Open Access status: hybrid

Estimated APC paid: $3,750