Design parameters and electrical conductivity shape dissolved organic matter aromaticity in full-scale constructed...

Area of Science:

• Environmental Science
• Water Chemistry
• Ecology

Background:

• Constructed wetlands (CWs) are crucial for wastewater treatment, influencing downstream aquatic ecosystems by altering dissolved organic matter (DOM).
• Understanding DOM variations and their controlling factors in full-scale CWs is essential for predicting ecological impacts.
• Current knowledge on DOM dynamics within CWs remains limited.

Purpose of the Study:

• To investigate changes in DOM characteristics within full-scale CWs.
• To identify key factors influencing DOM alterations.
• To assess the ecological implications of CW-modified DOM.

Main Methods:

• Field survey of 57 sites across 14 full-scale CWs in Shandong, China.
• Laboratory experiments to complement field observations.
• Statistical modeling to determine factors affecting DOM shifts.

Main Results:

• CWs shifted DOM towards greater aromaticity and hydrophobicity, reducing low molecular weight neutrals (LN).
• Plant density (PD), electrical conductivity (EC), and light conditions (LC) were dominant factors influencing DOM characteristics.
• Direct and indirect associations (microbial) were observed, with LC showing opposing effects.

Conclusions:

• CWs modify DOM, reducing labile components but potentially increasing risks associated with aromatic compounds.
• Plant density, electrical conductivity, and light conditions are critical design parameters for CWs.
• Optimizing CW design based on influent characteristics is necessary to balance treatment efficiency and ecological risks.