Characterization of dissolved organic matter and carbon release from wetland plants for enhanced nitrogen removal in constructed wetlands for low C-N wastewater treatment.

The effects of pretreatment methods on the structure of functional groups and denitrification promotion capacity of solid carbon sources derived from reeds and cattails were elucidated. Alkaline treatment improved the relative content of carbon in the plant tissues, as well as prolonged the high denitrification rate of 0.40 mg/(L·h) from 6 days up to circa 28 days. Moreover, alkaline-heated cattails (ALH-C) showed high denitrification promotion capacity, and increased the removal rate of TN, NO3--N and NH4+-N in the CW by 24.41%, 31.80% and 8.80%, respectively. Furthermore, the quantity, quality and migration of dissolved organic matter (DOM) released from ALH-C in CW analyzed via fluorescence excitation-emission matrix spectrophotometry showed mainly humic acid-like, tyrosine-like, and tryptophan-like components. These DOM components were highly bioavailable and had minimal effects on COD removal. These results provide insights into the preparation and environmental applications of plant carbon sources.