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In this study, an artificial wetland filler matrix capable of effectively fixing phosphorus was prepared using a non-combustion process to save energy. To evaluate the adsorption performance of this filler, adsorption experiments were performed and the phosphorus adsorption mechanism characterization was studied. An alkaline environment was found to be conducive to the increase of adsorption capacity, but excessive alkalinity was not conducive to adsorption. Static adsorption experiments showed that the phosphorus removal rate could reach 95% in the simulated phosphorus-containing wastewater after adsorption completion. The adsorption process is closely simulated by the pseudo-second-kinetic adsorption model. The isothermal adsorption experiment data were consistent with the Langmuir and the Freundlich adsorption isotherms. The characterization results showed a large number of micropores and adsorption binding sites inside and on the surface of the filler. Speciation analysis on the adsorbed phosphorus revealed that chemisorption by calcium in this filler was the dominant adsorption mechanism. The research results of this study provide the basis and reference for the development of high-efficiency phosphorus removal filler in constructed wetlands. [ABSTRACT FROM AUTHOR]

Aquatic plants easily wither and go into dormancy in winter when temperature is extremely low. Little is known about nitrogen and phosphorus uptake by plants and its role in removing nutrient in constructed wetlands (CWs). Investigating the performance of CWs planted with overwintering plants and selecting out which plants will support an effective CW over the winter period are important. In this study, microcosmic subsurface vertical flow constructed wetlands (MVFCWs) were planted with Iris sibirica for treating simulated polluted river water and evaluated for nutrient removal, plant growth characteristics and plant nutrient uptake under different nutrient concentrations. Treatment performances indicated that the highest average total nitrogen (TN), ammonia nitrogen (NH4+-N), total phosphorus (TP), soluble reactive phosphorus (SRP), and chemical oxygen demand (COD) removal efficiencies were obtained in MVFCW units with medium nutrient (10-16 mg/L TN, 7-10 mg/L NH4+-N, 1.8-2.5 mg/L TP, and 80-120 mg/L COD); the removal efficiencies were 45.8 ± 15.4%, 62.1 ± 8.8%, 57.7 ± 8.3%, 59.1 ± 10.1%, and 39.3 ± 12.1%, respectively. MVFCW units with low nutrient (5-8 mg/L TN, 3.5-5 mg/L NH4+-N, 0.9-1.25 mg/L TP, and 40-60 mg/L COD) exhibited the worst treatment effects. Plant nutrient uptake in the different MVFCW units ranged from 19.86% to 50.19% of N removal and from 13.19% to 22.32% of P removal at the end of experiment. The N and P accumulation ability of the below-ground part of plants was better than that of the above-ground part. The I. sibirica plants demonstrated high nutrient uptake in winter, and MVFCWs facilitated a certain degree of nutrient removal. Thus, I. sibirica can be considered an effective overwintering plant selection in CWs for restoring polluted river water and potentially be suitable for generalizing elsewhere, especially over the winter period. [ABSTRACT FROM AUTHOR]