Correlation of the physiological resilience of <i>Phragmites australis</i> with contaminant removal efficiency in vertical-flow wetlands for greywater reuse

The effectiveness of constructed wetlands depends on the use of macrophytes for efficient greywater treatment and safe water reuse. Such wetlands are important in water-scarce regions, especially Jordan. This paper examined the physiological tolerance of Phragmites australis and its significance in removing contaminants in a vertical flow constructed wetland (VFCW) receiving institutional greywater. A bench-scale study was carried out using three experimental units: unplanted VFCW (VFCW1), planted VFCW with tap water irrigation (VFCW2) and planted VFCW with greywater irrigation (VFCW3). Removal percentages of chemical oxygen demand (COD(, biological oxygen demand (BOD5), and total suspended solids (TSS) in VFCW3 were 45.27%, 45.00% and 50.00%, respectively. Moreover, Escherichia coli (E. coli) removal percentage in VFCW3 was 85.13% with a final effluent concentration of 19.33 most probable number (MPN)/100 mL. The treatment process achieved Class A standards for COD and E. coli but was below requirements for turbidity and TSS. Improved contaminant removal is related to high proline production and nutrient uptake by Phragmites australis, which shows that plant physiological tolerance, is critical in increasing wetland efficiency and greywater reuse.