Abstract

Constructed wetlands (CWs) are being increasingly considered for the treatment of greywater (GW) from commercial laundry sources. However, limited information is available on how operational and design parameters influence CW performance. This study aimed to evaluate the performance of vertical subsurface flow constructed wetlands (VSSFCWs) for the treatment of commercial laundry GW with a focus on the effects of design and operational parameters. The operation of two lab-scale VSSFCWs was divided into three stages, during which ORLs progressively increased and HRTs decreased. One VSSFCW was filled with zeolite (Zeo), while the other used gravel (Gra). In Stage III, both systems achieved removal efficiencies of 73-86 % for chemical oxygen demand (COD), 72-84 % for ammonium-nitrogen (NH4+-N), and 68-89 % for phosphate-phosphorus (PO43--P), indicating a significant improvement (p < 0.05) as OLR increased from 12.3 to 49.9 gCOD/m(2)d and HRT decreased from 10 to 3.5 days. In all stages, the Zeo system outperformed Gra by 19-33 % in terms of organic matter and nutrient removal (p < 0.05). Additionally, the Freundlich isotherm model revealed a reduction in the sorption capacity of the used zeolite to 0.004 mg/g, which was 1 to 5 times lower than the control zeolite. These findings emphasize the importance of optimizing operational parameters and selecting appropriate support media for the effective and sustainable reuse of commercial laundry GW.