Full-scale performance of a vertical subsurface flow constructed wetland with a polyculture for greywater treatment

ABSTRACT Vertical subsurface flow constructed wetlands (VSSF) are a viable option for greywater (GW) treatment in decentralized areas. However, information on full-scale systems is limited. This work aims to evaluate the performance of a 6 m2 full-scale VSSF system with a polyculture for GW treatment. The physicochemical and microbiological characteristics of three GW sources (LGW, light greywater; DGW, dark greywater; and MGW, mixed greywater), system performance and polyculture development were evaluated. DGW represented the GW source with the highest level of contamination, with three- and seven-times higher COD (chemical oxygen demand) and TP (total phosphorus) than LGW, respectively. The VSSF achieved removal efficiencies of 42–85% for COD, 10–85% for TN (total nitrogen) and 31% for anionic surfactants. However, the VSSF achieved a removal efficiency of only 96% for E. coli. Typha latifolia performed best in polyculture, with relative abundance increasing from 10 to 54%, indicating its adaptability. Principal component analysis (PCA) confirmed that DGW is the main determinant of MGW characteristics and that LGW has a distinct compositional identity. These findings demonstrate the viability of full-scale VSSF for GW treatment. Adding steps for disinfection is recommended to improve the performance of VSSF for the safe reuse of water.