Decentralized greywater treatment for nonpotable reuse in a vertical flow constructed wetland

Abstract

Reuse of domestic greywater (GW) is emerging as an important approach to the management and conservation of water resources, particularly in rural and developing areas where small-scale decentralized treatments are suited. Vertical flow constructed wetlands have been increasingly used as a sustainable technology for the ecological treatment of wastewater. In this paper, an attempt has been made to investigate the potential of greywater treatment for nonpotable reuse in a subsurface vertical flow constructed wetland (CW) planted with Chrysopogon zizanioides (Vetiver grass) and also to compare the system with a vertical flow constructed wetland planted with Cymbopogon flexuosus (Lemon grass). Raw and treated effluents were sampled periodically and analysed for a variety of water quality parameters such as pH, Turbidity, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Nitrates and Phosphates. The results indicated good removal efficiency for the CW system planted with Chrysopogon zizaniodes when compared to the CW system planted with Cymbopogon flexuosus. The best removal efficiencies observed were: Turbidity (98%), TSS (80%), COD (79%), BOD (87%), nitrates (71%) and phosphates (52%). The constructed wetland proved to be a robust and reliable decentralized system for the treatment of GW for nonpotable reuse.