Performance Evaluation of Two-Stage Vertical Flow Multispecies Constructed Wetland for Domestic Wastewater Treatment

Abstract

Decentralized treatment of domestic wastewater with the use of constructed wetland (CW) as physical and biological treatment is widely used. The performance of CW can be enhanced by using multispecies and dual support medium. In this context, a laboratory-scale treatment system consisting of a settling tank followed by two-stage vertical flow multispecies constructed wetland (VFMCW) was developed. The reactors of VFMCW connected in series were planted with Canna India and Phragmites Karka in charcoal and grit as support medium. The system was operated in continuous fill and drain mode for various hydraulic loading rate (HLR) which corresponds to hydraulic retention time (HRT) of 1.50–12 h for each stage and overall system. The feed used for system was wastewater collected from sump which is contributed by greywater and blackwater from hostel in the college (Walchand College of Engineering, Sangli) premises. The performance of the system was evaluated for organic matter (measured in terms COD) removal. Dissolved oxygen (DO) enhancement in the system was also assessed. The COD removal efficiency was found to be 53–80% for the HLR varied from 60 to 7.5 mm/h. Both the stages of VFMCW contributed significantly to DO in effluent for all HLRs.