Parameter estimation of pollutant removal for subsurface horizontal flow constructed wetlands treating greywater

Abstract

Treatment efficiencies of pilot scale constructed wetland treating greywater from a staff canteen of the University of Moratuwa was studied to estimate the temperature dependent reaction rate constants of specific pollutant removal mechanisms. The treatment cell, constructed below the ground level is four meter (4.0 m) long 1.8 m wide (at the top level). The cell is divided longitudinally at the centre while vertical baffles are provided at approximately 590 mm intervals, running through the entire vertical depth (0.75 m) of the wetland cell with an opening of 270 - 380 mm. Considering the middle separation, the effective average width and the length of the treatment cell is 0.75 m and 8.0 m, respectively. The bed is vegetated with cat tail (Typha Latifolia) planted at approximately 0.75 m intervals. The study estimates the design parameters pertaining to local conditions to optimize the design considerations and sizing requirements using both first order and Monod type models. The estimated parameters can effectively be applied in sizing constructed wetlands in tropical climatic conditions. The results show that the surface area of SHF CWs can be reduced by 26% by utilizing the newly estimated parameters from the current study.