Phytoremediation of Secondary Treated Sewage through Constructed Wetland: Lab-Scale Study

Due to increasing urbanization and industrialization, India freshwater resources are deteriorating. Discharge of untreated wastewater into the aquatic ecosystems is the major source of pollution to these ecosystem. Conventional methods of treatment of the wastewater are quite costly, energy-intensive and require huge investment while natural systems such as Constructed Wetlands (CW) can be a better option for the treatment of wastewater. Under the present study laboratory scale Vertical Flow Constructed Wetland (VFCW) was utilized for the further treatment of secondary treated effluent collected from the MBBR (Moving bed biofilm reactor) based sewage treatment plants (STPs). The lab scale VFCWs were planted with Typha latifolia and Canna indica plants and filled with gravel and sand which act as growth and filter medium. Experiments have been performed to evaluate the performance of VFCW at different retention times (RT) in hours (h) i.e., 0 h, 24 h, 48 h, and 72 h. The secondary treated sewage was supplied to the VFCW and a change in the physicochemical properties of the sewage with increasing time was measured. There was continuous decrease in the major parameters of the secondary treated sewage in 72 h of incubation period thereafter a little or no change was observed. The removal efficiency for biological oxygen demands (BOD), chemical oxygen demands (COD), nitrate also phosphate was more after 72 h through VFCW planted with Typha than with Canna. The VFCW planted with Typha also showed greater performance than VFCW planted with Canna. The removal efficiency of VFCW for unplanted (control) system wase less than the planted system.