Wastewater nutrients and coliforms removals in tidal flow constructed wetland: Effect of the plant (Typha) stand and biochar addition

Constructed wetlands (CWs) could be a sustainable approach to address the issue of low-cost treatment of domestic wastewaters in rural and sub-urban areas. The present study compiles the results of a mesoscale study of tidal flow constructed wetlands (TF-CWs) with biochar (BC) incorporation and Typha plantation (P). The decision appeared to be decent for treating wastewater or various parameters like biochemical oxygen demand (BOD), nitrate (NO3-N), sulphate (SO4- 2), chemical oxygen demand (COD), phosphate (PO4- 3), and coliforms in TF-CW with tidal flow mode with effluent recirculation. Three setups of TF-CW (SB: substrate + BC ; SBP: substrate + BC + P; and SP: a substrate + P) operated for 216 h and changes in studied parameters were recorded. The enhanced results were obtained for the maximum removal of COD, BOD, NH4+-N, NO3-N, PO4-, SO4- 2 and coliforms (94.77, 96.07, 85.65, 64.05, 71.69, 77.61 and 97.27%, respectively) in SBP followed by, SP and SB. Presence of carbon source in support matrix could enhance microbial activities, providing extra adsorptive surface, and oxygen retention which could be advantageous for TF-CWs. Thus the study suggests that TF-CWs with effluent re-circulation and BC addition in the substratum can be an effective strategy to operate a CW effectively in remote areas for domestic and rural wastewater treatment with low energy input.