Removal Efficiency of Physicochemical and Microbial Pollutants in Wastewater Using Vertical Flow Constructed Wetlands

Abstract Constructed wetlands are decentralized systems for treating wastewater (WW), yet there is still a wide knowledge gap regarding the potential of some indigenous macrophytes. In this study, two indigenous macrophytes, Eragrostis curvula (EC) and Paspalum dilatatum (PD), were evaluated for treating municipal wastewater using Vertical Flow Constructed Wetland (VFCW) with shea nut shell biochar (BCH) as a substrate enhancer. EC was represented by two units (ECWW and ECBCH), while PDWW and PDBCH represented the wetlands planted with PD. A hydraulic retention time (HRT) of 5 days was observed with a hydraulic loading rate (HLR) of 24 mm/day. The highest removal efficiencies for physicochemical and microbial parameters were as follows: Total Suspended Solids (TSS) – 94.93±8.43%, Total Dissolved Solids (TDS) – 37.68±16.17%, Turbidity – 100±2.47%, Salinity – 60.39±7.86%, Oxidation-Reduction Potential (ORP) – 91.81±13.96%, Electrical Conductivity (EC) – 41.75±7.17%, Nitrite (NO 2 -N) – 100±26.78%, Nitrate (NO 3 -N) – 100±0%, Ammonium (NH 4 -N) – 92.17±4.78%, Faecal Coliform (FC) – 100±9.03%, and Total Coliform (TC) – 98.71±13.55%. Plant height and number of leaves showed that EC was better established than PD. The HYDRUS-1D software was used to validate the porous media parameters and it was concluded that the retention capacities of the constructed wetlands were optimal, with flow occurring from the residual water content region to saturated water content region. The measured shape factors α (0.438m- 1 ), θ (1.0) and n (2.063) produced a Python-fitted curve comparable to the validation curve obtained from the HYDRUS-1D model.