A Small-scale Horizontal subsurface Flow constructed wetland for on-site treatment of Household wastewater in sub-tropical region in India

This paper presents the outcome of the study that investigates the performance of horizontal subsurface flow constructed wetlands (HSSF CWs) for the removal of pollutants in the treatment of household wastewater. Two identical beds were designed and installed, one bed “CW” was planted with locally available emergent macrophytes “Phragmites australis” and another bed “Control” was kept as unplanted. The substrate used in each bed was dual type (coarse gravel and fine gravel) as filter media. The beds were operated and monitored for six months at a constant flow rate of 200 L/day. Results showed a satisfactory performance in the removal of biological oxygen demand (BOD5: 82%), chemical oxygen demand (COD: 78%), total suspended solids (TSS: 79%), ammonium nitrogen (NH₄⁺-N: 74%), total nitrogen (TN: 54%) and total phosphorus (TP: 53%). The planted bed obtained a significantly higher reduction in pollutants than unplanted. The study shows that constructed wetlands technology is an excellent treatment option for household wastewater at small-scale.