Performance of Constructed Wetland for the Treatment of Pulp and Paper Mill Wastewater

Constructed wetlands (CWs) have a great potential for the treatment of wastewater. This study evaluates the performance of horizontal subsurface flow constructed wetland (HSSF-CW) for the treatment of pulp and paper mill wastewater over a period of 2 months. The dimensions of the treatment system were 3.5m x 1.5m x 0.28m with surface area of 5.25 m2, filled with fine sand and gravel. The unit was planted with an ornamental plant species Canna indica. The treatment performance of the system under two different hydraulic retention time (HRT), 5.9 and 8.6 days, was assessed. Removal efficiencies for chemical oxygen demand (COD) and color were in the range of 81–94% and 95–99% respectively. A linear correlation between COD mass loading and mass removal was obtained. The main removal processes were physical filtration and microbial interactions that took place in root zone. Evapotranspiration (ET) of the treatment system was also determined for water budget studies.