Performance of continuous pilot subsurface constructed wetland using Scirpus grossus for removal of COD, colour and suspended solid in recycled pulp and paper effluent

Pulp and paper mill industry is already known as an extensive water user and hence produces large volume of wastewater. Phytoremediation has merits to offer due to its environmentally friendly, relatively low cost and easy maintenance. This work focused on the performance of a continuous pilot subsurface flow (SSF) system of constructed wetlands in removing chemical oxygen demand (COD) representing organic carbon, colour and suspended solids from recycled pulp and paper mill under 5-day hydraulic retention time (HRT) for 95 days. In this study, there were two tanks based on the SSF system; one tank planted with Malaysian native bulrush (Scirpus grossus) and another tank without plants acting as a control. It was found that the SSF system with S. grossus was much better compared to the SSF control. Throughout the 95-day exposure, the planted SSF system have achieved removals of 66.1, 55.8 and 87.2% for COD, colour and suspended solid (SS), respectively. However, the control SSF system without plants has lower performance for all the three parameters (62.4% COD, 44.4% colour and 84.8% SS), giving evidence that constructed wetlands is an efficient technology to phytoremediate COD, colour and SS from recycled pulp and paper effluent.