Performance of horizontal subsurface flow constructed wetland in the removal of Tannins
Canadian Journal of Civil Engineering
Department of Chemical and Process Engineering, University of Dar es Salaam, P.O. Box 35131, Dar es Salaam, Tanzania
A horizontal subsurface flow constructed wetland (HSSFCW) was employed to remove tannins from the effluent of a tannins extracting company. Two HSSFCW cells with hydraulic retention time (HRT) of 9 d and packed with limestone were used. One cell without macrophytes was used as a control, while the second cell was planted with Phragmites mauritianus. Results indicated that HSSFCW was capable of treating tannin wastewater that has been seeded with primary facultative pond sludge. Tannins and chemical oxygen demand (COD) removal efficiency of 95.9% and 90.6% with outlet concentration of 27 mg/L and 86 mg/L, respectively, were obtained in the planted cell; while the tannins and COD removal efficiency of 91.1% and 89.5% with outlet concentration of 57 mg/L and 96 mg/L, respectively, were obtained in the control cell.
Chemical oxygen demand removals; COD removal efficiency; Constructed wetlands; Control-cell; Horizontal subsurface flow constructed wetlands; Hydraulic retention time; Macrophytes; Outlet concentration; Performance; Phragmites; Primary facultative ponds; Agriculture; Biodegradation; Biological water treatment; Degradation; Effluents; Microbiology; Oxygen; Removal; Roads and streets; Wastewater; Wastewater treatment; Wetlands; Chemical oxygen demand; biodegradation; chemical oxygen demand; concentration (composition); constructed wetland; limestone; performance assessment; pollutant removal; subsurface flow; tannin; waste treatment; Phragmites mauritianus