Performance intensification of constructed wetland technology: a sustainable solution for treatment of high strength industrial wastewater

The objectives of this study were to: (1) assess the intensification of chemical oxygen demand (COD) and phosphate (PO4-P) removal; and (2) generate a set of rate constants of COD degradation (k(COD)) and phosphate (k(PO4-P)) removal for the treatment of industrial wastewater (WW) using intensified adsorption beds. Two horizontal subsurface flow constructed wetlands (HSSFCWs) filled with coal ash and alum sludge and two conventional HSSFCWs packed with gravels were operated with different loadings of COD and PO4-P at a hydraulic retention time (HRT) of 24 hrs at water depth of 0.40 m. The bed performance was analysed for COD and PO4-P removal efficiency. The intensified HSSFCWs out-performed the control beds by a mean COD and PO4-P removal efficiency of 43 and 49%, respectively. The progression of COD and PO4-P removal along the system was fitted into the first order plug flow model (K-C model). In this study the k(COD) values ranged from 0.36 to 0.65 m/d with a mean of 0.46 +/- 0.08 m/d (n = 30) . The k(PO4-P) values ranged from 0.74 to 1.76 m/d and averaged to 1.23 +/- 0.37 m/d (n = 30), irrespective of the condition applied. Hence, these data can be used for future projects using HSSFCWs to treat industrial wastewater.