Pilot-scale horizontal subsurface flow constructed wetland for removal of chromium from tannery waste water with suitable local substrate material

Abstract

The aim of this study was to investigate the performance of pilot scale horizontal subsurface flow constructed wetlands (HSSFCW) for removal chromium containing industrial wastewater with locally available two plant species (Cyprus Papyrus) and Para grass (Brachiara mutica). Twenty-one constructed wetland systems half-filled with coarse aggregate were built. Eighteen of them were used to study the efficiency of chromium (VI) removal with both plants in three replicates and the other three units were used as a control. The experiments were performed at different bed depth of 0.20 m, 0.40 m, and 0.60 m. It was found that HSSFCW with papyrus at constructed wetland bed depth of 0.20 m was the best performed for chromium removal with an efficiency of 98.41%. Comparing efficiency for chromium (VI) removal at the same bed depth, papyrus plant was better than Para grass. On one hand, the growth rate of the plant species was unaffected by the depth of the constructed wetland wastewater system.