Study the accumulation of nutrients and heavy metals in soil media in sub-surface flow (SSF) constructed wetland

Abstract

This study focus on the accumulation of heavy metals (Fe, Zn, Mn and Ni) and nutrients (PO4 3- and NH3-N) in the soil media of the sub surface flow constructed wetland. This study was conducted by a lab-scale sub surface flow constructed wetland with two different reactor namely planted and control. This system consists of a feeding tank, wetland reactor and settling tank. The soil media comprises of soil and gravel. Wetland plant is Limnocharis flava. The SSF reactor is arranged in series and operated with different hydraulic loading rates (HLR) which are 0.55 m/d and 0.39 m/d for 24 hours hydraulic retention time (HRT). The plants, leachate and media were removed and replaced with new plants, leachate and media for each HLR. The leachate wastewater was continuously pumped daily into SSF reactor directly from the leachate storage tank by gravity flow. Accumulation of heavy metals and nutrients was measured at different depth of the soil media which is top, middle and bottom. The result shows that, Fe and PO4 3- give the highest accumulation of heavy metals and nutrients in the soil media.