Studies on effects of soil enzymes for removal of nitrogen and phosphorus from sewage water treatment by constructed wetlands

Abstract

Continuous application of sewage water to agricultural land can pose a serious threats to surface and ground water. Constructed wetlands (CWs) are becoming increasingly a major option worldwide for removing contaminants from domestic wastewater. One of the biological processes in CW is enzyme activity which plays a major role in releasing nutrients from organic substances. In this study, the enzyme activities and their relation to removal of nitrogen and phosphorus were investigated under three different vertical flow wetlands namely Canna indica, Typha angustifolia and Xanthosoma sagitifolium with hydraulic laoding rate of 0.00516cm/day. The activities of enzymes (Urease, Dehydrogenase and Phosphatase) were higher in planted system than unplanted system. Urease and dehydrogenase activity were significantly related with removal of Total nitrogen and phosphatase were significantly related with removal of Total phosphorus. This results suggests that increasing enzyme activity may increase nitrogen and phosphorous removal. Therefore this study concluded that the activity of urease in the root zones could be an important indicator for N purification in wastewaters.