Evaluating the efficiency of Cyperus alternifolius on constructed wetland for the domestic wastewater treatment in the peri-urban area of Northern Vietnam

Abstract

Constructed wetland (CW) is an ecological work that can treat wastewater in natural condition. Combining CW with other ecological wastewater treatment works can create a suitable low-cost treatment system for peri- urban areas. The climatic conditions in the Northern region are favorable for the growth of Cyperus alternifolius, one of the commonly planted tree in HFCW worldwide. Our study focuses on the growth of Cyperus alternifolius on HFCW to evaluate the removal efficiency of organic substances and nutrients (BOD5, N-NH4, N-NO3, P-PO4). The dynamical coefficients of decomposition of those matters were also identified. This research employed a wastewater treatment pilot with HFCW planted Cyperus alternifolius and other ecological facilities in a peri-urban area in the North of Vietnam. It was found out that Cyperus alternifolius grew well with a high growth rate. The growth of Cyperus alternifolius enhanced the conversion of organic substances (BOD5) and nutrients (NH4, NO3, PO4) with high decomposition kinetic coefficients. The kinetic coefficient (kBOD) of HFCW in this research was 0.214md−1 which is much higher than the recommendation of Design Standard TCVN 7957:2008. Domestic wastewater after being treated through CW satisfied level A of National technical regulation on domestic wastewater QCVN 14:2008/BTNMT.