Removal of Nutrients from Saline Waste Sewage with Different Vertical-Flow Constructed Wetland Substrates

Abstract

In order to find the best substrates of constructed wetlands for saline waste sewage treatment, Bio-ceramic, quartz sand, zeolite and medical stone were used as filtering media for saline sewage treatment with proper proportion microbe, isolated from the sewage of the Wuqing sewage treatment plant. In this paper, the purification of the vertical-flow constructed wetlands (VFCWs) with different substrates was studied, and the component of the nitrogen in the influent and effluent was analyzed. The concentrations of chemical oxygen demand (COD), ammonia (NH4+-N), total phosphorus (TP), total nitrogen (TN) and the salinity of the influent during the experimental period were 150mg•L-1, 36 mg•L-1, 8mg•L-1, 36mg•L-1and 1.6%. Under the condition that the hydraulic loading rate was 0.25m•d-1, the average removal efficiency of COD, TP and TN were obtained about 68.81%, 32.01% and 20.72 %, respectively with Bio-ceramic; 61.92%, 31.75% and 34.33%, respectively with quartz sands; 69.47%, 35.44% and 55.28% , respectively with zeolite; and 64.77%, 32.63% and 34.72%, respectively with medical stone. This result proves that comprehensive purification of the system with zeolite is the best.