Nitrogen Removal from Three-stage Oxidation-reduction System by Simulation of the Riparian Environment

Abstract

Riparian zones (RZ) is area in which sediments typically exhibit strong redox transitions and play a key role in river metabolism. A three-stage oxidation-reduction cores device which perfuse with heterogeneous sediment (gravel and sand) was used in the present study to analyze nitrogen removal in the multiple oxidation-reduction environment of river. The monitoring of oxidation-reduction potential (ORP) on the device confirmed that the system was successfully reproduced three-stage oxidation-reduction gradient environment in riparian zones. The results indicated that ammonia nitrogen, nitrate nitrogen, total nitrogen (TN) and chemical oxygen demand (COD) can be removed effectively, and the removal rates are 72.05%, 99.28%, 78.17% and 77.64% respectively. And optimum removal efficiency of nitrogen was founded in the first-stage downflow column. The ratio of C/N and ammonia nitrogen load of influent influence the nitrogen removal effect, and maximum removal rate of nitrogen was observed under the condition that C/N is 8 and ammonia nitrogen load is 2.63g d-1 m-3.