Study on purification effects of nitrogen and phosphorus by constructed wetlands system in Xi'an

摘要

A research based on the constructed wetland system was conducted, to study its purifying effects for total nitrogen, total phosphorus and ammonia of Xi'an urban runoff under different Hydraulic Retention Time (HRT) and run-time interval cases, and then established the kinetic equations of three pollutants removal process, finally used design-expert software to build regression equations between hydraulic retention time, run-time interval and the removal rates. The results showed that the subsurface flow wetland could well remove nitrogen and phosphorus as well as other substances in runoff, its removal rates could reach 70%, and the better removal effect could be achieved when hydraulic retention time was in the range of 36 h~50 h and the run-time interval of 7 ds~10 ds; in addition, removal process of three pollutants all conform to the kinetic equation, the regression equations all have high correlation coefficients.