Nitrogen retention and purification efficiency study for typical wetlands in West Jilin: effects based on microcosm experiment and phosphorus increase.

摘要

The indoor simulated experiment is applied to study the process of removing the total nitrogen (TN), NH₄-N, and NO₃-N from sewage through the typical wetland units in West Jilin, as well as to investigate the effects of the phosphorus increase on nitrogen removal process in different wetland units. As a result, the four wetland units, namely Typha orientalis Presl., Phragmites australis, Softstem bulrush, and Scirpus triqueter L., have relatively better retention and purification effects, with a nitrogen removal rate of above 95%. The removal process of nitrogen represents the negative exponent curve among the four wetland types. Moreover, the nitrogen concentration in the sewage is rapidly reduced in the beginning stage of the experiment and later tends toward stability. The rate of nitrogen removal is highest for the Phragmites australis wetland unit. Meanwhile, the phosphorus importation has different effects on the nitrogen removal rate in different wetland units. The removal rates of TN, NH₄-N, and NO₃-N were improved for the Typha orientalis Presl. and Softstem bulrush wetland units as the phosphorus content increased, whereas the removal rates were restrained in the Phragmites australis unit and reduced in the Scirpus triqueter L. unit under the same conditions.