人工湿地对二级出水中TN、TP去除效果的季节性研究

研究了垂直流和表面流两种人工湿地系统在水力停留时间为2 d条件下,在不同季节对二级出水中TN、TP的去除效果。结果显示,垂直流湿地系统对TN、TP的去除效果优于表面流湿地系统。两种类型的人工湿地对TN的去除效果随季节的变化而波动,夏秋季节去除率最高,春季次之,冬季去除效果最差;垂直流人工湿地系统对TP的去除效果随季节的变化趋势与TN去除率的变化相同,而表面流湿地系统对TP的去除效果在春夏秋季变化不大,冬季的平均去除率仅有16.5%。分析认为,人工湿地应用于二级出水的深度处理,对于满足观赏性景观环境用水(尤其是观赏性河道和湖泊类)的水质指标是可行的。

Seasonal effects of the artificial wetlands on the removing of nitrogen and phosphorus content in secondary effluent

The present paper is intended to study the seasonal effect of the artificial wetlands on the removal of nitrogen and phosphorus ingredients in the secondary effluent Acorus gramineus Soland,Phragmites australis and Cyperus alternifolius.While the Phragmites australis and Cyperus alternifolius were artificially buried deep in 0.3 m media in vertical flow wetland and rooted in 0.15 m media in the surface flow wetland,the media were composed of gravel of 1 cm in diameter,the two systems can be built in concrete ponds deep in 0.5 m×3.0 m,whose bottom gradient accounts for 1%.Such artificially constructed wetlands can be used to purify the secondary effluent from a university sewage-treating plant. In proceeding with our research,we have worked out the removal efficiency of the total nitrogen and total phosphorus in different seasons and in a two-day period of the hydraulic residence time.Our experiment results show that the removal efficiency of the total nitrogen and total phosphorus by the vertical flow wetland proves better than that of the surface flow one.The removal efficiencies of the total nitrogen by vertical flow in spring,summer and autumn,winter are 65.6%,86.0% and 47.6%,whereas via surface flow they are only 53.8%,73.4% and 34.0%.While the removal efficiencies of the total phosphorus in three phases by way of vertical flow are 62.3%,86.6% and 41.1%,they are only 47.4%,43.0% and 16.5% by surface flow.According to the seasonal difference of the total phosphorus removal efficiency,the best removing efficiencies take place in summer and autumn,then followed by spring,with the last efficiency followed in winter.In comparison with the surface flow wetland,the removal efficiency of the vertical flow constructed wetland tends to be similar for all the seasons.Its average removal efficiency in winter is only 16.5%.The analysis also shows that the artificially constructed wetland is feasible to treat the secondary effluent and proves to be more satisfactory for water quality control in the landscape lakes or canals.