Study On Construction Combined Artificial Wetland For Treatment Of Polluted Urban Stream Water

As an important ecological rehabilitating technique to treat sewage in pollution receiving rivers of China's urban areas,constructed wetland technology does not only improve water quality of the rivers,but beautifies the environment to form the beautiful landscape.Constructed wetland acts as a huge ecological system,where there are many kinds of plants and microorganisms.It has complex ecological structure and its ecological system is easily subject to changes of temperature and water quality,etc.Thus,it is very necessary to study on the wetland technology that is designed to purify pollution receiving rivers in urban areas and optimize the parameters of the constructed wetland technology.This paper targets at Shijiazhuang's Xiaohe surface current constructed wetland and Hebei University of Science and Technology constructed wetland sewage treatment pilot experiments devices to study practical effect and technique characteristics of three types of constructed wetlands,which treat sewage from sewage treatment plants in urban areas and meet environmental water quality standard for surface water?GB3838-2002?Class V.The microflora structure in sediments of the constructed wetlands was also investigated.See the followings for the main contents and results:1)Study on sewage treatment of Xiaohe surface current constructed wetland.By continuous monitoring water quality of upstream?inlet?,midstream and downstream?outlet?in Xiaohe wetland once every month from January to December of 2015,role of constructed wetland system in purifying CODcr,NH₃-N,TN and TP in wastewater,as well as influence of seasonal variation in purification,was analyzed.The results showed that under the existing water flow and inlet water quality,using the constructed wetland,major pollutants index of the effluent can reach the surface water quality standard Class V,System removal rate of COD,NH₃-N,TN,TP was 65%,70%,68%,70%.2)Pilot test of Hebei University of Science and Technology constructed wetland sewage treatment.Sewage treatment effects at three different residence times were compared and the treatment effects in different seasons were analyzed.The results showed that the constructed wetland sewage treatment system in which the horizontal sub-surface flow and the vertical flow were combined was superior to the system which only included either horizontal sub-surface flow or vertical flow in treating the sewage,System removal effect of NH3-N,COD,TP,in HRT?HSFCW?= 24 h,HRT_VSFCW= 16 h,are the best,the highest removal rate were 85.0%,85% and 80%,separately.3)Analysis of biodiversity in wetland sediments.16 S rRNA sequencing method wasused to analyze the sediments of Xiaohe constructed wetland and discuss biodiversity in wetland sediments in pollution receiving rivers.Results showed that the Xiaohe wetland sediment microbial advantage bacterium community composition is different from other river water,but structure is not completely the same,the flora has its own characteristics.Then,analyze and study microorganism in wetland sediments at the fast and slow water flow rate,respectively.The influence of flow rate on purification effect and structural feature of microorganism community in wetland sediment at different flow rates were further investigated.