| Baiyangdian is the largest lake in Hebei Province and has outstanding ecological value.As the river with the largest amount of water flowing into Baiyangdian,the Fu River has long been in the Grade V or worth than Grade V in GB3838-2002,which has an impact on the water environment quality of Baiyangdian.This thesis took Fu River water as the research object and reduced the pollution of organic matter and nutrients by horizontal subsurface flow constructed wetland(HSSFCW);optimized the wetland matrix configuration to constructed the HSSFCW simulation device;investigated the efficiency of HSSFCW treatment of Fu River water and its operating characteristics,and based on the dynamic research results,a horizontal subsurface flow constructed wetland-ecological buffer pond treatment process was preliminarily designed to provide technical supported for the design of the Fu river estuary wetland project.The main findings were as follows:The maximum adsorption capacity of zeolite,vermiculite and anthracite for ammonia nitrogen were 72.3 mg/kg,610.9 mg/kg and 45.7 mg/kg,while the maximum adsorption capacity for TP was148.0 mg/kg,226.2 mg/kg and 237.7 mg/kg.The kinetic adsorption results showed that the optimal mixing volume ratio of the three substrates was 2:1:1.After adsorption at this ratio for 24 h,the adsorption capacity of ammonia nitrogen and TP in Fu river water were 11.8 mg/kg and 3.6 mg/kg,the corresponding removal rates were 27.3%and 86.7%.HSSFCW was constructed with the mixed substrate of this ratio,and biofilm was produced on the surface of the substrate using the activated sludge inoculation method.After 20 days of continuous operation,the effluent quality was stable and the device was successfully started.During operation,the optimal hydraulic retention time of HSSFCW was 24 h.Under this hydraulic retention time,when the influent COD,TP,TN and ammonia nitrogen were 34?40 mg/L,0.1?0.25 mg/L,2.6?3.1 mg/L and 1.6?2.0 mg/L,the water quality of wetland effluent can reach Grade?in GB3838-2002;When the influent COD,TP,TN and ammonia nitrogen were 43?48mg/L,0.3?0.5 mg/L,13?17 mg/L and 3?5 mg/L,the indicators of wetland effluent(except TN)reached Grade?in GB3838-2002.The temperature has a significant effect on the removal effect of water quality indicators except TP.When the water temperature was reduced from about 20?to about 10?,the removal rate of COD,TN,ammonia nitrogen and nitrate nitrogen in the wetland was reduced from more than 60%to about 30%.The wetland microbial community was richer in summer than in winter.The Ace index of summer samples can reach more than 3000,while the Ace index of winter samples was only about 2000.In the two seasons of microbial samples,compared with the substrate,the nitrifying bacteria in the root soil were higher,and the denitrifying bacteria were opposite.The spatial differences in the distribution of the two species of genus enabled nitrification and denitrification within the wetland system.Through on-site investigation and combined with the experimental results,the horizontal subsurface flow constructed wetland-ecological buffer pond combination system was preliminarily designed.The horizontal subsurface flow constructed wetland was designed in two stages,each wetland area was 41 hm~2,divided into 514 units,each unit wetland area was 0.08 hm~2,length×width×depth=40 m×20 m×1.2 m,the matrix was selected from zeolite,anthracite and vermiculite mixed in a volume ratio of 2:1:1;The design area of the ecological buffer pond was 21hm~2,which is divided into 10 units.Each unit was designed as a rectangle,with length and width of210 m and 100 m respectively.The plants in the pond were mainly submerged plants,accounting for 60%of the water area.The combined system expected the effluent quality to reached the Grade IV in GB3838-2002. |
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