Research On Optimization Design Of Horizontal Subsurface Flow Constructed Wetlands In Airport Economic Zone

Tianjin Airport Economic Zone, located in the northeastern of Tianjin BinhaiInternational Airport, has developed into a collection of industrial manufacture,large-scale commercial and new urban living.With economic development and thepollution loading increasing sharply, environmental issues have become increasinglyemphasized.Oherwise, constructed wetland is a simple,cheaper and effectivewastewater treatment system and is beneficial to improving the urban ecologicalenvironmental quality.Taking the original ecological basis and advantages of wetlandsinto account,this paper mainly focus on the difference between rules of thumb andSubwet model which are utilized to design pilot horizontal subsurface-flowconstructed wetland（HSSF CW）.Furthermore, the factors which have effects ontreatment efficiencies were analyzed and investigated in this study and the bestoperation was deterimined over the corresponding condition. The recommendationson optimizing and improving the HSSF CW design were provided. Some bacteriawhich have high CODcrdegradation ability were isolated from the activated sludge ofwaste treatment plant in Tianjin Airport Economic Area.Then two psychrotrophsstrains were identified and there is the potential for application in wastewatertreatment in winter. The research results show that when hydraulic retention time（HRT） of HHSF CW guided by rules of thumb was4days, the treatment efficienciesreach the accepted level. However, parameters of HHSF CW analysized with theguidance of Subwet model were different from that determined with rules of thumb.The results show that when BOD5,NH₄^-N,TN and TP removal efficiency reach thestandard, the HRT was respectively1d,7d,7d and2d. This case study of SubWetModel demonstrated the applicability of this model in the design of constructedwetland. It can provide the theoretical basis for the design of constructed wetland.43psychrotrophs strains were isolated from the activated sludge of waste treatment plantin Tianjin Airport Economic Area. The CODcrdegradation ability of singlepsychrotroph strain screened was analysed in the simulated domestic wastewater at6℃.The results showed the variation of degradation ability encountered in test. TheCODcrremoval rate ranges from20%to50%. K36was identified as Comamonastestosterone and K38was identified as Serratia fonticola. The growth rate of two psychrotrophs strains suggested that the psychrotrophs have a high activity at lowtemperature. There is the potential for application in wastewater treatment.