Research On Scenic Water Treatment With Wavy Subsurface Flow Constructed Wetland

With the development of society and the improvement of people’s livingstandards, the scenic water plays a more and more important role in people’s daily life.However, because of the weak awareness of environmental protection and theinjection of exogenous pollutants, scenic water pollution becomes more and moreserious, which has aroused extensive attention gratually. In this case, the applicationof constracted wetland treatment system to repair scenic water quality has become ahot topic of domestic research.In this paper, a wavy subsurface flow constracted wetland （W-SFCW） wasconstructed as a small pilot plant. With several regular partition plates added inside ofW-SFCW, the waste water presented a wave-type flow state, as a result, the treatmenteffect was effectively improved. The influence of hydraulic retention time, COD ofthe influent water and the temperature to the treatment efficiency has been studied. Inorder to research the dynamic characteristics of W-SFCW’s treatment efficiency, theefficiency of W-SFCW treating scenic water was mornitoring continuously. Themovement and changes of pollutants in W-SFCW has been studied to analyze themechanism of the pollutants’ removement.The results show that, when the HRT is3d and influent flow is24.7L/d, theoptimal nitrogen and phosphorus removal efficiency is achievable. The removalefficiencies of TN, NH₃-N and TP are58.06%,63.95%and86.97%respectively.COD of influent has a major impact on the removal efficiency of nitogen. Theremoval efficiency of TN increases at first and then decreases with the increase of theinfluent’s COD, and the removal efficiency of NH₃-N decreases with the increase ofthe influent’s COD. Temperature has a major impact on the removal efficiency ofCOD, TN, NH₃-N, while has a less impact on the removal efficiency of TP.During three months’ dynamic experiments, W-SFCW operated continuously andstably. The removal efficiency of W-SFCW is very significant and the averageremoval efficiency of COD, TN, NH₃-N and TP reach72.31%,57.31%,60.05%and68.02%respectively. The average effluent concentrations of TN NH₃-N and TP satisfythe Class IV of surface water environmental quality regulation （GB3838-2002）.Finally, the mechanism of the pollutants’ removement of the W-SFCW was studied. The experiment results show that the removal of COD is very different in thehorizontal direction. The organic matter is removed mostly in the first part of theW-SFCW, in which the removal efficiency of COD receahes49.41%. TN is mostlyremoved in the lower part of the W-SFCW, while most NH₃-N is removed in thesurface of the W-SFCW. TP is removed by the adsorption of the filter instead of theplants and microorganisms.