The Study of Wintertime Heat Preservation Measures in Subsurface Flow Constructed Wetland in Northern China

As a new type of wastewater treatment technology, constructed wetland become more and more popular at present due to cheap cost, non-secondary pollution and other advantages. However, constructed wetland could not take regular operation because of cold weather in reducing its efficiency. In view of this, comparison tests on four main pollutants and the water temperature were conducted among three different insulation measures for two years. The test results indicate that COD, TN and NH 4+-N removal rate was 30%~45%, 40%~60% and 35%~60%, respectively, based on thin-film method of insulation measures processing system. These removel rates were approximately 10%~20% higher than the greenhouse method and frozen method. The content of TP in the water fluctuated significantly, with the removal rate ranging 19%~70% and release of P. Despite of this, the removal rate was higher than the greenhouse method and frozen method. By applying SPSS 16.0, significant difference was discovered in water quality from constructed wetland with thin-film compared with frozen method and greenhouse method. By monitoring water temperatures at the aeration tank and its outlet, it was discovered that temperature in constructed wetland with thin-film was much higher than frozen method and greenhouse method, which proved that thin-film method has ability to improve artificial wetland efficiency. Therefore, thin-film insulation measure should be promoted for its convenience and cheaper cost