Status Of Constructed Wetland Wastewater Treatment In Chongqing Villages And Selection Of Cold-resistant Wetland Plants

Constructed wetlands are widely used for town and rural sewage treatment in Chongqing, because of its low cost, low energy consumption, simple operation and management, stable treatment efficiency. Up to now, among hundreds of sewage treatment facilities in operation, constructed wetlands account for more than 65%, but most of them have some common problems. This paper surveyed some constructed wetland sewage treatment stations of village in Chongqing, analyzed the existing problems and reason, and carried out several feasible suggestions. As for wetland plant during the overwintering, this experiment screened eight kinds of local plants to a low temperature water culture and investigated their cold resistance and purification potential. The results obtained from Present study are summarized as follows:(1) The survey investigated thirteen seat constructed wetland, in which normal operation accounted for 70%,attend management accounted for 62%,normal operation, attend management and reach of discharge standards accounted for 30%.(2) There are many irregularities in the design, construction and management of wetland, For example, unreasonable selection of pre-treatment process, too large hydraulic load and organic load of wetlands, unreasonable location of wetland, layered filler incomplete filling of wetlands leaking, bed collapsed, long wash cycle of fillers, etc., they are seriously affecting purification result of constructed wetland. Therefore we carried out the advice of "Design- Build- Operate" integration mode for villages sewage treatment facilities, which will help ensure the quality of construction, normal operation and management, reduce operating costs.(3) Through screening of wetland plants experiment obtained:Acorus tatarinowii can be resistant to ten temperature environment, and slow growth at five temperature environment. It has a certain CODcr removal capacity at low temperature, nitrogen and phosphorus removal effect is very low. Considering the average temperature of winter in Chongqing is about five temperature environment, it is recommended Acorus tatarinowii as an overwintering wetland plants in Chongqing.(4) Lower the temperature is, the more seriously the plant damaged by cold, the more MDA accumulated in the plant leaves, and the root’s activity is also greatly reduced. In low-temperature environment, the root activity of plants and the amount of roots most greatly impact the removal ability of pollutants, many plant’s root activity and pollutant removal rate showed a significant positive correlation.