Study On Treatment Efficiency And Application Of The Constructed Wetland Treating Rural Landscape Water In A Country Of Guangdong

Constructed wetland is simulated natural ecosystem, with high purification efficiency, high removal of N,P and other pollutants, simple process equipment, easy maintenance, low energy consumption, strong adaptability to load change, low infrastructure construction costs and operating costs. The outflow of constructed wetland is biologically safe. Constructed wetland has significant environmental benefits and the value of certain characteristics of the landscape. It makes waste water recycling realized. At the stage of building a new socialist countryside, under the premise of improving farmer's living environment, combined with the actual situation in rural area, especially for rural landscape water treatment, we should strengthen research in this area.Results of the research on the treatment effect of the village landscape water by subsurface-flow constructed wetland show that:The results of efficiency experiment showed that the average removal efficiency of TN, NH4+ -N, TP, COD, SS were 56%~67%, 56%~70%, 63%~75%, 49%~58%, 79%~88%.Early of trial run, the effluent TN, NH4+-N, TP, COD slightly higher than the surface water environmental quality standard V class; trial run later, the effluent quality can reach the surface water environmental quality standard V class. Effluent TP and COD can reach surface water environmental quality standard IV class, and the effluent NH4+-N can reach surface water quality standard Class III.In this set, for TN, NH4+-N, COD, subsurface flow constructed wetland with substrate depth of 1.0m, planting cattail, density of 9/m2, hydraulic loading 0.2 m3·d-1~0.4m3·d-1, have the best removal efficiency; for TP and SS, subsurface flow constructed wetland with substrate depth of 1.5m, planting cattail & canna, planting density of 9/m2, hydraulic loading 0.2m3·d-1~0.6m3·d-1 have the best removal efficiency.Studied six sets of biological characteristics of constructed wetland system by PCR-DGGE (Polymerse Chain Reaction-Denaturing Gradient Gel Electrophoresis), the results show that: the substrate depth, plant configuration and plant cultivation density of the subsurface flow constructed wetland system does not have a significant effect on microbial community structure and distribution; Canna wetlands have relatively higer microbial abundance than cattail wetlands.Construction of constructed wetlands should follow the principles of ecological engineering and design principles first, then considering the location, shape design, plant elements configurate; In rural areas, we can also design constructed wetlands as courtyard style, street style and the centralized style base on the dispersion of the villagers.The economic accounting of experimental wetland system was like that, when daily flow is 24m3, the area of subsurface flow constructed wetlands is 60m2, the construction investment is 25,776.84 yuan, running cost is 0.09 yuan/t.The operation results of Wetlands Demonstration Project show that constructed wetland referring to previous test results runs well, the effluent quality can meet the target.Constructed wetland systems have very good effect on treating landscape sewage water, it is an effective and suitable technology for rural water environmental improvement.