Study On The Construeted Wetlands Technology Purifying Eutrophic Water From The Farm Of A Quaculture In Wujin District Of Changzhou

China is a big country of aquatic breeding.Along with people increasing demand for the aquatic products,which contain protein more than animal and plant,the aquaculture scale also is increaseing.But the problem was that large amounts excrement coming from fish, shrimp and crab and residual feed is produced in the during of aquatic breeding, which were easy to cause the eutrophication of the water, and seriously impact on water quality, aquatic breeding, water quality and the surrounding environment.There are three methods about physics, chemistry and biology in the filed of treatment of eutrophic water.Physical and chemical methods is fast to purify eutrophic water,but it is time-consuming,power-consuming and high cost and may cause secondary pollution.Biological method is economic, secure and lasting to purify eutrophic water.Construeted wetlands is a integrated wastewater treatment system,which includes physical, chemical, biological methods and engineering technologies. Construeted wetlands has the advantages of low investmentoperation cost, non-complicatedmanagement requirementswide application range,and can be used for different types of sewage treatmen.This study took aquaculture farms of Wujin District as an example in the Taihu area. We scientifically planed and designed a new model of ecological circulation treatment of eutrophic waterin the aquaculture farms.This new model combined the biological food chain with agricultural and piscatorial industry chain according to the economic theories of ecology,and integrated the technology of crop farming and aquaculture,the technology of artificial ecological system,the technology of agricultrual hydraulic engineering and so on. On the basis of channel cleanout and organize of dyke-dam,we designed and constructed three stage constructed wetland and aerobic treatment system.Three stage constructed wetland contained the first level of water purification system of175acres, the second level of water purification system of370acres and the third level of water purification system of12acres,which containe free surfane wetland(FSW) and subsurface flow wetland(SFW).In different construeted wetland system,we reasonably combined planting(the aquatic plant of efficient removal of nitrogen and phosphorus, aquatic ornamental and Edible and feed of aquatic plant) with aquaculture (fish,shrimpand crab). By pipeline laying and establishment of water pumping station,overflow dam and flow pump,we combined the breeding pond with construeted wetland effectively and let construeted wetlands circulate and purify aquaculture water quickly. We used for the biology of allelopathy to pre-vent and control excessive growth of algae in water body.After constructed wetlands be used,constructed wetland removed H2S,NH3-N,NO2-,TN,TP from0.073mg/L,0.72mg/L,0.35mg/L,3mg/L,0.32mg/L down to0.024mg/L,0.012mg/L,0.07mg/L,0.5mg/L,0.09mg/L respectively,Removal rate is67%,83%,80%,83.3%,67.8%respectively. The quality of water of aquaculture reached11,111standard of nation.Three stage constructed wetland treating aquaculture water realized aquaculture of ecology, health, high efficiency and sustainable development.the wastes of Agriculture and fishery enter into biogas generating pit to ferment.methane was used as clean fuel.Biogas slurry and Biogas residue was used as fertilizer.It realized the utilization of wastes. By the model of effective operation, water reaches the III level of water standard,and treat and reuse eutrophic water.The farm of aquaculture achieved non-pollution of aquaculture water.the farm of quaculture of wujin becomed ecotypic farming demonstration area in Jiangsu.