Studies On Intensive Aquaculture Ecological Engineering And Recirculating Water Flowage Principle

In recent years there has been a decrease in aquatic products from rivers and lakes due to an increasingly serious pollution. Alternately the pollution that the wastewater drained from aquaculture farms has intensified contradiction between traditional aquaculture and environment control. To develop sustainable freshwater fishery on the basis of the lowest invest and list resource is being extremely urgent. The paper is divided into two parts .The first part aims at an integrated production system, which is composed of Chinese turtle wastewater and plastic greenhouse where vegetables are irrigated with wastewater drained from turtle pond. It discussed chemical and microbial variation law of water in turtle greenhouse, nitrogen income and expenses of wastewater and the role of waterhyacinths in sewage ecological treatment system. It results that nutrition such as nitrogen, phosphorus, calcium, potassium, magnesium and mineral nutrition various little with season. Ammonia nitrogen predominates in pond water and the concentration of nitrogen is relatively low. The level of ammonia-nitrogen depends to a large extent on ammonia germ. The vegetable cultivating experiment on four soils and four substrates controlled with commercial nutrient solution indicates that soils and substrates have a high exiling rate for ammonium nitrogen and phosphorous as red soil is higher than that of others and the exiling rate is 95.3% and 96.8% respectively and the phosphorous exiling rate of pearl rock+coal cinder+sand substrate is 96.0% .The nitrate in leakage water is higher than irrigation water. As a result that various soils and substrates demonstrate different adaptability to utilizing wastewater, alluvial soils and pearl rock +coal cinder substrate prove better adaptability than others do. The pH level of red soil can be raised while the available calcium and potassium increased in soils by means of turtle pond 111 (2001) wastewater irrigation. Lettuce treated with four different irrigation solution is carried on two red soils, the exiling rate of ammonia-nitrogen is more than 90% by red soils, the survival rates of plants irrigated with turtle pond wastewater is higher than controlled group obviously. The field experiment on different plating form indicates that fruit weight, total sugar, apple acid of tomato treated with turtle pond wastewater and commercial nutrient solution has indistinctive variant. Substrate irrigated with turtle pond wastewater has a good ability to utilizing sewage. Plants root and root hair on soilless cultivating tomato absorb and filter suspension and solid residue finely. The suitable quantity match of turtles to the area of plants is 1:0.6 when the turtle pond wastewater used for soilless culture in practice. Waterhyacinths shows a tine ability to purify Chinese wastewater and exiling rate for ammonium ammonia nitrogen, nitrogen, COD and phosphorousa is 71.5%, 88.1%, 68.5% and 90.7% respectively, purify model to ammonia nitrogen is obtained through test. Another part is a design of recirculating production systems. The facility is designed to produce 130,000 kilogram of fish annually, with the first crop to be single-male tilapia and freshwater pomfret. This paper details the design of the production system being implement in this project. Octagon tanks make good culture vessels because they can provide a uniform culture environment ,can...