| In recent years, China's traditional pattern of pond aquaculture create a serious pollution impact on water environment, which mainly relies on water and oxygen and other elements to ensure the intensive aquaculture production.There are breeding facilities against environmental changes in water quality and water pollution, low water quality deterioration pond, pond aging, over-medicated and other issues, nutritious substances emitted during cultivation increased the load on the fragile natural environment.Aquaculture in China, producing a large number of aquaculture effluent discharged into rivers and lakes of the main reasons for deterioration of water quality. Treatment of aquaculture wastewater has become an urgent need. This article focuses on the changing pattern of pond culture, exploring a kind of submerged plants based on ecological restoration, ecosystem with a variety of effective ways to achieve the emissions cuts breeding, improving the comprehensive utilization of water resources, achieving phase culture model and ecological restoration Combination of integrated technologies. Launched a more comprehensive system model key technology research and build the project, established a pond aquaculture ecological engineering technique to repair the water environment. improve pond water quality and water ecosystems, reducing the amount of sewage farming pollutant emissions and ecological landscape pond construction.Achieve comprehensive utilization of aquaculture water resources, and promote the healthy development of ecological agriculture, and promote a new socialist countryside construction.The first phase, Select the Yangtze River Delta common submerged plants. Submerged plants in the laboratory study of nitrogen and phosphorus removal capacity and the ability to test for organic pollutant removal. The second stage, investigate aquaculture ponds pollution in Zhi Hugang district of Taihu Lake in Wuxi City.Through the survey results, analysis of aquaculture ponds contaminated sources and main features. Master output flux in shrimp pond pollutants.The basis of experiments and investigations by the above analysis, lay the foundation of submerged plants breeding pond for pollutant reduction and control. The third stage, in accordance with the concept of ecological management, using submerged plants reduce pollutants in experimental aquaculture ponds.Construction of the ecological concept of a gradual step by step and aquaculture water aquatic food web, in order to achieve a strong self-purification capacity, the virtuous cycle of aquaculture ecosystems. At the same time the analysis of temporal and spatial variation of water quality culture based on the establishment of ecological land aquaculture pollution control, realize the effective control of pollutants in aquaculture.The main contents and results are as follows:1) Study Vallisneria, Elodea, Potamogeton and Malay Hydrilla four kinds of submerged plants in the eutrophic water, nitrogen and phosphorus removal capacity of the comparative study. The results showed that the 4 experimental water submerged plants nitrogen and phosphorus removal rates are higher. Planting density of 3 g·L-1 of the four kinds of submerged plants on the TN removal rate of the experimental group was 43% to 65%, TP removal efficiency of 68%-88%, and Hydrilla Compared to other 3 Submerged plant species showed the highest removal efficiency of TN reached 65%, TP malaianus the removal of the best 88%. Overall, the planting density of 3 g·L-1 case, the integrated Hydrilla clean the best.2)Research and analysis Hydrilla and Elodea 2-rich submerged plants operating on three of the reduction of organic pollutants in water effect. The results show that, 7g/L Hydrilla pond culture of modern agricultural park, city park, artificial lake removal of three water CODMN were 38.42%,37.76%,16.81%; 7g/L Elodea to the three water CODMN Addition rates were 39.72%,43.35%,17.47%. Elodea on the purification of organic polluted water is superior to Hydrilla. CODMn was significantly lower than the control group (P<0.01), submerged plant clean up after the classⅡ～Ⅲstate surface water quality standards. In addition, the experiment, the density of 1g/L,3g/L,5g/L,7g/L in the experimental group of submerged plants, plant health, growth speed. However,9g/L 11g/L in the experimental group, due to planting density is too large, self-shielding effect of plants occur. There are two kinds of black smelly plant phenomenon, basically stopped growing, and accompanied by stems, leaves wilt. End of the experiment, two plants in 9g/L, 11g/L of planting density, no longer found in the survival of plants. In the practical application of ecological restoration, due attention to the control of submerged plant biomass.3)Experimental area pond survey the main sources of pollution, analysis of experimental ponds contaminated area of the main features of the mechanism and the main problems facing.Regional model of experimental ponds, ponds, and ponds of different objects into the culture water of dissolved oxygen, nitrate, nitrite nitrogen, ammonia nitrogen, total nitrogen, total phosphorus, reactive phosphorus, potassium permanganate index, all other indicators of chlorophyll aMonitoring and analysis of results showed that the experimental region ponds serious water pollution, water quality indicators are worse than the national surface water class V.Experimental regional water quality indicators of nitrogen pollution, phosphorus pollution and organic pollution is more serious and major non-dissolved nitrogen pollution, the culture water pollution, solid waste nitrogen.Experimental area of organic pollutants from surface water body type IV maximum water gradually increased, and ultimately much larger than the upper limit of V water, the same trend of the pond, gradually increasing degree of organic pollution in water.Regional water quality through real-time tracking experiment, to grasp the basic conditions of pond water, a preliminary analysis of the ecological model pond purification effect, a model aquaculture pond ecosystem and health provides the basis for optimal design.4)In this study, the experimental area in 2009 to carry out aquaculture ponds under the traditional farming pattern of emissions and pollutant fluxes of investigation. The results showed that the main pollutant N, P nutrients and permanganate index (CODMn) ect, which CODMn and total nitrogen (TN) 89.2% of total output flux; aquaculture ponds feeding volume and total nitrogen and sub-Relevance of the output flux of nitrate is higher, at 0.97 and 0.94, permanganate index and low correlation,0.79; experimental emission flux in the region, the proportion of large fish pond, reaching 53.2%, Followed by crab Pool 2 (17.4%), crab pond 1 (12.9%), fish ponds (12.3%), while the Crab Tong (3.0%) and pond turtles (1.1%) lower output flux.5) 2010 using Elodea and Hydrilla submerged plant system, the experimental demonstration of crab culture in pond area of ecological restoration in situ, carried out aquaculture pollutant reduction experiment. The results show that the breeding pond submerged plant growth model well, Elodea and Hydrilla and other submersed aquatic plants cover 55% of pond area. Nitrogen and phosphorus content remained stable throughout the year, water transparency, transparency of 0.8 m in fine weather, the growth target for the crab culture provides a more stable water environment. Dissolved oxygen in water 5mg/L or more, total nitrogen content were kept at 1.01mg/L, TP 0.14mg/L, potassium permanganate index 10.18mg /L, pH value 7.0-8.4, ammonia nitrogen is 0.23-0.28mg/L, On the whole reach of conventional water quality indicators of surface water typeⅢ, in line with crab growth, the required water quality standards. Key water quality indicators of fishery water quality discharge requirements and achieve ecological aquaculture, pollution control and aquaculture water recycling.6)From mid-December 2010, taking fish ponds in the half of the breeding water 335 m3 (50%) to model crab culture ponds, the use of submerged plants for breeding wetland treatment of sewage ectopic, breeding water cuts to carry out experiments. Key indicators for the detection of permanganate index, ammonia nitrogen, total nitrogen, total phosphorus, chlorophyll a and so on. The results showed that after 20 days of fish farming wastewater wetland treatment of ectopic good results, the main water quality indicators were significantly reduced, total nitrogen by the 3.14mg/L decreased to 1.16mg/L,65% reduction in breeding the total nitrogen in sewage Content. Of total phosphorus, ammonia nitrogen, permanganate index and chlorophyll reduction rate was 75%,55%,58% and 60%. The wetland treatment of ectopic overall water quality of surface water up to the national III standard, in which ammonia to the national ClassⅡstandard of surface water, the reduction of each pollutant in excess of 50%. |
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