Pollution Of Nitrogen And Phosphorus Of Rural Organic Solid Waste And Its Control In Northern Erhai-Lake Basin

Organic solid waste production in China is largest in the world, annual production of crop stalks are724million tons and animal manure are2.7billion tons. The storage of N, P, K in those organic waste are respectively3.0×107tons,2.5×107tons and2.8×107tons. They are important renewable resource and have a huge potential for development in agriculture. It’s significant to conserve natural resources and control environmental pollution if processing and utilizing these organic solid waste with suitable technology.Erhai Lake is one of the nine plateau lakes in Yunnan Province. The northern basin is the birthplace of Erhai Lake, but also a main concentration of agriculture and aquaculture in Dali City. For a long time, Organic solid waste generated by agriculture and aquaculture has become a major source of nitrogen and phosphorus pollution into Erhai Lake. A research methodology which named Organic Solid Waste Research Modeling (ORSOWARE) on nitrogen and phosphorus pollution of rural organic waste in northern Erhai Lake basin was developed in this dissertation, based on Output Coefficient Model, combined with Life Cycle Assessment and Elements Flow Analysis, restricted in the circulation of nitrogen and phosphorus during the residents’food consumption and its pollution treatment. According to the research methodology, Organic Solid Waste Research Modeling has152entries and507parameters. All nodes of the model set balancing items, and checked by the mass balance equation. The calculation results shows that899.22tons nitrogen and33.38tons phosphorus was discharged into the watershed and atmosphere in2008in Northern Erhai Lake Basin. Food consumption process of residents intake1232.51tons of nitrogen and234.69tons of phosphorus from outside, and conveyed1434.3tons of nitrogen and93.11tons of phosphorus to the outside. The amount of deposited elements caused by population growth were2.05tons of nitrogen and0.684tons of phosphorus. Therefore, the food consumption process system has a loss of203.84tons nitrogen and a surplus of70.90tons phosphorus. The balance rate of Nitrogen and phosphorus reached80%. The simulation results were basically consistent with the actual investigation. So this model can be used to prediction rural non-point source pollution in a similar plateau lakes.The apparent recovery of organic solid waste is high, but the techniques of utilization can not solve the pollution fundamentally. According to the predicted results of ORSOWARE, eutrophication potential of organic solid waste in northern Erhai Lake Basin was847.51tons PO43-eq. Directly discharge of rural breeding waste was the key factor of eutrophication. N2O from organic solid waste was607.07tons CO2-eq. The storage process as well as the open burning of organic solid waste were the key factor of greenhouse gas emission.According to the pollution status, this dissertation presents a series of practical technology of organic solid waste control and conduct a comparative study of the pollution reduction. The results show that2101.15t/a nitrogen and124.17t/a phosphorus will be reduced of the watershed pollution when the collection rate were80%, so the reduction rate was respectively more than80%. Meanwhile, greenhouse gas emissions can be reduced by more than50%after technological improvements. Consider the environmental, economic, social benefits, this dissertation selected the best practical technology of organic solid waste control of rural non-point source with weight scoring method. The results show that household bio gas digesters and household compost pool with the optimal efficiency. Large and medium-sized projects consider edible fungi engineering, biogas and organic fertilizer plant in turn.This dissertation presents a best technology integration program of organic solid waste control for rural non-point source and implements in the form of demonstration projects. It reduced9.35tons of nitrogen and0.6tons of phosphorus to water in demonstration area after the implementation of demonstration projects, water pollutant reduction rate reached92.48%and81.08%. The reduction of greenhouse gas was26.89tons, gas emission reduction rate reached70.8%. All the techniques presented in this dissertation were efficiently reducing emissions of pollutants. The program even formed a set of resource technical and specification system of rural solid waste which was easy to spread, economical and practical. They effectively reduced the rural non-point source pollution load in Erhai Lake basin, and guarantees the long-term effective running of all demonstration projects. It achieved the overall objectives that pollution reduction and environmental improvement in demonstration area ultimately.