Experimental Study Of Reducing Nitrogen And Phosphorus In Lakes And Reservoirs By An Aeration Sysyem

The degradation of nitrogen and phosphorus nutrients in natural water reflects mainly on the use and transformation of microorganisms and the aquatic flora for nutrients,and these degradation always consume dissolved oxygen.When natural water nutrient loads beyond its self-purification capacity,water will be hypoxic,this can cause the deterioration of the aquatic environment At thus state,nitrogen,phosphorus,iron,manganese of sediments will dissolve and release,which aggravating water eutrophication.In this paper,nitrogen and phosphorus pollution problem in lakes and reservoirs is discussed,proposing a soker house porous hose aeration system,designed to improve the water dissolved oxygen using air bubble curtain,enhance self-purification capacity of water bodies,inhibit the release of sediment contaminants,and a preliminary design of the aeration system for Tangpu Reservoir in Shaoxing City is done.The main co nclusio ns of this study are:1.Do beaker experiment of sediment pollutants release using the sediment samples from Tangpu reservoir,explore the impact of sediment overlying water dissolved oxygen state on the stable state of sediment contaminants release,such as total phosphorus,total nitrogen,ammonia,iron,manganese.Come to the conclusion that the aerobic conditions of overlying water will obviously inhibit the release of total phosphorus,ammonia,iron,manganese,the inhibiting ratio as follows:50%?70%of total phosphorus,35%?45%of ammonia,35?45%of Fe,30%?40%of Mn.So enhance dissolved oxygen of the reservoir bottom water can inhibit the re lease of sediment contaminants.2.Observe the degradation of nitrogen and phosphorus by selected aquatic plant and landscape water,study the effects of aeration and dissolved oxygen levels on the degradation of nitrogen and phosphorus.Verified that the aeration can effectively improve dissolved oxygen,thereby co ntributing to the degradation of nitrogen and phosphorus in natural water bodies.The dissolved oxygen level of aquatic plant to maintain good capability on the degradation of nitrogen and phosphorus should not be less than 5mg/L,and thus the oxygen demand of Tangpu Reservoir is 4t.3.Research the pressure and flow relationships of continuous non-uniform discharge vent pipe.Experiment the aeration of the porous hose soker house,come to the relationship of A P(the pressure difference of inlet and outlet)and Q(ventilation):Q=1.58a P+1.59(R2>0.99).And according to the evaluation criteria in this paper,the desired gas pressure is obtained as(4.5+Depth/10)bar for good aeration effect,at this time the ventilation is 8.7 m3/h.And calculated pipeline gas pressure of the Tangpu reservoir aeration system,needed to 8.3bar,the voluntary ventilation of 7 lines is about 9 thousand m3/h.4.A system of porous hose aeration for Tangpu reservoir was designed after getting the parameters of this study,it will meet the oxygen demand of Tangpu reservoir if the aeration system works 2 hours everyday by using compressed air as the gas medium.The aeration system cost was computed after the design and calculation of the main pipelines and components,obtained that construction costs 2.2 million yuan and running costs 520,000 yuan a year.