Study On Diffusion Rule Of Odorous Gas Of Landfill Under Complex Topography

With the acceleration of the urbanization process,the total daily garbage has increased dramatically.At present,the most important handing method for domestic garbage is still the landfill method.In recent years,the garbage odors has disturbed resident frequently,causing protests and complaints from resident and causing very bad social impacts.In order to solve this problem,it is necessary to make a correct warning and forecast of the concentrationof odor pollution of the domestic waste landfill,so that the decision maker can develop targeted preventive measures.The most critical step is to systematically study the diffusion rule of the landfill odor.Based on CFD atmospheric diffusion model,this paper will deeply study the pollutant diffusion rule of landfill under complex topography.In this paper,the wind tunnel test of pollutants in the landfill of the university of Florence in Italy is simulated to verify the feasibility of the numerical simulation method.Then,based on the numerical simulation method,the pollutant diffusion rule of landfill under complex topography(surrounded by mountains on four sides and surrounded by mountains on three sides)is studied.The temperature field,wind speed field and the concentration of pollutants at the height of 15 m and distance from the center of the landfill along the direction of wind speed of 360 m,454m and 800 m was mainly studied in this paper.In addition,ammonia was used as the pollutant to study the minimum distance between the landfill and residential or recreational areas under the action of different wind direction angles under the condition of three sides surrounding mountains?The results show that the wind speed,direction and turbulence structure of the near-surface wind will be significantly changed by the special topography,in which the wind speed is the lowest at the foot of the windward and leeward of the mountain,and the wind speed is the highest at the rear(relative wind direction)of the mountaintop.The leeward of the mountain will generate a large range of backflow area,also with the low speed of wind.The direction of wind has little effect on the wind velocity on the mountain surface,but it is the key factor affecting the pollutant diffusion in the three sides of the surrounding mountain landfill.From using ammonia as pollution gases to study the effect distance of pollutants along the wind direction,the results show that when the wind direction angle varying from 0 ° to 90 °,the effect distance of pollutants varying from 890 m to more than 5200 m.the effect distance becomes the closest when the wind direction Angle is 0 °,while the effect distance becomes the furthest when the wind direction Angle is 45 °Therefore,the site selection of landfill should be combined with local special topography and special meteorological conditions.The minimum distance between landfill and residential or recreational areas should also be calculated scientifically,so as to avoid more residents being affected by odor pollution.For example,if the landfill is surrounded by mountains on three sides,It is recommended that the wind direction angle between the local prevailing wind and the landfill should be 0,so as to reduce the diffusion distance of pollutants.Human activities should also be avoided in the direction of the prevailing wind,as far as possible on both sides of the prevailing wind.This study can not only provide a reference for the numerical simulation of odor diffusion,but also provide a basis for the site selection of landfill and the layout of the buildings adjacent to the landfill.This study will also play a certain role in promoting the establishment of the odor pollution warning and prediction system of the landfill?...