Study On Air Environmental Capacity And Total Control Of Regional Atmospheric Organic Pollutants

Studying on regional air environmental capacity was a basic work involving scientific formulation of atmospheric total control target, rational utilization of the limited resources of atmospheric capacity as well as the improvement of air environment quality. Based on the optimal allocation of environmental capacity, the basic laws of emergence and development of air pollution were a significant practical guiding to implement scientific development view, industrial structure adjustment as well as layout optimization. It had realistic guiding significance to establish a resource-saving and envrioment-friendly society.Based on the fundamental datas of the agricultural comprehensive development region of Haining which consist of natural environment, meteorological characteristics, air environmental functional division and pollution source distribution, an equal-standard pollution load method was adopted to screen toluene and ethyl acetate as characteristic organic pollutants. Compared with the old recommended model and the new ones in guidellines, AERMOD model was more superior and applicable. The simulated concentrations of toluene and ethyl acetate were obtained by AERMOD model and the correlation curves of toluene and ethyl acetate were established as follows, y=0.8322x0.826, R2=0.8319; y=0.8546x0.8941, R2=0.7478 (y: observed concentration, x:simulated concentration). The simulation of two sorts of pollutants by AERMOD model had certain validity because the correlation coefficient was above 0.6 between observed and simulated concentrion. According to the spatial and temporal distribution characteristics of pollutants analyzed by AERMOD model, the 1st high hourly,daily,annual average concentrations were seriously over standard in sensitive objects. The accounting standard ratios of 1st high daily average concentrations of toluene between 5.83% and 479.95% among sensitive objects as well as ethyl acetate between 115.08% and 16401.44%. It was demonstrated that the contamination of ethyl acetate worse than toluene.The controlling sites were determined under surrounding environment of study area. The sensitive degree of concentration distribution in each control site, considering the parameter of population density, was analyed to define Star Harbor(management committee of he agricultural comprehensive development region of Haining) as critical controlling site which was most sensitive. The ideal environment capacity of toluene and ethyl acetate were performanced with A-vaule method. The ideal allowable total discharge of toluene from twelve relevant enterprises was 526.29t/a and the ethyl acetate from eleven relevant enterprises was 65.0t/a. In combination with functional area and contribution rate of industrial output in regional economy as well as current situation of cleaner production, the ideal environment capacity was allocated to each enterprise. The ideal allowable total discharge was ratificated by urban multi-source diffusion model (AERMOD model) to ensure the concentration under the standard of reference control condition (the ratio of days per year was above 97% which concentration of pollutants under the ambient air quality standardâ…¡). The actual allowable total discharge of toluene and ethyl acetate was 514.09t/a and 59.723t/a, respectively. Comparing with the status discharge and actual allowable discharge, the forcibly cut down scheme was proposed; on the other hand, the key cut down scheme was proposed considering the benefits of other enterprises. Owing to the high contribution rate of ChengXin Campany on critical controlling site, this company was identified as the key cut down company. The cut down amount of low elevation source of toluene was 157.25t/a and ethyl acetate was 870.84t/a. The key cut down scheme was more reasonable based on the feasibility analysis involved technical and economic factors.The controlling countermeasures were proposed based on the cleaner production concept embodied the whole process control and industry layout optimization as well as implementation policies of total control. Finally, according to the deficiency of data collection and model itself, the corresponding prospects were put forward.