Emission modeling of air pollutants resulted from Baharan industrial Town, Hamadan

Abstract

Introduction: Investigation and modeling of air pollution emission resulted from construction and commissioning of small and medium industrial enterprises, like many other projects, can be considered as an appropriate method for determination of projects location and can be helpful to manage the region air quality. The great gap in modeling the emission of air pollutants before constructing the industrial Towns is the lack of sufficient information about the fuel consumption rate per hectare of various industrial groups. Regarding the importance of the evaluation of air pollutants rate before the construction of industrial Towns, the present study is indeed the first attempt seeking to provide a comprehensive and applicable method for estimating the common air pollutants' (CO, NO2, TSP, PM10, SO2) emission rate and dispersion in the industrial Towns’ construction sites (Baharan Industrial town - Hamedan and Phase II (development phase)) by obtaining the fuel consumption rate per hectare of the industrial zone. Results of the present work on the estimation of fuel consumption rate in different industrial groups can be also used for other industrial Towns. Materials and Methods:In order to investigate the fuel consumption rate per hectare of different industrial groups, some questionnaires were developed and, then, completed in 5 under-exploitation industrial groups. These questionnaires investigated the industrial units' information on the type of industrial group, surface area of the industrial unit's manufacturing department, as well as the primary and secondary fuel type and consumption rate. The results derived from these questionnaires were then processed in EXCEL software. The average fuel consumption rate for each industrial unit was different from that of other units; however, in this study, the average fuel consumption rate of different industrial units in each industrial group was used in the relevant calculations. The industrial Towns, in which the questionnaires were completed, and the number of questionnaires completed in each industrial Town were as follows: Rajaei Industrial Town (88 completed questionnaires), and Salimi (106 completed questionnaires), Foreign Investment (72 completed questionnaires) in East Azerbaijan province, Eivanaki Industrial Town (76 completedII questionnaires) in Semnan Province, and phase-I of Baharan Industrial Town (52 completed questionnaires) in Hamadan Province. The air pollutants’ emission rate must be estimated via direct test on exhaust gas at the smoke column output or by transferring the output air sample from stack. However, in this research, due to evaluation of the air pollutants rate before constructing phase-II of Baharan Industrial Town and, consequently, the relevant industrial units, the method proposed by EPA, namely AP-42, was used. The AERMOD method models the stacks at stable status and can be also used to determine the concentration of various pollutants in rural and urban regions, flat and rough regions, surface emission, and at heights from point-volumetric resources. Therefore, it is proposed for simulating the pollutants dispersion in up to 50 km areas. Finally, using ArcGIS software, results of various pollutants’ emission modeling were provided by AERMOD as the pollutants’ emission zoning maps. Results: Results of the questionnaires completed in the studied industrial Towns,in order to estimate the average consumption of various fuels (gas and gasoline) per square meter of different industrial groups, shows the average natural gas consumption rate had the highest and lowest values in the food and non-metallic minerals zones with the consumption rate of 0.023532 (m3/ha.s) and 0.00097 (m3/ha.s), respectively. Furthermore, the food 0.0135 (m3/ha.s) and non-metallic minerals 0.000263 (m3/ha.s)zones had the highest and lowest gasoline consumption rates, respectively. Results of executing the AERMOD model were obtained as the aligned curves of the pollutants' concentration in the receiver network. In the present study, the CO concentration was examined in an average 8-h annual period. According to the findings of AERMOD, the maximum CO concentration was equal to 84 µg/m3 at the geographical coordinates of 3862374.81 and 262792.31, which was less than the standard value (10000 µg/m3) determined for clean air. In the average 24-h annual period, the maximum concentration of SO2, PM10, and TSP at the geographical coordinates of (262792.31 and 3862374.81) was predicted to be equal to 29.3, 1.52, and 2.08 µg/m3, respectively. Furthermore, for CO2 pollutant in the average monthly period and at the geographical coordinates of (262792.31 and 3862374.81), the maximum concentration of 3646 µg/m3 was predicted; however, for NOX at the same geographical coordinates, the maximumIII concentration was predicted to equal 7.05 µg/m3. In the present study, investigation of the maximum concentration of the pollutants at 1-h, 8-h 24- h, monthly, and annual periods during a 1-year course indicated that concentration of the studied pollutants remained below the pre-specified standard level during the 1-year period. Conclusion: Due to the high consumption of natural gas in the Baharan industrial town, nitrogen dioxide will be the main pollutant that will be emitted from this industrial town. The results of air pollutants emission modeling resulted from Bahan Industrial Town showed that the impact of construction and commissioning of this Industrial Town on the region ambient air quality will be negligable.