Computer Modeling industrial emissions

Abstract

Air being an important part of the environment is always required to be in a satisfactory condition for the proper functioning of the entire eco system. Air quality is being affected adversely due to several reasons such as increasing number of industries without having proper emission handling systems and increasing number of vehicles. Many industrial stacks observed in Sri Lanka today are not constructed according to the proper stack design requirements. The quality of stack emissions or the dispersion of pollutants from a specific stack is seldom analyzed mainly because of the high costs involved. Even analysis is done on the dispersion from a specific stack it is difficult to get good representative results because the meteorological conditions vary frequently. In this study a stack emission dispersion model named AUSPLUME which is developed by the Victorian Environmental Protection Authority and recommended by several organizations for 'regulatory purpose was studied. This work mainly looks at the following: 1. The applicability of the model in the Environmental Impact Assessment (EIA) 11. Model emissions from the stacks at Holcim Lanka cement plant at Puttlam with the use of AUSPLUME before and after installing a new dust handling system The purpose of the EIA is to predict and identify potentially significant environmental impacts of development projects and to suggest mitigation measures to minimize the negative impacts and maximize the positive impacts. Main stages in the EIA process are, 1. Screening ( find out whether an EIA is required) 11. Scoping ( identification of main issues) lll. Collection and analysis of information IV. Public involvement v. Communicating the findings In the process of analyzing the information AUSPLUME can be used. With available information about the stack, emissions and the meteorological data of the area of concern, the model can predict the concentrations of selected constituents at ground level or elevated levels in the down wind direction. The areas of worst impact, limit of the buffer zone, effects to the high rise buildings or effects to the selected areas of important like high bio diversity, archeology, and residences can be identified using the results obtained with AUSPLUME. For the analysis of the stack emission dispersion from the Holcim Lanka cement plant at Puttlam, the meteorological data obtained at the Palavi weather monitoring station of the Meteorological Department were used. There are two similar stacks at the factory which are placed close by and therefore both of them were considered as a single point source with an equivalent diameter. The area was considered to be a flat terrain since there were no disturbances in the vicinity. The analysis results on the dispersion of particulate matter, NOz and SOz emissions from the stack were compared with ambient air quantity standards for Sri Lanka and European Guideline values which were established by considering human health hazards other than carcinogenity. Certain values were found to be above the limits and the rest below the limit. Anyway in this analysis raw emission data were used and in the real life the raw emissions are mixed with clean air before released to the atmosphere. Therefore due to the dilution the real values can be expected to be much lower. Predicted values were compared with field measurement values available and with predicted values from SCREEN3 model. The results obtained can be used for decision making purposes with a good understanding about their inaccuracy.