Estimation of VOC Emission from Wastewater Treatment Unit in a Petrochemical Plant Using Emission Factors

摘要

Wastewaters in petrochemical industries contain large amounts of Volatile Organic Compounds (VOC's) and emission of these compounds into atmosphere causes air pollution. VOC's are toxic and potentially carcinogenic chemicals and their emission should be controlled. In this study, Benzene, Toluene, Ethyl benzene and Xylenes (BTEX) were selected as major components of VOC in the petrochemical wastewater and emission from wastewater treatment facility were estimated by EPA's WATER9; software has been developed on basis of air pollutants Emission Factor. For validation of estimating results, the emission of BTEX from different basins was also measured experimentally by purge and trap method. The results of experiments showed that BTEX components contain as high as 80% of total VOC in selected petrochemical plant. Also, comparison between the results of WATER9 prediction and experimental data showed that WATER9 estimations have error but these errors are rather acceptable in high concentration of pollutants and these emission factors are able to estimate emission rate of some VOC's. The highest errors were for toluene in comparison with other components i.e. 25 and 52% in API and Equalization basins respectively. Finally, the emission rates of selected VOC's from different parts of the wastewater treatment unit were estimated and results showed that in overall view, basins with aeration and mixing have high emission rates.