Tempo-spatial variability in volatile emissions from a sewage-treatment plant in Surat, India

Abstract

The purpose of this research work was to evaluate the Benzene, toluene, ethylbenzene and xylene (BTEX) emissions from a Bamroli sewage-treatment plant (STP) in Surat City, India. Tiger handheld gas detector was utilised to measure emissions of BTEX during three periods of monitoring, and sewage samples were collected to determine the characteristics of sewage. The spatial variation of BTEX was determined at various treatment units of the STP during the months of November and April and represented as interpolation maps using ArcGIS. Box charts were plotted to represent the temporal variation of BTEX, which categorise the resultant data on the basis of their frequency. It has been noticed from the interpolation maps that the concentration of BTEX decreases as sewage travels from the inlet to subsequent units. Approximately 50% of all readings obtained of BTEX concentration fall within 0.5 parts per million, which exceeds the limits stipulated by the National Ambient Air Quality Standards, 5 mg/m3 for benzene. It can be concluded that more vent pipes have to be provided for the dispersion of these compounds in transmission lines. Also, some safety aids such as face masks have to be utilised by labourers who are continuously subjected to these compounds.