Aromatic compounds range from single ring compounds to six- and even sevenring compounds. The single ring compounds along with their chemical characteristics, are commonly found as contaminants from gasoline spills and leaking underground storage tanks. These compounds, benzene, toluene, the xylenes and ethyl benzene, are collectively called BTEX. The number of leaking fuel storage tanks, estimated to have exceeded 400,000 nationwide, accounts for the widespread presence of BTEX at many locations. Of these, benzene is of most concern because it is relatively soluble and mobile in groundwater and a known and potent carcinogen. A gasoline tank located underground in Bhopal, India started to leak benzene at concentration of 4 mg/L into a groundwater which flows with 120 cm³/s in a channel with a diameter of 6 cm. Granular activated carbon filtration is most commonly used technique to treat benzene pollution. To achieve treatment, as an environmental engineer, you need to find the mass flux for benzene.