HENRY’S LAW CONSTANTS OF VOLATILE ORGANIC COMPOUNDS IN ACTIVATED SLUDGE AND WASTEWATER ... 181 Henry’s law constants of volatile organic compounds in activated sludge and wastewater at 298 K

Henry’s law constant is an important equilibrium factor in volatile organic compounds (VOCs) mass transfer process. The air-water dimensionless Henry’s law constants (KH) and the dimensionless apparent Henry’s law constants (K’H) in air-activated sludge mixed liquor and air-wastewater system for volatile organic compounds (VOCs) were measured at 298K. Hydrophilic VOCs (isopropanol and acetone) and hydrophobic VOCs (toluene and pxylene) were used as target compounds. Deionized (DI) water, a pasteurized wastewater with a maximum dissolved total organic carbon (TOC) content of 700 mg/L and DI water diluted pasteurized activated sludge (mixed liquor) with a maximum suspended solid concentration of 40,000 mg/L were used as liquids. K’H of the hydrophilic compounds in the mixed liquor with the maximum suspended solid concentration were 13 to 21% higher than those in DI water. Those for toluene and p-xylene decreased up to 69 and 86%, respectively, in the mixed liquor. K’H of all the test compounds in the wastewater was only 1 to 11% smaller than those in DI water. A model was proposed for correlating K’H with wastewater TOC and activated sludge concentration using an organic carbon-water partition coefficient (KOC) and activated sludge-water partition coefficient (KP) as model parameters.