Henry’s Law Constant Variations of Volatile Organic Compounds in Wastewater and Activated Sludge

Abstract

ABSTRACTHenry’s law constant is an important equilibrium factor in the mass transfer process of volatile organic compounds (VOCs). A single equilibration technique (SET) was adopted to measure the air-water dimensionless (KH) and the dimensionless apparent (K'H) of Henry’s law constant in an air-wastewater system and air-activated sludge for VOCs at 298 K. Hydrophilic VOCs (methanol, isopropanol and acetone) and hydrophobic VOCs (toluene and p-xylene) were used as target compounds. Deionized (DI) water, (DI-water diluted and a pasteurized wastewater (abbreviated as wastewater) with a maximum dissolved total organic carbon (TOC) content of 700 mg/L) and DI-water diluted and pasteurized activated sludge (abbreviated as mixed liquor) with a maximum suspended solid concentration of 40,000 mg/L were used as liquids. (K'H) of the target hydrophilic compounds in the mixed liquor with a maximum-suspended solid concentration were 8.9 to 19.9% higher than those in DI water. Those for toluene and p-xylene decreased up to 70.8 and 88.3% in the mixed liquor, respectively. (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.