Air-water partitioning equilibrium of tetrahydrofuran in an activated sludge system

Abstract

This study evaluate the effect of liquid tetrahydrofuran (THF) concentration and biomass content on the THF air-water partitioning equilibrium for a simulated activated sludge system. The equilibrium of the partition at the air-water interface is given by a partitioning coefficient (p _c) = C _g*/C _L, where C _g* denotes the gaseous concentration in equilibrium with the aqueous THF concentration (C _L). Variations of p _c with C _L in static pure water are evaluated, and high solubility of THF in water caused p _c values to drop as the C _L increased from 29.81 ± 0.16 to 297.75 ± 2.28 mg/L at a constant temperature of 27°C. Meanwhile, the hydrophilicity of THF in water induced abiomass effect, causing p _c to increase in the activated sludge liquor. Due to the co-effect of liquid THF concentration and biomass content, the p _c values of THF for the liquor of mixed liquid suspended solid (MLSS) concentration = 1220 ± 86 mg/L and THF C _L = 242.91 ± 69.09 mg/L increased 22.5% compared to those in the pure agitated water. The biomass effect on p _c of hydrophilic VOC increases the gaseous VOC emission rate from the activated sludge facilities.

Keywords:

• Partition
• Henry's law
• activated sludge
• solid phase microextraction
• single equilibration technique
• tetrahydrofuran.