Efficiency assessment of air stripping packed towers for removal of VOCs (volatile organic compounds) from industrial and drinking waters

摘要

Packed column strippers are being used for removing VOCs (volatile organic compounds) contaminants from drinking and industrial waste waters. In order to evaluate the capability of packed towers for reducing the contaminant concentration to its permissible limits, a mathematical mass transfer model is developed. The model, which is based on resistances-in-series approach and considers liquid-vapor equilibria in terms of temperature-dependent Henry's constants, is successfully validated against several experimental data. The effects of key parameters, such as column pressure, temperature, gas-to-liquid flow rate and VOC inlet concentration, on the removal of different VOCs from waste waters and also on the required tower height are thoroughly considered. It is found that these parameters can have different impacts on the removal of different VOCs, and the required tower height is highly dependent on the VOC solubility and volatility. The optimum design and operating conditions of a packed tower are also determined for the maximum VOC removal and the minimum packing height.