ESTIMATING EMISSIONS OF 20 VOCS .1. SURFACE AERATION

The emission rates of semivolatile organic compounds during surface aeration can be estimated from the oxygen mass-transfer coefficient K(L)a(O2) and a modified coefficient PSI(M), which incorporates the fraction of liquid-phase mass-transfer resistance to total resistance. In order to verify this method, the mass-transfer coefficients for oxygen and 20 volatile organic compounds (VOCs) were simultaneously measured in a laboratory-scale surface-aerated reactor. Using these measurements the ratios of gas-phase and liquid-phase mass-transfer coefficients were determined by nonlinear regression. These ratios then were used to estimate the fraction of liquid-phase resistance to total resistance. The method was validated by excellent agreement between observation and theory. The correlation between the ratios of gas- and liquid-phase transfer coefficients and specific power input was also studied.