Abstract:

In recent years, application of the Monitoring Natural Attenuation (MNA) method in petroleum hydrocarbon removal from
groundwater was widely studied. Alternatively, mass flux calculation becomes an important way to evaluate the remediation effect of MNA on removing gasoline pollutants in groundwater. In this study, ethanol and BTEX from gasoline, associated with bromide as a non-active tracer, were injected into a sand tank and their degradation was monitored. Based on mass flux method, mass reduction rates and first-order natural attenuation rate constants of BTEX and ethanol were obtained. The results showed that the mechanism of nature attenuation is important for removing fuel components in groundwater, and mass flux is an effective method to evaluate the nature attenuation, with the removal rates of BTEX and ethanol in natural attenuation to be 78.88% and 98.71%, respectively. About 98% of BTEX was removed by adsorption and intrinsic biodegradation as well as approximate 100% ethanol removed by intrinsic biodegradation. The first-order natural attenuation rates of BTEX ranged from 0.077 d-1 to 0.167 d-1. Compared with BTEX, ethanol had a larger rate (0.353 d-1), indicating that ethanol was more rapidly to be attenuated than BTEX under natural condition.

Key words: mass flux, ethanol, BTEX, natural attenuation, groundwater