Biological Activated Carbon Treatment for Removing BTEX from Groundwater

Abstract

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are common groundwater pollutants. Biological activated carbon (BAC) treatment is attractive because BTEX species are well-adsorbed on activated carbon and also easily biodegraded in the adsorber. The inoculated activated carbon columns quickly became BAC systems; they removed most of the BTEX species present in the feed. Biodegradation was primarily responsible for the overall removal of the BAC systems, and the amounts of benzene, toluene, and o-xylene removed during the 2-week treatment period were all more than their respective isotherm capacities; 1,486, 1,463, 1,537, and 1,719 mg of benzene, toluene, ethylbenzene, and o-xylene were removed in the 2.5-g BAC systems versus the available adsorptive capacities of 174, 731, 1,515, and 895 mg, respectively. The stable BAC systems were resistant to the shock loadings of higher flow and concentration and consumed less than the expected amount of dissolved oxygen. Bioregeneration enabled the long-term treatment capability of the BAC systems for removing BTEX and other pollutants without periodic carbon replacement. The coal-based activated carbon (SC) was more desirable than the coconut-based activated carbon (YK) because of its lower cost and higher degree of bioregeneration.