Heterotrophic Activity of Microorganisms in Soils Treated with Quaternary Ammonium Compounds

Abstract

In situ soil modification using quaternary ammonium compounds (QACs) enhances the immobilization of organic contaminants. The feasibility of coupling contaminant immobilization with subsequent bioremediation was assessed in biodegradability tests of 14 C-labeled organic compounds in QAC-treated soils. Aqueous hexadecyltrimethylammonium (HDTMA) bromide added to soils caused increased lag periods and decreased rates and extents of mineralization of test compounds as a result of selective toxicity toward Gram-negative soil microorganisms. Toxic effects were more pronounced at higher HDTMA treatment levels and with more complex test substrates. Once bound to soil or clay, HDTMA toxicity was greatly reduced