Biotransformation of coal fly ash with high carbon content; behavior and release patterns of coal fly ash constituents under the influence of allochtonic Pseudomonas stutzer MT1

Abstract

The aim of this study was to analyze the influence of Pseudomonas stutzeri MT1 on the weathering of CFA, with particular emphasis on the transformation of unburnt carbon. Batch experiment with two common types of coal fly ash (one with high carbon content) showed that microbial transformation leads to metal (loid)s and organic compounds release. The concentrations of metal (loid)s leached from CFA were the highest for As and Al, reaching 951 μg/L and 1353 μg/L respectively, in the presence of bacteria. It was shown that some metal (loid)s (Al, Fe, Cr, As) leached in higher quantities when bacteria used CFA as a sole carbon source as compared to variants where external carbon source was provided. Anthracene or phenanthrene were present in every leachate variant. The addition of bacteria resulted in a higher presence of short-chain carboxylic acids as well as 9,10-anthracenedione, which is assumed to be a product of the bacterial oxidation of anthracene. Based on the performed experiments we noticed that the microbial consumption of carbon contained within CFA was crucial to increasing the leaching rate of metal (loid)s, which may have consequences for the long-term storage of CFA.