Bioremediation of petroleum‐impacted soils from investigation‐derived wastes

Abstract

AbstractOptimal conditions for bioremediation of investigation‐derived wastes from petroleum‐impacted soils (PIS) were determined through biotreatability experiments. The PIS was collected as extruded cores obtained during sample drilling. These samples were processed into workable media prior to treatment in bioreactors. Soil moisture content in the bioreactors was adjusted to 30 percent, 40 percent, 50 percent (control), and 60 percent, dry‐weight basis, and nutrient levels were adjusted by applying fertilizer, yielding carbon (C) to nitrogen (N) ratios of 20:1, 10:1, and 5:1, versus a control C:N ratio of 140:1. Temperature, pH, viable bacterial plate counts, contaminant degradation rate, and microbial respiration were monitored. Concentrations of three selected branched alkanes in the aviation fuel contaminant, measured by gas chromatography, decreased for most treatments. The greatest degradation occurred with a moisture content of 40 percent and C:N ratio of 5:1. Increased contaminant degradation was consistent with increased microbial activity measured by respiration. There was poorer correlation between contaminant degradation and viable plate counts, which suggests that respirometry is a better measure of activity of the microbial population responsible for contaminant degradation. General plate counts, which enumerate only a fraction of the total population, may not be a reliable quantitative indicator of the actual microorganism population that is responsible for degradation. © 2003 Wiley Periodicals, Inc.