Effects of oxygen supply on the biodegradation rate in oil hydrocarbons contaminated soil

Abstract

Respirometry studies using the 10–chamber Micro-Oxymax respirometer (Columbus, Ohio) were conducted to determine the effect of biostimulation (by diverse ways of O2 supply) on enhancing biodegradation in soils contaminated with oil hydrocarbons. Soil was collected from a former military airport in Kluczewo, Poland. Oxygen was supplied by means of aerated water, aqueous solutions of H2O2 and KMnO4. The biodegradation was evaluated on the basis of O2 uptake and CO2 production. The O2 consumption and CO2 production rates during hydrocarbons biodegradation were estimated from the slopes of cumulative curve linear regressions. The pertinent intrinsic and enhanced biodegradation rates were calculated on the basis of mass balance equation and O2 uptake and CO2 production rates. The biodegradation rates of 5–7 times higher as compared to a control were observed when the aqueous solution of KMnO4 in concentration of 20 g L−1 was applied. Permanganate is known to readily oxidize alkene carbon – carbon double bonds; so it can be successfully applied in remediation technology for soils contaminated with oil hydrocarbons. While hydrocarbons are not completely mineralized by permanganate oxidation reactions, their structure is altered by polar functional groups providing vast improvements in aqueous solubility and availability for biodegradation. The 3% aqueous solution of H2O2 caused significant improvement of the biodegradation rates as compared to a control (on average about 260%). Aerobic biodegradation of hydrocarbons can benefit from the presence of oxygen released during H2O2 decomposition. Adding of aerated water resulted in an increase of biodegradation rates (about 114 – 229%) as compared to a control. The aerated water can both be the source of oxygen for microorganisms and determine the transport of substrate to bacteria cells.