Dynamics of the structure and activity of microbial comunities during the composting of weathered hydrocarbons-contaminated soil.

MORELLI I.S. , DEL PANNO M.T., COPPOTELLI B.M., CORAZZA M.S., IBARROLAZA A., HARIYO D.D., LOVISO C.L., LOPEZ A.M. , MADUEÑO L. , NEGRÍN M. , PESSACQ J. , DALLO M.G., AND TORRES VILLAR C.

Messina, Italia

Simposio; 14TH International Biodeterioration & Biodegradation Symposium IBBS-14; 2008

International Biodeterioration & Biodegradation Society

The composting of soil contaminated with hydrocarbons has received increased attention as an ex-situ biorremediation technology. This work presents the results obtained in a field-scale study to assess the effects of diferent aeration and mixing conditions on the dynamics of microbial communities and hydrocarbon degradation in teh composting bioremediation process of weathered hidrocarbon-contaminated soil at a location owned by Repsol YPF in Malargue, Mendoza, Argentina. Two 200m3 biopiles consisting of hydrocarbon contaminated soil, goat manure and sawdust were prepared. Two treatments were carried out using aeration as the variable condition. The first used periodical mechanical mixing (defined as BV), whereas the second applied blower aeration via perforated pipes situated at the bottom of the biopile (defined as "BA"). The samples were taken monthly during 4 months. Three composite samples representing the surface, middle and bottom of the biopile were analysed at each time. The number of culturable heterotrophic bacteria (R2A-agar), aliphatic hydrocarbon degradin bacteria (MPN) and PAH degrading bacteria (MPN) were determined. Microbial activity dynamics was assessed by means of enzymatic activities (deshidrogenase phosphatase, urease and lipase). Physiological profiles of the microbial communities were analyzed using BIOLOG(R)ECOplate and genetic diversity using PCR-DGGE. Unambiguous differences were found in genetic and physiological diversity of the microbial communities of the two treatments. Treatment of biopile "BV" provoked a stimulatory effect on enzimatic activity of soil compared to biopile "BA". These results are consistent with the grater hydrocarbons elimination obtained with the "BV" treatment.