Anaerobic biodegradation of petroleum based waste

Abstract

Petroleum is the most common raw energy source which causes soil and groundwater pollution during the exploration, refining, transport and storage. Since the physical and chemical treatment methods have some disadvantages as high cost and secondary waste production, biological treatment methods have become important in environmental studies. Besides aerobic degradation, anaerobic biodegradation is an alternative method that has specific properties such as less biomass production and production of biogas under different electron accepting conditions. In this study, the biodegradability of petroleum-contaminated soil was observed under methanogenic and sulphatereducing conditions at different temperatures in microcosms were inoculated with an aquifer from Leuna, Germany. Biodegradation efficiency, microbial community profile and biogas production rates of microcosms were monitored under different conditions and run for approximately 200 days. Microbial community profiles were observed by using quantitative real time polymerase chain reaction (qRT-PCR), high resolution melting (HRM) and Next Generation Sequencing (NGS) based metagenomics analyses. The performance of biodegradation was determined via Total Organic Carbon (TOC) analysis which can be pre-study for total petroleum hydrocarbon (TPH) analysis. According to the results, degradation of organic matter was more efficient under sulphate-reducing conditions than methanogenic conditions. The TOC removal efficiency was as high as 70% under sulphate-reducing conditions while the TOC removal was ignorable under methanogenic conditions. Especially, microbial community profile under 16S rRNA gene expression is highly related with chemical analysis components as TOC removal, gas production and electron acceptor utilization. Molecular microbial analyses showed that aliphatic and aromatic hydrocarbon degradation occurred in the microcosms and the higher TOC removal efficiencies were related to the change in the microbial community profiles under sulphate-reducing conditions.