Anaerobic Biodegradation of Ethylic and Methylic Biodiesel and Their Impact on Benzene Degradation

Abstract

The aim of the present work was to study the anaerobic biodegradation of benzene in the presence of ethylic and methylic biodiesel. Biodiesel was produced by methanolysis and ethanolysis of virgin sunflower oil and ethanolysis of waste frying oil, and further characterized according to the European Biodiesel Standard EN 14214 for water content, fatty acid esters content, acid value, kinematic viscosity at 40°C, and oxidation stability at 110°C. Microcosms were set up in order to assess the biodegradation of the different biodiesel types and their impacts on benzene biodegradation. Methane production and benzene biodegradation were monitored for 85 days. Denaturing gradient gel electrophoresis was used to assess impacts on archaeal and bacterial community fingerprints. The results showed that the three types of biodiesel were readily biodegraded, even in the presence of benzene. In microcosms with only biodiesel, the highest biodegradation rate and extent was observed for sunflower methylic biodiesel followed by sunflower ethylic biodiesel and waste frying oil ethylic biodiesel. Similar results were observed in the presence of benzene. The presence of any biodiesel type negatively impacted benzene biodegradation with soybean ethylic biodiesel impacting rates the least. Microbial community fingerprint analyses showed that biodiesel composition selected distinct communities according to the alcohol employed in the transesterification reaction.