Enhanced anaerobic biodegradation of BTEX-ethanol mixtures in aquifer columns amended with sulfate, chelated ferric iron or nitrate

• Published in: Biodegradation (Dordrecht) Vol. 16; no. 2; pp. 105 - 114
• Main Authors: Da Silva, M.L.B, Ruiz-Aguilar, G.M.L, Alvarez, P.J.J
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Dordrecht Springer 01.03.2005; Springer Nature B.V
• Subjects: Aerobiosis; Anaerobic biodegradation; Anaerobic conditions; Aquifers; Bacteria, Anaerobic - metabolism; Benzene; Benzene Derivatives - metabolism; Biochemical oxygen demand; Biodegradation; Biodegradation of pollutants; Biodegradation, Environmental; Biological and medical sciences; bioremediation; Biotechnology; Biotransformation; BTEX (benzene, toluene, ethylbenzene, xylene); Dissolved oxygen; EDTA (chelating agent); Environment and pollution; Environmental Pollutants - metabolism; Ethanol; Ethanol - metabolism; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; Iron; Methane - metabolism; Methanogenesis; Mineralization; Nitrates; Oxygen; Oxygen - metabolism; Sulfates; Toluene; water pollution; water treatment; Xylenes - metabolism; Biodegradation; Ethanol; Natural attenuation; Anaerobe; anaerobic biostimulation; Iron; Nitrates; BTEX; Bioremediation; Sulfates
• ISSN: 0923-9820; 1572-9729
• DOI: 10.1007/s10532-004-4897-5

Flow-through aquifer columns were used to investigate the feasibility of adding sulfate, EDTA-Fe(III) or nitrate to enhance the biodegradation of BTEX and ethanol mixtures. The rapid biodegradation of ethanol near the inlet depleted the influent dissolved oxygen (8 mg l(-1)), stimulated methanogenesis, and decreased BTEX biodegradation efficiencies from > 99% in the absence of ethanol to an average of 32% for benzene, 49% for toluene, 77% for ethylbenzene, and about 30% for xylenes. The addition of sulfate, EDTA-Fe(III) or nitrate suppressed methanogenesis and significantly increased BTEX biodegradation efficiencies. Nevertheless, occasional clogging was experienced by the column augmented with EDTA-Fe(III) due to iron precipitation. Enhanced benzene biodegradation (> 70% in all biostimulated columns) is noteworthy because benzene is often recalcitrant under anaerobic conditions. Influent dissolved oxygen apparently played a critical role because no significant benzene biotransformation was observed after oxygen was purged out of the influent media. The addition of anaerobic electron acceptors could enhance BTEX biodegradation not only by facilitating their anaerobic biodegradation but also by accelerating the mineralization of ethanol or other substrates that are labile under anaerobic conditions. This would alleviate the biochemical oxygen demand (BOD) and increase the likelihood that entraining oxygen would be used for the biotransformation of residual BTEX.