Kinetics of BTEX degradation in a packed-bed anaerobic reactor

Abstract

The ever-increasing diversity of industrial activity is responsible for the discharge of compounds that are toxic or difficult to degrade into the environment. Some of the compounds found in surface and ground waters, usually deriving from the contamination of oil-based products, are benzene, toluene, ethylbenzene and xylenes (BTEX). To remove these compounds from contaminated water, a bench-scale horizontal-flow anaerobic immobilized biomass reactor, containing anaerobic biomass from various sources immobilized in polyurethane foam matrices, was employed to treat a synthetic substrate composed of protein, carbohydrates and BTEX solution in ethanol, as well as a BTEX solution in ethanol as the sole carbon source. The reactor removed up to 15.0 mg/l of each BTEX compound over a hydraulic detention time of 11.4 h. A first-order kinetic model fitted the experimental data well, showing correlation coefficients higher than 0.994. The apparent first-order coefficient values, k1(app), ranged from 8.4+/-1.5 day(-1) for benzene to 10.7+/-1.4 day(-1) for o-xylene in the presence of ethanol, protein and carbohydrates, and from 10.0+/-2.0 day(-1) for benzene to 13.0+/-1.7 day(-1) for o-xylene in the presence of ethanol. The BTEX degradation rates estimated here were 10- to 94-fold higher than those found in reports on microcosm studies.

Lead or cadmium co-contamination alters benzene and toluene degrading bacterial communities

“…The degradation rates and lag times in our experiments did not significantly decrease due to Cd or Pb co-contamination. Toluene had a higher degradation rate than benzene, which has often been observed in other studies (Carvajal et al 2018 ; Chang et al 1993 ; Collins and Daugulis 1999 ; de Nardi et al 2007 ). Toluene is readily biodegradable under aerobic conditions if it is the sole carbon and energy source (Carvajal et al 2018 ).…”

Plant-Wide Models for Optimizing the Operation and Maintenance of BTEX-Contaminated Wastewater Treatment and Reuse

“…Regarding gas transfer through bubbles, the volumetric liquid-side mass transfer coefficients k L a i,bub,st,cw -in clean water for a standard 20 • C temperature-and k L a i,bubin wastewater at the field temperature-are calculated by Equations ( 20) and (21).…”

“…The addition of another pollutant always resulted in competition and inhibition, with xylene being the most inhibitory [19], whilst the external carbon source could cause enrichment on BTEX degradation by bacterial cultures [20]. Anaerobic conditions could be developed in packed bed reactors or deeper layers of the biofilm, which could also show significant biodegradation [21]. Lee et al (1998) made significant steps towards modelling a highly hydrophobic compound in wastewater, and the authors explained that the biodegradation of a compound that has been adsorbed to activated sludge directly enhances its biodegradation and diminishes its discharge with the waste activated sludge.…”

Multivariate optimization of headspace-GC for the determination of monoaromatic compounds (benzene, toluene, ethylbenzene, and xylenes) in waters and wastewaters

“…Therefore, they can contaminate extensively the air, soils and surface, or underground waters [7][8][9][10]. The main sources of BTEX contamination are atmospheric deposition, leaks from underground fuel storage tanks or pipelines, inadequate effluent disposal, accidental spills of petroleum products during transport, and leaching from landfill [11][12][13][14][15][16].…”