Biodegradation of chlorinated aliphatics and aromatic compounds in total-recycle expanded-bed biofilm reactors

Abstract

Ground-water contamination by chlorinated aliphafic compounds is a major cause for concern because of their toxicity. This study examined the biodegradation of trichloroethylene and aromatic compounds by microbial consortia enriched from contaminated subsurface sediments. The consortia were capable of utilizing methane and propane as sources of carbon and energy. Two continuously recycled expanded-bed bioreactors were inoculated with (1) the subsurface consortium, and (2) P. fluorescence, P. putida (strains pRB1401 and pWWO), and M. trichosporium OB3b. An uninoculated reactor containing 0.2% sodium azide and 0.5% formalin served as the control. Methane (5% v/v) and propane (3% v/v) were maintained by batch feeding through the course of the experiment. Greater than 97% degradation of trichloroethylene was observed over a period of 12 d. More than 99% of benzene, toluene, and xylene were degraded within the first 7 d. Dissolved oxygen levels were measured and found to be in the range 4.9-6.5 mg/L throughout the experiments.

Integrative approaches for assessing the ecological sustainability ofin situbioremediation

“…(Donlan, 2002;Filloux & Vallet, 2003;Pasmore & Costerton, 2003;Ward et al, 2003). The role of the microbial biofilm in the improvement and enhancement of biodegradation was realized quite early by the initial studies, wherein the kinetics of biodegradation of chlorinated aliphatic compounds and polychlorinated hydrocarbons were hastened with the use of biofilm reactors (Fathepure & Vogel, 1991;Korde et al, 1993). However, the same has been confirmed only by some of the recent systematic studies (Michel et al, 2007;Schaule et al, 2007).…”

The performance and oxidation stability of sustainable metalworking fluid derived from vegetable extracts

“…Research that has been undertaken by many scientists worldwide has shown that an estimated 700 000 to one million workers are exposed to MWFs in the United States. As MWFs are complex in their composition, they may be more toxic than their components and may be an irritant or allergenic even if the raw materials are safe [6]. Both the bacteria and fungi can effectively colonize the cutting fluids and serve as a source of microbial toxins [7].…”

Biological fixed‐film systems

“…Two continuously recycledbed bioreactors, inoculated with microbial consortia enriched from contaminated subsurface sediments and with Pifluorescene. P. putida, and Methylosinus trichosporium were used to biodegrade chlorinated aliphatics and aromatic compounds (Korde et al, 1993). Greater than 97% degradation of TCE and more than 99% of benzene, toluene, and xylene were removed over periods of 12 and 7 days, respectively.…”