DEVELOPMENT OF A FULLY SUSPENDED, MULTISTAGE BIOREACTOR SYSTEM FOR TRICHLOROETHYLENE DEGRADATION BASED ON SOLUBLE MONOOXYGENASE COMETABOLISM

The design and operation of a pressurized dual-staged continuous flow bioreactor for the biodegradation of trichloroethylene (TCE) is presen ted. The reactor was designed to maximize the utility of the enzyme so luble methane monooxgenase (sMMO) by the methanotroph, Methylosinus tr ichosporium, OB3b (PP358), which can produce sMMO even in the presence of copper. Methane-fed cell growth in a continuous stirred tank react or (CSTR) was decoupled from TCE oxidation in a methane-free series of plug-flow columns, minimizing competitive inhibition. The biomass con centrations were maximized by operating the reactor at 3.04 atm, incre asing the gas-phase solubility of methane, which increased the growth rate of the cells. Furthermore, washout of the reactor biomass in the continuous flow-through system was minimized through the use of a tang ential now dewatering device. The biodegradative potential of the reac tor was demonstrated by feeding TCE at concentrations of 0.2 mg/L and 1 mg/L at 2 mL/min. The TCE was completely degraded when TCE was fed a t 0.2 mg/L and over 95% of the TCE fed at 1 mg/L was degraded. The mea sured TCE losses were due entirely to biodegradation. Batch abiotic ex periments showed the reactor held pressure, and losses due to strippin g and adsorption were minimal over 4 h. The TCE was fed abiotically in to the reactor at 1 mg/L, and 92 h of operation was necessary for the reactor TCE concentrations to accumulate to that of the feed. The abio tic mass balances demonstrated that in the absence of biodegradation, the reactor TCE concentrations would accumulate to that of the feed. T he ability to close mass balances, coupled with the ability to closely control and monitor reactor conditions, allows for a system that may be utilized to construct a mechanistic model describing the kinetics o f TCE degradation by sMMO and may potentially maxi mite the ut iii ty of the methanotrophs for TCE biodegradation at high feed concentration s.