Biodegradation of aromatic compounds in a self‐cycling fermenter (SCF)

Abstract

ABSTRACT. .The Self-Cycling Fermentation (SCF) techniql 1 e was applied to the biodegradation of several aromatic compounds by Pseudomonas putida and p"'j'eudolllomis fluorescell ..... The SCF technique was shown to be a useful research tool in aromatic biodegradation studies as weil as a potential pollution treatment method. Advantages of SCFs include stable and highly repeatable performance and almost complete substrate consumption. Biomass concentration.cycle time and the minimum dissolved oxygen level were monitored from cycle to cycle and the variation of these parameters during steady-state operation was less than 5(X,. The aromatic compounds used in this ~tudy were sodium benzoate, p-anisaldehyde and 4-methoxybenzylidine-4-n-butylaniline (MBBA). Consumptions of 93-100% were achieved for thesc compounds usingtheSCFtechnique. Consumption rates ofaromatic compounds wereshown to he considerably higher than in conventionaJ fermenters. Cycle time was found to he a usefuJ parameter forcomparing growth of ditrerent organisms on aromatic substrates. The cycle tirr.e was dependant on substrate concentration for p-anisaJdehyde. This dependence was shown to be due to the presence of an unidentified, inhibitory intermediate. .,

Application of Feedback Control Based on Dissolved Oxygen to a Fixed‐Film Sequencing Batch Reactor for Treatment of Brewery Wastewater

“…Assuming that this fraction could be removed by settling, this reactor configuration seems to be capable of 90 to 99% (an average 95%) treatment efficiency based on soluble BOD (SBOD) removal, despite variable influent loading. This confirms that the near-complete removal of soluble substrate observed in earlier SCF applications using monocultures and defined substrates (Brown and Cooper, 1992;Sarkis and Cooper, 1994;Cooper, 1990 and1991;and Zenaitis and Cooper, 1994) also occurs with a mixed microbial consortium operating on complex industrial wastewater.…”

“…Self-cycling fermentation control has been used in semicontinuous aerobic processes using a single strain of bacteria for the production of biosurfactants Cooper, 1990 and1991) and antibiotics (Zenaitis and Cooper, 1994) and the degradation of specific hydrocarbons (Brown and Cooper, 1992) and aromatic compounds (Sarkis and Cooper, 1994). From these studies, it was shown that this control technique was inherently stable and produced repeatable results.…”

Synchronized populations of Escherichia coli using simplified self-cycling fermentation

“…In earlier studies the cycle time was found to be very close to the doubling time and it was accepted that it would be equal to the minimum doubling time (maximum growth rate) of a culture growing in a batch fermenter (Brown and Cooper, 1992;Sarkis and Cooper, 1994). It is clearly not the case here.…”

“…These are compared to the methods and values for the work presented here. When available, the syn- Sarkis and Cooper (1994) Pseudomonas putida ATCC 12633 DO Load cells a --0.66 Wentworth and Cooper (1996) Candida lipolytica ATCC 20390 DO Load cells a --0.80-0.84 Marchessault and Sheppard (1997) Alcaligenes chrony index, the standard deviation of the volume exchanges and that of the cycle time were also listed.…”

“…Since there is a doubling of the cells in the reactor at the same time in each cycle, the number of cells in the harvest and at the beginning of each new cycle is constant. As well as leading to synchronous populations, this process also has the advantage of allowing the control strategy to be based on the biodegradation of problem pollutants (Brown and Cooper, 1992;Hughes and Cooper, 1996;Sarkis and Cooper, 1994) and/or the production of valuable (Brown and Cooper, 1991;Marchessault and Sheppard, 1997;McCaffrey and Cooper, 1994;van Walsum and Cooper, 1993;Wentworth and Cooper, 1996;Zenaitis and Cooper, 1994). As successful as the early work was, limitations with the monitoring and complications due to the method of cycling prevented the further development of the technique into a commercially viable process.…”