| The activated sludge wastewater treatment system consists of a mixed community of aquatic microorganisms that transform organic and inorganic pollutants into environmentally acceptable end products. The objective of this research was to determine the potential of municipal activated sludge to biodegrade the model compound, sodium benzoate, and the recalcitrant compound, 2-chlorobenzoate, with and without microbial enhancement. Microbial enhancement included the addition to fresh municipal activated sludge of either municipal activated sludge adapted to these compounds or similarly adapted cultures of a wild type or a genetically engineered strain of Pseudomonas aeruginosa. The latter was the product of the use of Vitreoscilla hemoglobin technology.; Municipal activated sludge obtained directly from the water reclamation plant did have the ability to degrade both benzoate and 2-chlorobenzoate, and this could be enhanced by adapting the activated sludge to either compound. A 10% (v/v) addition of adapted activated sludge increased the benzoate degrading ability of fresh municipal activated sludge 3-fold. Adapting this municipal activated sludge to benzoate for more than 6 months increased its ability to degrade a 10 mg/L solution of benzoate 115-fold. Time to reach maximum enhancement (about 45-fold) for benzoate degradation was about five weeks. For 2-chlorobenzoate, projected time to maximum enhancement (20-fold) was about 25 weeks. The results suggest that significant enhancement for degradation of these aromatic compounds in wastewater could be achieved using such enricher technology.; Augmentation of benzoate and 2-chlorobenzoate degradation by addition of Pseudomonas aeruginosa, both wild type and engineered to contain the Vitreoscilla hemoglobin gene, was investigated. When grown on solid media for five weeks, PaWT and PaJC grew visibly only on benzoate, and not 2-chlorobenzoate, when each compound was provided as the sole carbon source. Both strains grew well on solid nutrient media containing 1 g/L 2-chlorobenzoate which indicated that these compounds were not toxic to either strain. |
