FIELD-SCALE TESTING OF A 2-STAGE BIOREACTOR FOR REMOVAL OF CREOSOTE AND PENTACHLOROPHENOL FROM GROUND-WATER - CHEMICAL AND BIOLOGICAL ASSESSMENT

A two-stage, field-scale bioreactor system was used to determine the e fficacy of bioremediation of creosote- and pentachlorophenol (PCP)-con taminated ground water at the abandoned American Creosote Works (ACW) site in Pensacola, Florida. In separate 15-day runs of the field-scale (454L) system, bioreactor performance in the presence of specially-se lected microbial inoculants was compared to that observed using non-sp ecific biomass. In the first run, Bioreactor #1 was amended with nutri ents, surfactants and microorganisms (strains CRE 1-13) that were isol ated from soil at ACW and selectively cultured for their ability to bi odegrade monitored creosote constituents. After 4 days of organism acc limation and degradation of organic contaminants, the batch system was converted to a flow-through regime. Effluent was transferred to Biore actor #2 where Pseudomonas paucimobilis strain EPA 505 and Pseudomonas sp. strain SR 3 were introduced. A second 15-day bioreactor run was c onducted using indigenous bacteria and microorganisms from a waste wat er treatment facility that was designed to treat effluents containing PAHs and phenolics. Bioreactor performance was evaluated by chemical a nalysis of feed water initially pumped into Bioreactor #1 and clarifie d effluent from Bioreactor #2. These materials were also tested for to xic/teratogenic responses with developing embryonic Menidia beryllina, with Microtox(R) 5-min EC50 tests, and with Ceriodaphnia dubia 48-h L C50 tests. Results obtained with specialty organisms in the first run of the field-scale bioreactor showed that, on average, 70.6% of polycy clic aromatic hydrocarbons (PAHs) and heterocycles were degraded. Only 36.9% of the pentachlorophenol (PCP) present was biodegraded, apparen tly because of low cell counts and incomplete induction of Pseudomonas sp. strain SR 3. A concomitant 67- to 74-fold decrease in toxicity wa s measured in Microtox(R) 5-min EC50 and Ceriodaphnia 48-h LC50 values , respectively. No reduction in toxicity/teratogenicity was measurable in tests with embryonic M. beryllina. In the second 15-day run of the bioreactor, microorganisms from an industrial waste water treatment f acility averaged 51.0% biodegradation of PAHs and heterocycles. Degrad ation of PCP was 81.0%, a value substantially higher than in the first run. An 87-fold reduction in toxicity was measured with the Microtox( R) 5-min EC50, but only a 2.9-fold reduction in acute toxicity was mea sured in the Ceriodaphnia 48-L LC50 test. In the second bioreactor run , samples taken from Bioreactors #1 and #2 indicated reduced embryo to xicity/teratogenicity. At the 1% test concentration most embryos devel oped normally and hatched. Larvae were also normal.