Biodegradation of p-nitrophenol in an aqueous waste stream by immobilized bacteria

• Published in: Applied and Environmental Microbiology Vol. 56; no. 10; pp. 2967 - 2973
• Main Authors: Heitkamp, M.A. (Monsanto Company, St. Louis, MO), Camel, V, Reuter, T.J, Adams, W.J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.1990
• Subjects: Adsorption; BIODEGRADACION; BIODEGRADATION; Biodegradation of pollutants; Biodegradation, Environmental; Biological and medical sciences; bioreactors; Biotechnology; COMPOSE PHENOLIQUE; COMPUESTOS FENOLICOS; DECHET; DESECHOS; Environment and pollution; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; MINERALISATION; MINERALIZACION; Nitrophenols - metabolism; p-nitrophenol; PESTICIDE; PLAGUICIDAS; PSEUDOMONAS; Pseudomonas - isolation & purification; Pseudomonas - metabolism; Sewage; Soil Microbiology; wastewater treatment; Water Microbiology; Pseudomonadales; Biodegradation; Activated sludge; Phenols; Bacteria; Pseudomonadaceae; Isolation; Wastes; Pseudomonas; Entrapped microorganism
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.56.10.2967-2973.1990

Microbiological analyses of activated sludge reactors after repeated exposure to 100 mg of p-nitrophenol (PNP) per litter resulted in the isolation of three Pseudomonas species able to utilize (PNP) as a sole source of carbon and energy. Cell suspensions of the three Pseudomonas sp., designated PNP1, PNP2, and PNP3. mineralized 70, 60, and 45% of a 70-mg/liter dose of PNP in 24, 48, and 96 h, respectively. Mass-balance analyses of PNP residues for all three cultures showed that undegraded PNP was 1% ( 50 micrograms); volatile metabolites, 1% cell residues, 8.4 to 14.9%; and water-soluble metabolites, 1.2 to 6.7%. A mixed culture of all three PNP-degrading Pseudomonas sp. was immobilized by adsorption onto diatomaceous earth biocarrier in a 1.75-liter Plexiglas column. The column was aerated and exposed to a synthetic waste stream containing 629 to 2,513 mg of PNP per liter at flow, rates of 2 to 15 ml/min. Chemical loading studies showed that the threshold concentration for acute toxicity of PNP to the immobilized bacteria was 2,100 to 2,500 mg/liter. Further studies at PNP concentrations of 1,200 to 1,800 mg/liter showed that 99 and 91 to 99% removal of PNP was achieved by immobilized bacteria at flow rates of 10 and 12 ml/min, respectively. These values represent hydraulic retention times of 48 to 58 min and PNP removal rates of 0.99 to 1.1 mg/h per g of biocarrier at 25 degrees C under optimal conditions. This study shows the successful use of immobilized bacteria technology to remove high concentrations of PNP from aqueous waste streams