4-Chlorophenol degradation by a bacterial consortium: development of a granular activated carbon biofilm reactor |
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Authors: | M Caldeira S C Heald M F Carvalho I Vasconcelos A T Bull P M L Castro |
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Institution: | (1) Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, P-4200 Porto, Portugal e-mail: plc@esb.ucp.pt Tel.: +351-2-5580042 Fax: +351-2-5090351, PT;(2) Research School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK, GB |
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Abstract: | A bacterial consortium that can degrade chloro- and nitrophenols has been isolated from the rhizosphere of Phragmitis communis. Degradation of 4-chlorophenol (4-CP) by a consortium attached to granular activated carbon (GAC) in a biofilm reactor was
evaluated during both open and closed modes of operation. During the operation of the biofilm reactor, 4-CP was not detected
in the column effluent, being either adsorbed to the GAC or biodegraded by the consortium. When 4-CP at 100 mg l−1 was fed to the column in open mode operation (20 mg g−1 GAC total supply), up to 27% was immediately available for biodegradation, the rest being adsorbed to the GAC. Biodegradation
continued after the system was returned to closed mode operation, indicating that GAC bound 4-CP became available to the consortium.
Biofilm batch cultures supplied with 10–216 mg 4-CP g−1 GAC suggested that a residual fraction of GAC-bound 4-CP was biologically unavailable. The consortium was able to metabolise
4-CP after perturbations by the addition of chromium (Cr VI) at 1–5 mg l−1 and nitrate at concentrations up to 400 mg l−1. The development of the biofilm structure was analysed by scanning electron microscopy and confocal laser scanning microscopy
(CLSM) techniques. CLSM revealed a heterogeneous structure with a network of channels throughout the biofilm, partially occupied
by microbial exopolymer structures.
Received: 17 March 1999 / Received revision: 27 May 1999 / Accepted: 28 May 1999 |
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