Continuous aerobic phenol degradation by defined mixed immobilized culture in packed bed reactors

Abstract

A defined mixed culture of Pseudomonas putida, Commamonas testosteroni and Candida tropicalis was immobilized by adsorption on polyurethane foam, cocoa-fibers, expanded slate and sintered glass. Packed bed reactors were used for long-term continuous phenol biodegradations. Loading experiments were done to study the impact of the following parameters: (1) hydraulic retention time, (2) dissolved oxygen concentration, and (3) elimination of the oxygen limitation. After the acclimation period (approximately 10 d), the loading test with the individual packings showed the following maximum degradation rates: sintered glass 34, polyurethane foam 12, expanded slate 11.5, and cocoa-fibers 7.7 kg m(-3) d(-1). All these values were reached at a removal efficiency >99 % and with oxygen in excess. Under these conditions, the pH of the diluted unbuffered medium in the reactor effluent was 3.2-4.0 and no incompletely oxidized metabolic intermediates were found. The free cell concentration in the effluent increased after the phenol overloading time period.

Simple models for the continuous aerobic biodegradation of phenol in a packed bed reactor

“…The following packing materials were used: polyurethane foam, porous glass balls and cocoa fibres. An enriched mixed microbial culture (Pseudomonas putida S7, Comamonas testosteroni Pb50 and Candida tropicalis Ct2) served as a catalyst for the phenol degradations (Páca Jr. et al, 2005 The measured parameters were: the phenol concentrations at inlet and outlet, temperature, pH and dissolved oxygen tension in the water outflow, together with the volumetric flow-rates of water and air. The loading characteristics were tested.…”

The emerging threat antifungal-resistant Candida tropicalis in humans, animals, and environment

“…The authors suggested that the presence of these yeasts in coastal environments may have led to the overexpression of efflux pumps, which may explain the high MICs values found on several drugs (azoles and amphotericin B). Another relevant biologic characteristic of C. tropicalis is its ability to tolerate and degrade phenol ( Páca et al., 2005 ; Wang et al., 2011 ). Indeed, phenol is an aromatic compound applied in the production of pesticides, antiseptics, slimicides, and medicinal preparations ( Mishra and Kumar, 2019 ), and is considered a marker of environmental pollution ( Montaño et al., 2013 ).…”

Respirometry kinetics of phenol oxidation by Comamonas testosteroni Pb50 under various conditions of nutritional stress

“…This strain was isolated from a biofilm developed on polyurethane foam particles of a packed bed reactor after 4 months of continuous phenol degradation (Paca Jr. et al, 2005). The strain was able to utilize phenol, toluene, xylenes, styrene, and acetone as the sole carbon and energy sources.…”