Treatment Of Phenolic Wastes Research Articles

Effect of the Operating Conditions on the Oxidation Mechanisms in Conductive-Diamond Electrolyses

The electrochemical window of conductive-diamond electrodes is large enough to produce hydroxyl radicals with high efficiency, and this species seems to be directly involved in the oxidation mechanisms that occur on diamond surfaces. To verify the role of these radicals in the conductive-diamond electrolyses of organic and inorganic aqueous solutions, several experiments were carried using two well-known processes, which were selected as models: the electrosynthesis of peroxodiphosphate and the treatment of phenolic wastes in sulfate supporting media. Results show that there is an abrupt change in the efficiencies and product conversions of the processes with the anodic potential, although there is no change in the nature of the reaction intermediates or final products. Working at high anodic potentials led to very efficient processes in both cases. The changes observed have been interpreted in terms of the oxidation mechanisms involved in the process, taking into account the contribution of hydroxyl radicals for higher potentials and the formation of stable oxidants through the oxidation of the electrolyte by these radicals.

Biological treatment of phenolic wastes: Comparison between free and immobilized cell systems

Phenol degradation by free and immobilized cells ofFusarium flocciferum was studied in a chemostat at steady-state conditions. For the free cell system the dilution rates varied from 0.02 to 0.13h−1, with a total phenol removal up to 0.08h−1. Wash-out seemed to set in at 0.11h−1. The immobilized cells showed virtually complete phenol utilization at 1g/l, over a period of four months. At D=0.2h−1 and above 1g/l phenol, the complete phenol removal is not achieved: a progressive increase in the outlet concentration was observed attaining a value of 284mg/l at 1.5g/l.

Treatment of phenolic wastes in an aerated submerged fixed-film (ASFF) bioreactor

The biological removal of phenol was studied in a multi-stage fixed-film reactor at phenol concentrations in the range of 190–900 mg l −1, hydraulic loadings of 0.02–0.22 m 3 m −2 day −1 and temperatures of 20–35°C. Phenol removals up to 99.9% were obtained at 20°C but the efficiency decreased as the loading rate or phenol concentration was increased. The reactor coped with organic overloads better than with hydraulic overloads. Removal efficiencies increased as temperature was increased. Reactor performance was stable under extreme loadings and the reactor was capable of handling a ten-fold increase in loading with less than 20% loss in phenol removal efficiency. A large amount of attached biomass was retained in the reactor and was mostly present in the first stage where the majority of organic removal occurred.

Denitrification kinetics in the treatment of phenol wastes in a single‐sludge system

Abstract Denitrification kinetics parameters are evaluated for a phenol carbon source. Batch and continuous anoxic‐aerobic lab‐scale plant test results are compared.

Microbiological factors in the treatment of phenolic wastes.

Microbiological factors in the treatment of phenolic wastes.