Acidogenic effluents treatment in a yeast reactor

A yeast reactor was proposed to treat highly concentrated acidified effluents of the food industry. The strain Candida utilis was selected and operated in batch or continuously in a perfectly mixed reactor with acetic acid, propionic acid or butyric acid as the sole carbon source while the pH was maintained at 3.5 to prevent most bacterial contamination. The obtained 97% TOC abatement through the continuous reactor was independent of inlet concentration and space-time if the space-time is higher than a critical wash-out value. Such large loading rates as 30 kg TOC/m3•day could be treated. The reaction rate was inhibited by the substrate concentration which explained a steady outlet TOC concentration when the reactor was operated under the critical space-time value. The sludge production was of the same order of magnitude as in a conventional activated sludge reactor. The solids were easily flocculated and settled after neutralizing the suspension.