Improved phenol removal in saline effluents by immobilized bacteria

Phenols are organic and highly toxic compounds commonly found in the effluents of various industries due to their wide range of applications. The inhibitory effect of phenol at high concentrations, as well as the high salinity of industrial effluents, poses a serious challenge for treatment by microorganisms. One of the most common approaches to overcome this problem is the immobilization of phenol-degrading microorganisms. The aim of this study was to study the immobilization effect on the phenol removal efficiency of native Janibacter halotolerant bacterium. For this purpose, mica was used as a carrier for bacterial immobilization and the protein concentration assay was applied to determine the immobilization efficiency. The phenol removal by free and immobilized cells was studied as well as the effect of different parameters on phenol removal efficiency. The immobilization efficacy on mica was %68.75, based on protein concentration measurements. The removal time of 100 mg/L phenol by suspended cells was 88 h, while the immobilized cells degraded it in 40 h. Immobilized cells, unlike free cells, were able to remove phenol at lowered temperatures up to 16℃ , salt concentrations greater than 7/5%, and pH levels below 7/5 and above 8/5. Similar results regarding the superior performance of immobilized cells have been obtained in other studies. As a result, the immobilization process considerably improves the efficiency of phenol removal and makes the cells resistant to harsh environmental conditions by protecting the cells from the toxic effects of phenol.