Reuse of biologically regenerated activated carbon for phenol removal

Granular biologically activated carbon (GBAC) is in principle suited for removal of phenolic substrate from wastewater. In this study a wastewater model was used and special attention was paid to the operation of separate aerobic bioregeneration of carbon and reuse of bioregenerated carbon in a new stage of the experiment. In order to assess the effectiveness of bioregeneration, the efficiency of the biosorption system both before and after its bioregeneration was monitored at the substrate concentrations ranging from 1.9 to 1053 mg l−1. All kinetic parameters for the biosorption system were determined for both fresh and already used GBAC. A 92–100% efficiency of phenol removal was achieved irrespective of whether the fresh or bioregenerated GBAC was used. The process of bioregeneration for the once-used GBAC was faster than for the one that was used several times. It was also faster when phenol alone was used as substrate than in the case of a phenol mixture. Respirometric measurements indicated that a mixture of substituted phenols showed inhibition effects on microorganisms. Calculations based on these measurements, as well as the findings of GC/MS analysis, indicated that deterioration of the adsorbent quality was taking place continuously. It was concluded that bioregeneration, carried out as a separate operation, could not be recommended for practice.