Treatment of phenolic wastewater in RBC reactor

The removal performance of phenol in a four-stage cross-flow laboratory-scale rotating biological contactor (RBC) reactor was investigated in the present study. The impacts of major process and operating variables, viz. input phenol concentration (PH,), input phenol loading (PH.L), input hydraulic loading (HL), temperature of wastewater (T), and rotational speed of discs (omega) on the removal efficiency of the system were examined. A first-order reaction with an average rate constant (K-c) value of 0.10-0.13 h(-1) at a temperature range of 20.5-27.0 degrees C was obtained for the biodegradation of phenolic wastewater. On the basis of overall treatment of phenolic wastewater in the RBC reactor, the optimal removal performance was noted at the end of the second stage inclusive of the first one. It was observed that the phenol removal performance improved at higher input phenol concentrations, while at the increased level of input hydraulic loading, the removal performance worsened. The effect of temperature in improving the removal efficiency was significant in the temperature range of 13-36 degrees C. The temperature activity coefficient (theta) value of the VantHoff-Arrhenius equation was computed as 1.04 in the stated range of temperature. The positive role of rotational speed of discs in the treatment of phenolic wastewater was more pronounced in the range of 3.7-10 rpm. The major group of microbes, responsible for the microbial treatment of phenol in the acclimatized concentration up to 420 g m(-3), was identified as Pseudomonas and the corresponding species were detected as stutzeri and Putida. (C) 1997 Elsevier Science Ltd.