TREATMENT OF PHENOLIC WASTE-WATER IN RBC REACTOR

The removal performance of phenol in a four-stage cross-flow laborator y-scale rotating biological contactor (RBC) reactor was investigated i n the present study. The impacts of major process and operating variab les, viz. input phenol concentration (PH,), input phenol loading (PH.L ), input hydraulic loading (HL), temperature of wastewater (T), and ro tational speed of discs (omega) on the removal efficiency of the syste m 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 deg rees C was obtained for the biodegradation of phenolic wastewater. On the basis of overall treatment of phenolic wastewater in the RBC react or, the optimal removal performance was noted at the end of the second stage inclusive of the first one. It was observed that the phenol rem oval performance improved at higher input phenol concentrations, while at the increased level of input hydraulic loading, the removal perfor mance worsened. The effect of temperature in improving the removal eff iciency was significant in the temperature range of 13-36 degrees C. T he temperature activity coefficient (theta) value of the VantHoff-Arrh enius equation was computed as 1.04 in the stated range of temperature . The positive role of rotational speed of discs in the treatment of p henolic wastewater was more pronounced in the range of 3.7-10 rpm. The major group of microbes, responsible for the microbial treatment of p henol in the acclimatized concentration up to 420 g m(-3), was identif ied as Pseudomonas and the corresponding species were detected as stut zeri and Putida. (C) 1997 Elsevier Science Ltd.