PERFORMANCE OF AN ANAEROBIC ROTATING BIOLOGICAL CONTACTOR - EFFECTS OF FLOW-RATE AND INFLUENT ORGANIC STRENGTH

The system performance of an anaerobic relating biological contactor ( AnRBC) for the treatment of high-strength synthetic wastewater was inv estigated under different flow rates and influent organic strengths. I n the steady-state condition, the removal efficiencies of COD and BOD increased as the hydraulic retention time (HRT) increased or the influ ent organic strength decreased. The overall COD removal efficiencies r anged from 74 to 82% at an HRT of 32 h, from 56 to 61% at an HRT of 16 h, and from 44 to 53% at an HRT of 8 h. In view of these results, it was concluded that the AnRBC reactor is an effective treatment process at an HRT of 32 h and influent COD between 3248 and 12150 mg l(-1). M ost organic compounds were removed in the first two stages of the AnRB C indicating that a two-stage reactor may be sufficient in practical a pplications. The microscopic observations showed that the acetogenic m icroorganisms were predominant in the first two stages while the metha nogenic microorganisms were predominant in the last two stages. The ex perimental observations were confirmed by performing a theoretical eva luation of the steady-state biofilm thickness, the mass balance analys is and the methane production to allow insight into the performance of an AnRBC process. (C) 1997 Elsevier Science Ltd.