Performance of an anaerobic rotating biological contactor: Effects of flow rate and influent organic strength

The system performance of an anaerobic rotating biological contactor (AnRBC) for the treatment of high-strength synthetic wastewater was investigated under different flow rates and influent organic strengths. In the steady-state condition, the removal efficiencies of COD and BOD increased as the hydraulic retention time (HRT) increased or the influent organic strength decreased. The overall COD removal efficiencies ranged 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. Most organic compounds were removed in the first two stages of the AnRBC indicating that a two-stage reactor may be sufficient in practical applications. The microscopic observations showed that the acetogenic microorganisms were predominant in the first two stages while the methanogenic microorganisms were predominant in the last two stages. The experimental observations were confirmed by performing a theoretical evaluation of the steady-state biofilm thickness, the mass balance analysis and the methane production to allow insight into the performance of an AnRBC process.