Mechanical redesign of the rotating biological contactor

The principle of the Rotating Biological Contactor (RBC) was originated in the early part of the century and today there are many thousands of units operating world wide. However, the RBC has been plagued with mechanical deficiencies since its conception. This paper presents a brief insight into some of the major mechanical defects associated with RBCs. These findings have been accumulated over the past three years during a mechanical design audit, and encompass over two hundred and sixty RBC units visited operating on site. The reasons for mechanical failures are attributed to poor engineering design, low frequency corrosion fatigue and microbiologically influenced corrosion; evidence supporting these claims is presented. Having the benefit of a thorough understanding of the mechanisms and reasons for mechanical failure, a new approach to designing RBCs is encouraged. This has resulted in a new generation of RBC designs with a guaranteed operational life of twenty years.