Resolving the reliability issues of Rotating Biological Contractors

Rotating Biological Contactors (RBC) are capable of producing is very high quality effluent and perhaps much better than alternative small works processes. Where the demand for effluent quality is high an RBC is worthy of serious consideration and may be the correct choice from a process point of view. Restricting use of RBCs limits the engineer's ability to produce a cost effective process.They have however been out-of-favour for many years because of their lack of mechanical reliability. There has almost been a tendency to blame the process for the mechanical instability rather than to recognise that the problem is of an Engineering nature, which can be relatively easily resolved. This paper presents background information on the mechanical deficiencies of early generation equipment, the process taken by Cranfield University and Severn Trent in evaluating those deficiencies and the development of a 20-year life design. The economic viability of the resulting design is demonstrated through the presentation of life-cycle costs for the two designs.