Rotating biological contactor solid contact system for the treatment of wastewater from small communities

In Rotating Biological Contactor (RBC) Waste Water Treatment Plants (WWTP) the fixed film unit effluent quality can be improved by means of a biological refinement system, consisting of an aerated Solid Contact (SC) unit. This process, known as an RBC/SC system, is an alternative to other tertiary treatment systems and can be used with good results in the new WWTPs of small communities and in upgrading existing RBC plants whose effluents no longer respect the established standards. The results of an experimental study on an RBC/SC dual biological system fed with clarified municipal sewage are presented and used to validate a new concept mathematical model of each system's phase behaviour. RBC removal efficiency proved to be near stable for total COD while it tended to decrease for particulate COD at higher load values. The aerated SC phase allowed the overall removal efficiency to be improved; the main advantage was observed in the suspended matter removal increase (averaging 26%), while for total and soluble COD the increases averaged 18 and 17% respectively. (C) 1997 IAWQ. Published by Elsevier Science Ltd.