Keywords: sewage treatment, rotating biological contactors, reed beds, compliance, consent, tertiary treatment, fatigue
Design principles to achieve a robust sewage treatment process using rotating biological contactors and reed beds
Severn Trent Water Ltd. has chosen to adopt rotating biological contactors (RBCs) and reed beds amongst other technologies for treating sewage where the population is less than 2000. The design of an RBC to achieve a fully compliant effluent can be difficult when flows are small or the system is combined and an overflow is not permissible. In addition, RBCs have been plagued by mechanical problems since their conception in the 1960s resulting in short life and high maintenance costs. The paper addresses the issues required to produce a fully compliant high quality effluent employing RBCs and reed beds and the design and quality control requirements to achieve a new generation of RBCs with a guaranteed 20-year maintenance free life.