SEWAGE-TREATMENT FOR SMALL COMMUNITIES - THE SEVERN TRENT APPROACH

When faced with the requirement to refurbish or upgrade a large number of small sewage-treatment works, Severn Trent Water standardized proc ess selection on rotating biological contactors and, where higher stan dards of effluent were demanded, constructed reed beds. These systems are described and costs are presented and discussed. Performance data from rotary biological contactors and reed-bed sites are used to illus trate the additional security provided by the reed beds. Results from a survey of a reed bed treating a storm-sewage overflow are shown for a storm event.