Hi Nick. I agree with others ...
Published by Tim Acland, Anglian Water 1977-2017
Hi Nick. I agree with others comments that there are very many variables to be considered. However as a general guide for dry weather flow domestic wastewater treatment in a typical 1980's design system includes a reactor retention period at 6-10 hours and a settlement retention period of at least 6 hours. These minimum times will extend depending on effluent treatability and plant configuration and operation. Hope this helps.