a two stage airobitic design factor is used to treat a combi

a two stage airobitic design factor is used to treat a combined primary and secondary stage the hydraulic detention time is
a) less than solid retention time
b) greater than solid retention time
c) equal tosolid retention time
d) not important in design

Solution

Option B is correct. It will be greater than solid retention time. Because time required for combined primary and secondary treatment is more than single stage treatment which is single solid retention time. Hence it is more than solid retention time.