There is, however, a reasonable relationship between turbidity and total suspended solids for the settled and filtered secondary effluent from the activated sludge roce The conservation factors for settled secondary effluent and for secondary effluent filtered with a granular-medium depth filter will typically vary from 2. 3 to 2. 4 and 1.3 to respectively However, turbidity readings at a given facility can be used for process control. Some on line turbidity meters used to monitor the performance of microfiltration units are affected by the air used to clean the membranesThere is, however, a reasonable relationship between turbidity and total suspended solids for the settled and filtered secondary effluent from the activated sludge process. The conservation factors for settled secondary effluent and for secondary effluent filtered with a granular-medium depth filter will typically vary from 2.3 to 2.4 and 1.3 to 1.6, respectively. However, turbidity readings at a given facility can be used for process control. Some on line turbidity meters used to monitor the performance of microfiltration units are affected by the air used to clean the membranes