Interpolation ??? A treatment plant consists of a primary sedimentation tank followed by a trickling filter that removes 80% of the influent BOD. The flow is then directed to a constructed marsh system that has an influent target BOD concentration of 30 mg/l before being discharged to a small stream. Using the following table of % BOD removal to overflow rate and calculate the dimensions of a circular sedimentation tank suitable for the imposed flow with a detention time of 1.5 hours. Assume BOD and flow of wastewater entering the plant to be 214.245 mg/l and 848 kL/day. BOD Removal % 22.0 31.5 33.5 35.5 36.5 37.5 Overflow rate m3/m2/day 100 50 40 30 25 20 How do I find the value of overflow rate when the BOD removal percentage is 80% from this table? Do I use interpolation ? I'm not sure on how to use interpolation. Thanks Stacy.