Practice Math Problems Questions

A centrifuge is being fed with waste activated sludge at 0.12 MGD. The sludge TSS is 15,000 mg/L. The polymer target dose is 12 lb ACTIVE polymer per dry ton (DT) of TSS fed. The polymer make-down solution is 2.0% ACTIVE polymer by weight and has a specific gravity (SG) of 1.04. Extraneous data: centrifuge cake averages 18% solids and centrate is 400 mg/L TSS. Calculate the required polymer feed pump rate in mL/min. Use: lbs/day = (mg/L) × (MGD) × 8.34; 1 DT = 2,000 lb; weight of water = 8.34 lb/gal; solution lb/gal = 8.34 × SG; 1 gal = 3,785 mL; 1 day = 1,440 min.