2. A water treatment plant having an average daily flow rate of 53 MGD (MGD = million gallons per day) adds lime during softening at a dosage of 220 mg/L. Calculate the mass of lime in metric tons/c that must be supplied each day.

A centrifuge dewaters digested sludge from ananaerobic digester. Pertinent performance data are; raw sludge feed rate to the anaerobicdigester = 60,000 lb/day on a dry solids basis, digester suspended solids removalefficiency = 55 percent, suspended solids concentration in digested sludge fed to thecentrifuge = 5.0 percent by weight, centrifuge cake solids concentration = 30 percent byweight, centrifuge solids capture = 90 percent. Sketch a process flow schematic of the system showing both the digester andcentrifuge and all flowing fluid streams, clearly identify the appropriate control surface(s)for mass balance analyses, and then determine;(i) dewatered sludge mass flow rate (lb/day)(ii) centrate flow rate (gal/day)(iii) centrate suspended solids concentration (mg/l).

For a natural raw water containing the following water quality in the table. Check lecture 05 slides on page 52 to determine how much slaked lime is needed remove all hardness. Atomic weight or molecular Concentration weight (g/mol) 120 mg/L 100 mg/L as CaCO3 25 meg/L Ca2+ 40 Mg2+ HCO3 24 61 O A. 5 meq/L О В. 700 mg-СаСОЗ/L O C. 15 meq/L O D. No lime is needed.

A- An industrial wastewater stream flows at a rate of 13500 m³/d containing 100 mg/L. Suspended solids, ferric sulfate [Fe(SO4)] is used as a coagulant' at a dose of 50 mg/L. a) Assuming that there is very little in water, what is the daily lime dose? b) If the sedimentation tank removes 90% of the inlet solids, what is the daily solids production from the sedimentation tank?