CE 326 Principles of Environmental Engineering
Department of Civil, Construction and Environmental Engineering
Iowa State University
March 3, 2008
Tim Ellis, Ph.D., P.E.
Fig 4-8: Flow Diagram of conventional surface water treatment plant (“filtration plant”)
Fig 4-8: Flow diagram of water softening plant
Coagulation = Charge reductionFlocculation = Contact of particles
Fig 4-10: Effect of salt on electric potential
Fig 4-11: Effect of valence on electric potential
Fig 4-13: results from jar test
Alkalinity in CoagulationNeeded to neutralize acid formed
Paddle Mixer Details
Paddle Mixers in Left Chamber and Flocculators in Right Two Chambers
Fig 4-35: Settling in an upflow clarifier
Fig 4-32: Zones of sedimentation on a horizontal flow clarifier
Fig 4-37: Partial solids removal in ideal sedimentation tank
Let’s say v0 = 0.20 mm/sWhat % removal for particles with settlingvelocity = 0.15 mm/s?
Fig 4-43: Typical gravity filter box
Fig 4-44: Operation of rapid sand filter
Manual Control Panel in Water Treatment Plant
Lime slaker and feed system.
Upflow solids contact tank. Effluent weir on right.
Settling tank with radial weirs
Rapid sand filter with exposed under drain block.Wash water troughs run from left into gullet on right.
Rapid sand filter with water level just below backwash troughs. Note iron stain at high water line.
Rapid sand filter during filtration.Reflection shows water level above gullet and backwash troughs.
Rotameter used to measure flowrate of gaseous chlorine into water.
Hydrofluorosilicic acid drum and pump metering system for feeding fluoride into water.
Softening sludge lagoon. Winter view shows ice (light blue) where supernatant water is stnading.
Overview of water treatment plant showing sludge lagoons and building housing treatment facilities.