Water TreatmentWater Treatment

CE 326 Principles of Environmental EngineeringCE 326 Principles of Environmental Engineering

Department of Civil, Construction and Environmental EngineeringDepartment of Civil, Construction and Environmental Engineering

Iowa State UniversityIowa State University

March 3, 2008March 3, 2008

Tim Ellis, Ph.D., P.E.Tim Ellis, Ph.D., P.E.

Fig 4-8:Fig 4-8: Flow Diagram of conventional surface Flow Diagram of conventional surface water treatment plant (“filtration plant”)water treatment plant (“filtration plant”)

Fig 4-8:Fig 4-8: Flow diagram of water softening plant Flow diagram of water softening plant

Coagulation = Charge reductionCoagulation = Charge reductionFlocculation = Contact of particlesFlocculation = Contact of particles

Fig 4-10:Fig 4-10: Effect of salt on electric potential Effect of salt on electric potential

Fig 4-11:Fig 4-11: Effect of valence on electric potential Effect of valence on electric potential

Fig 4-13:Fig 4-13: results from jar test results from jar test

Alkalinity in CoagulationAlkalinity in Coagulation

Needed to neutralize acid formedNeeded to neutralize acid formed

Paddle Mixer DetailsPaddle Mixer Details

Paddle Mixers in Left Chamber Paddle Mixers in Left Chamber and Flocculators in Right Two Chambersand Flocculators in Right Two Chambers

Fig 4-35:Fig 4-35: Settling in an upflow clarifier Settling in an upflow clarifier

Fig 4-32:Fig 4-32: Zones of sedimentation on a horizontal flow Zones of sedimentation on a horizontal flow clarifierclarifier

Q

VQ

V

h

time

depthvs

h

time

depthvs

V

hQ

QVh

vs V

hQ

QVh

vs

wlhhQ

vs wlhhQ

vs

os vA

Qv os v

A

Qv

Fig 4-37:Fig 4-37: Partial solids removal in ideal sedimentation tank Partial solids removal in ideal sedimentation tank

o

s

v

vP 100

o

s

v

vP 100

Let’s say vLet’s say v00 = 0.20 mm/s = 0.20 mm/s

What % removal for particles with settlingWhat % removal for particles with settlingvelocity = 0.15 mm/s?velocity = 0.15 mm/s?

%7520.0

15.0100 P %75

20.0

15.0100 P

Fig 4-43:Fig 4-43: Typical gravity filter box Typical gravity filter box

Fig 4-44:Fig 4-44: Operation of rapid sand filter Operation of rapid sand filter

Manual Control Panel in Water Treatment PlantManual Control Panel in Water Treatment Plant

Lime slaker and feed system.Lime slaker and feed system.

Upflow solids contact tank. Upflow solids contact tank. Effluent weir on right.Effluent weir on right.

Settling tank with radial weirsSettling tank with radial weirs

Rapid sand filter with exposed under drain block.Rapid sand filter with exposed under drain block.Wash water troughs run from left into gullet on right. Wash water troughs run from left into gullet on right.

Rapid sand filter with water level just below backwash Rapid sand filter with water level just below backwash troughs. Note iron stain at high water line.troughs. Note iron stain at high water line.

Rapid sand filter during filtration.Rapid sand filter during filtration.Reflection shows water level above gullet and backwash troughs.Reflection shows water level above gullet and backwash troughs.

Rotameter used to measure flowrate of gaseous chlorine into Rotameter used to measure flowrate of gaseous chlorine into water.water.

Hydrofluorosilicic acid drum and pump metering system for Hydrofluorosilicic acid drum and pump metering system for feeding fluoride into water.feeding fluoride into water.

Softening sludge lagoon. Winter view shows ice (light blue) Softening sludge lagoon. Winter view shows ice (light blue) where supernatant water is stnading.where supernatant water is stnading.

Overview of water treatment plant showing sludge lagoons Overview of water treatment plant showing sludge lagoons and building housing treatment facilities.and building housing treatment facilities.