Upload
derek-sanders
View
217
Download
0
Embed Size (px)
Citation preview
FILTRATIONFILTRATIONCE326 Principles of Environmental EngineeringCE326 Principles of Environmental Engineering
Iowa State UniversityIowa State UniversityDepartment of Civil, Construction, and Department of Civil, Construction, and
Environmental Engineering Environmental Engineering Tim Ellis, Associate ProfessorTim Ellis, Associate Professor
March 7, 2008March 7, 2008
DefinitionsDefinitions
Filtration: A process for separating s_____________ and c ______________ impurities from water by passage through a porous medium, usually a bed of sand. Most particles removed in filtration are much smaller than the pore size between the sand grains, and therefore, adequate particle d______________ (coagulation) is extremely important.
Filtration SpectrumFiltration Spectrum
Ultrafiltration CONVENTIONAL FILTRATION
Sands
Algae and protozoans
Bacteria
Colloids
Humic acids
Metal ions
Pesticides
Dissolved salts
Sugars
Molecularweight
Viruses
Angström
MICRON
IONSIONS MOLECULESMOLECULES MACRO MOLECULESMACRO MOLECULESMICRO PARTICLESMICRO PARTICLES MACRO PARTICLESMACRO PARTICLES
VISIBLE TO NAKED EYEVISIBLE TO NAKED EYEOPTICAL MICROSCOPEOPTICAL MICROSCOPESCANNING ELECTRON MICROSCOPESCANNING ELECTRON MICROSCOPE
Note : 1 Angström = 10-10 meter = 10-4 micron
Reverse Osmosis
Nanofiltration
Microfiltration
PerformancePerformance
The influent t__________ ranges from 1 - 10 NTU (nephelometric turbidity units) with a typical value of 3 NTU. Effluent turbidity is about ______ NTU.
MediaMedia
Medium SG sand 2.65 anthracite 1.45 - 1.73 garnet 3.6 - 4.2
HistoryHistory
S s filters were introduced in 1804:
sand diameter 0.2 mm depth 1 m loading rate 3 - 8 m3/d·m2
low and
Slow Sand FiltersSlow Sand Filters S ___________________
- gelatinous matrix of bacteria, fungi, protozoa, rotifera and a range of aquatic insect larvae.
As a Schmutzdecke ages, more algae tend to develop, and larger aquatic organisms may be present including some bryozoa, snails and annelid worms.
http://water.shinshu-u.ac.jp/e_ssf/e_ssf_link/usa_story/12Someyafilteralgae.jpg
R sand filters were introduced about 1890:
effective size 0.35 - 0.55 mm uniformity coef. 1.3 - 1.7 depth 0.3 - 0.75 m loading rate 120 - 240
m3/d·m2
apid
D m filters introduced about 1940: Depth: anthracite (coal) 0.45 m sand 0.3 m loading rate 300 m3/d·m2
ual edia
Operation Operation
FiltrationFiltration BackwashBackwash
Filter Media
Filtered Water
Fluidized Filter Media
Backwash Water
Backwash water out
Underdrain Support
Particle Removal MechanismsParticle Removal Mechanisms
GravityGravity InertialInertial InterceptionInterception DiffusionDiffusion
InertiaInertia
Particle Removal MechanismsParticle Removal Mechanisms
0.1 1 10 1000.1
1
10
100BrownianInterceptionGravityTotal
Particle Diameter (m)
Par
ticle
rem
oval
as
pC*
Ideal Filter RunIdeal Filter Run
Terminal Head loss
Filter Ripening Period(Turbidity < 0.1 NTU in 15 min)
Non-Air-Scouring Non-Air-Scouring UnderdrainUnderdrain
20
Non-Air-Scouring Non-Air-Scouring UnderdrainUnderdrain
21
Non-Air-Scouring Non-Air-Scouring UnderdrainUnderdrain
22
Wheeler Wheeler BlockBlock
Air-Scouring Air-Scouring UnderdrainUnderdrain
24
Leopold Type S™ Technology Leopold Type S™ Technology UnderdrainUnderdrain
25
Air-Scouring Air-Scouring UnderdrainUnderdrain
26
Bachwash Bachwash EfficiencyEfficiency
27
• 5 nozzles/ft2 or 55 nozzles/m2 - acceptable
• < 4 nozzles/ft2 or 40 nozzles/m2 – large dead zones
• 24 nozzles/ft2 or 268 nozzles/m2 - good
Automatic Backwash FilterAutomatic Backwash Filter
Automatic Backwash FilterAutomatic Backwash Filter
Water Towers, 1951-1970, Water District No. 54Located on the north side of the Des Moines Field House, near the current skateboard park
Stanton, Iowa- 96 feet tall.- holds 2,400,000 cups of coffee (150,000 gals.) - completed in time for Homecoming 2000.
Hollywood screen and TV personality Virginia Christine, "Mrs. Olson" of coffee commercial fame, was one of Stanton's famous daughters. At the time of our centennial in 1970, Virginia came home to be our parade marshal. During the celebration she served coffee to the public. Stanton's water tower was converted to a giant Swedish coffeepot the following year.
Adair, IowaHelm, CaliforniaAtlanta, Illinois
Markle, Indiana Ironwood, Michigan