SEDIMENTATION FILTRATION CE 326 Principles of Environmental

SEDIMENTATION & FILTRATION CE 326 Principles of Environmental Engineering Iowa State University Department of Civil, Construction, and Environmental Engineering Tim Ellis, Associate Professor March 6, 2009

Announcements Ø Jar test and Chlorination Lab due today by 5 pm Ø Next week field trip to Ames Water Plant Ø 2 nd exam tentatively scheduled for Friday, March 27 th

SEDIMENTATION ( cont’d)

Definitions Filtration: A process for separating s_______ and c _______ impurities from water by passage through a p______ medium, usually a bed of s_____. Ø Most particles removed in filtration are much s_______ than the p____ s____ between the sand grains, and therefore, adequate particle d________ (coagulation) is extremely important. Ø

Filtration Spectrum SCANNING ELECTRON MICROSCOPE MACRO MOLECULES MICRO PARTICLES MOLECULES IONS OPTICAL MICROSCOPE VISIBLE TO NAKED EYE MACRO PARTICLES MICRON Angström Molecular weight Sugars Viruses Algae and protozoans Dissolved salts Bacteria Pesticides Colloids Metal ions Sands Humic acids Reverse Osmosis Microfiltration Nanofiltration Ultrafiltration Note : 1 Angström = 10 -10 meter = 10 -4 micron CONVENTIONAL FILTRATION

Performance Ø The influent t_____ ranges from 1 - 10 NTU (nephelometric turbidity units) with a typical value of 3 NTU. Effluent turbidity is about ______ NTU.

Media Ø Medium SG Ø sand 2. 65 Ø anthracite 1. 45 - 1. 73 Ø garnet 3. 6 - 4. 2

History Ø S s filters were introduced in low and 1804: Ø sand diameter Ø depth Ø loading rate 0. 2 mm 1 m 3 - 8 m 3/d·m 2 /d

Slow Sand Filters S __________ - gelatinous matrix of bacteria, fungi, protozoa, rotifera and a range of aquatic insect larvae. Ø As a Schmutzdecke ages, more a____ tend to develop, and larger aquatic organisms may be present including some bryozoa, snails and annelid w______. Ø

http: //water. shinshu-u. ac. jp/e_ssf_link/usa_story/12 Someyafilteralgae. jpg

apid Ø R sand filters were introduced about 1890: Ø effective size Ø uniformity coef. Ø depth Ø loading rate 0. 35 - 0. 55 mm 1. 3 - 1. 7 0. 3 - 0. 75 m 120 - 240 m 3/d·m 2 /d

Ø D m filters introduced about 1940: ual edia Ø Ø Depth: anthracite (coal) sand loading rate 0. 45 m 0. 3 m 300 m 3/d·m 2 /d

Pathogen Removal During Filtration Ø poliovirus removal with filtration but without coagulation: 1 -50% Ø poliovirus removal with filtration and with coagulation: 90 -99% Ø Cryptosporidium oocysts removal with filtration without coagulation: 90%

Operation Backwash Filtration Backwash water out Fluidized Filter Media Underdrain Support Filtered Water Backwash Water

Particle Removal Mechanisms Ø Gravity Ø Inertial Ø Interception Ø Diffusion

Inertia

Particle Removal Mechanisms

Ideal Filter Run Filter Ripening Period (Turbidity < 0. 1 NTU in 15 min) Terminal Head loss

Non-Air-Scouring Underdrain 26

Non-Air-Scouring Underdrain 27

Non-Air-Scouring Underdrain 28

Wheeler Block

Air-Scouring Underdrain 30

Leopold Type S™ Technology Underdrain 31

Air-Scouring Underdrain 32

Bachwash Efficiency • 5 nozzles/ft 2 or 55 nozzles/m 2 - acceptable • < 4 nozzles/ft 2 or 40 nozzles/m 2 – large dead zones • 24 nozzles/ft 2 or 268 nozzles/m 2 good 33

Automatic Backwash Filter

Automatic Backwash Filter

first elevated steel water tank west of the Mississippi River Ø erected in 1897 under the supervision and design of Anson Marston Ø constructed due to a severe water shortage in 1895 that required cancellation of classes Ø tank holds 162, 000 US gallons Ø 1978, the water tower was disconnected when the university switched to municipal water Ø

Water Towers, 1951 -1970, Water District No. 54 Located on the north side of the Des Moines Field House, near the current skateboard park

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. Stanton, Iowa - 96 feet tall. - holds 2, 400, 000 cups of coffee (150, 000 gals. ) - completed in time for Homecoming 2000.

Atlanta, Illinois Helm, California Markle, Indiana Adair, Iowa Ironwood, Michigan