Page 427 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

382 Fundamentals of Water Treatment Unit Processes: Physical, Chemical, and Biological

show the filter box, in a drawing, (b) to select the Figure 12.46 was provided by Sylvie Roy, communica-
headloss advisable for normal operation, and (c) to tions and marketing manager, Infilco Degremont, Richmond,
estimate the headloss required for the backwash. Virginia, and was used with permission.
12.9 Headloss to Expand Bed of A Rapid Filter
Given APPENDIX 12.A: FILTRATION IN NEW YORK
A bed of sand has d ¼ 400 mm and e 0.40.
A distinguishing aspect of civil engineering projects is the
Required
role of political factors, in the sense that various kinds of
Calculate Dh for incipient fluidization.
values are represented and must come to bear in the decision
12.10 Scenario Explorations by Mathematical Modeling
making. The history of the New York water supply is an
Using Spreadsheet
interesting case study (see Gibson, 1982, p. 25) that illustrates
Given
this idea.
From a pilot plant study, the filter coefficient, l, was The drama started with Aaron Burr, who as a state assem-
determined as, l ¼ 0.06 cm 1
blyman, wrote a bill, ‘‘An Act for supplying the City of New
Other conditions. York with a pure and wholesome water.’’ Foreseeing a
. Media is anthracite, d 10 ¼ 1.1 mm
surplus of funds, Burr organized the Manhattan Company,
. Porosity, P ¼ 0.40 which was then given the charter in 1799 by the legislature
. HLR ¼ 5gpm=ft 2
to supply New York City with wholesome water. The Man-
. Temperature, T ¼ 208C
hattan Company would use the surplus capital from the water
. r(floc) 1.05 g=cm 3
works financing to start a new bank to compete with the
. d(floc) can range from 1 to 300 mm, depending
Federalist’s banks associated with Alexander Hamilton.
on coagulant dosage, rapid mix, flocculation fac- Instead of bringing in outside water, presumably from the
tors (flocculation may be bypassed if desired) Bronx River, the company sunk more wells into the polluted
Required aquifer. The bank became the Chase-Manhattan and later,
Explore design by mathematical modeling using the c. 2005, Chase.
theory outlined. An objective is about 2–3 log removal The Manhattan Company essentially tied the hands of
as measured by turbidity and=or particles. anyprogresstowardasatisfactory watersupplyand so
(a) Explore the feasibility of a deep filter bed, such nothing was done until after 1830. Finally, in October
as 3–4m. 1842, water from the Croton River was delivered to New
(b) Explore the feasibility of a high HLR. York with a maximum flow of 95 mgd (this system
(c) Ascertain the effect of floc particle size on per- was later called ‘‘Old Croton’’). Then in 1893, the ‘‘New
formance and your recommendation for the Croton’’ was completed with an aqueduct capacity of
resulting design. 302 mgd. When added to the 28 mgd Bronx River conduit,
Show plots as appropriate. completed in 1885, the total conduit capacity was 425 mgd
(Wegmann, 1896, p. iii).
George Warren Fuller entered the picture on May 23,
ACKNOWLEDGMENTS 1906, when the Board of Estimate engaged Fuller and
Rudolph Hering to investigate the Croton water supply and
Kevin Gertig, supervisor, Fort Collins Water Treatment to prepare plans for filter construction (Fuller, 1914, p. 152).
Plant, was available for consultation at any time and clarified Their recommendations, in an October 30, 1907 report, was to
points regarding plant operation. Grant Williamson-Jones, build 42 acres of slow sand filters at Jerome Park (the site of a
City of Fort Collins, Colorado, provided the photo micro- major reservoir for the Croton water), superposed on a fil-
graph of floc-media grains. tered-water reservoir. According to Fuller (p. 153),
The City of Bellingham, Public Works Department, Ted
Carlson, director, granted permission (2010) to use photo- This project was pigeonholed, very likely because the panic of
graphs and other material from their water treatment facility, that year and the difficulty of selling bonds made public
including Figures 12.25, 12.27, and 12.41. The department improvements of this character impractical.
also granted permission to use water quality data from the
plant for Problems 2.5 and 2.6 of the Solutions Manual. Then on May 18, 1911, an appropriation of $8,690,000
Carol Sosak, marketing coordinator, ITT Water & Waste- was made by the Board for construction of the Jerome Park
water Leopold, Inc., F Zelienople, Pennsylvania, granted per- Filters. Plans for construction were made under the direction
mission to use graphics taken from ITT Leopold materials. of Fuller as consulting engineer and the chief engineer and
Sherry Morrison, senior administrative assistant, Publishing division engineer for the City. The procedure involved com-
Group, American Water Works Association, Denver arranged paring the relative merits and costs of slow sand and ‘‘mech-
for permission to use Figures 12.3 through 12.5, and 12.41b. anical’’ filters, based on a filtered water flow of 320 mgd. In a
Figure12.5wasfromthe filesofKurtKeeley,databasemanager, report of May 21, 1912, Fuller recommended mechanical
American Water Works Association, Denver, Colorado. filters,