Page 175 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

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

6.22 Plate Settler Design 6.27 Design for Andijik WRK III
Given Given=Required
A sedimentation basin is comprised of plate settlers. For the Andijik WRK III WTP in Holland, determine
the plan area required showing plate arrangement and
Assume
hydraulic flows.
. L(plate) ¼ 100 cm long.
6.28 Particle Sizes Removed by Plate Settlers at Andijik
. d(plates) ¼ 6.0 cm.
WRK III
. Suspension has characteristics shown in Figure 6.18.
Given=Required
Required
For the Andijik WRK III WTP in Holland, estimate the
Determine the effect on performance if the plates are
smallest size of particles that will be removed com-
150 cm long (instead of 100 cm).
pletely. Determine the plan area required showing
6.23 Performance of Plate Settlers in Holland
plate arrangement and hydraulic flows.
Given 6.29 Particle Sizes Removed by Plate Settlers at CSU
Data from Table 6.12 for the Andijik WRK III WTP in WTRPP
Holland is given as an excerpt from the table, i.e.,
Given
The following data pertain to the plate settler system of
a water-treatment pilot plant, c. 1996, at Colorado State
Surface Loading
University:
Flow Rate, SOR
. w(plate) ¼ 1.22 m (4.0 ft)
2
3
3
2
Location (m =s) (mgd) (m =m =day) (gpm=ft ) . L(plate) ¼ 0.61 m (2.0 ft)
. d ¼ 64 mm (2.5 in.)
Andijk WRK III, 4.16 95 38.7 0.66
. Q ¼ 76 L=min (20 gpm)
Holland
. n(cells) ¼ 25
. Temperature varies, 28C T 128C
Required
Required
Estimate the smallest size of alum floc particles that
Estimate the smallest particle size, d(particle), that may
should be removed.
be removed by the plant.
6.24 Reynolds Number Calculation
Given=Required ACKNOWLEDGMENTS
Calculate the Reynolds number for the flow in the
plate cells at the Fort Collins WTP (see Example 6.7). Judy Berkun, manager special projects, Malcolm Pirnie, Inc.,
6.25 Spreadsheet for Plate-Settler Performance Evalu- White Plains, New York, provided the photograph of Allen
ation—Discrete Particles Hazen. Marlene Hobel, vice president, Corporate Communi-
cations, Camp Dresser & McKee (now CDM), Boston,
Given
Massachusetts, provided the photograph of Thomas Camp.
Suppose the particles to be removed by a plate settler
The author appreciates their help.
system are mineral sediments with size distribution as
Steve Comstock, supervisor, Fort Collins WWTP, granted
shown by Figure 6.12.
permission to use the photographs of the sedimentation basin
Required at the Fort Collins plant. Comstock and staff often hosted
Show by plot obtained by spreadsheet the relationship student field trips and individual visits to the plant.
between plan area of plates and the percent removal of
the suspension.
6.26 * Spreadsheet for Plate Settler Performance Evalu- GLOSSARY
ation—Flocculent Particles
(Note: This is a * problem, i.e., more difficult) Center feed clarifier: A settling basin with flow from center
ports and discharge around peripheral overflow
Given
weirs.
Suppose the particles to be removed by a plate-settle-
Clarifier: See settling basin.
rsystem comprise a flocculent suspension characterized
Dead zone: A region of a flow field in which there is little
by Figure 6.14 (and Figure 6.18 of Problem 6.22).
participation in the main flow and the exchange with
Required the main flow is small.
Show by plot obtained by spreadsheet the relationship Detention time: Basin volume divided by flow, i.e., T ¼
between plan area of plates and the percent removal of V(basin)=Q.
the suspension. Provide your own rationale on how to Discrete particle: A particle with fixed size.
take care of the time factor. Estimate the detention time Dispersion: The ‘‘spread’’ of a substance during a flow due to
in the plate settlers. currents, turbulence, or molecular diffusion.