United States                June
                                                             Environmental Protection        1983
                                                             Agency
 • Sedalia, MO - 2.6 MGD
 • Gallatin, MO - 0.225 MGD

These proposed innovative facility plans also in-
clude modifications such as a shorter hydraulic de-
tention time, peak flow clarifiers, propellor-type mix-
ers, and fine bubble aeration.that contribute in part
to the projected cost savings for the four facilities
shown in Figure 4.

Actual bid costs for the 40 MGD Little Blue Valley
project (Jan. 1983 $) were projected to be
$23,808,000 for the total treatment plant. Bid costs
relative to the Intrachannel Clarifier portion of the
project were $6,158,700 for two 10 MGD aeration-
clarification basins. This represents a cost of slightly
less than $.31 per gallon of treatment capacity.
v>EPA   An  Emerging
              Technology

              Intrachannel
              Clarification

              A  Project
              Assessment
       For additional information contact:
EPA-OWPO(WH-547)
401 M Street, SW
Washington, DC 20460
(202)362-7370/7369

EPA Region 1
John F. Kennedy Federal Building
Boston, MA 02203

EPA Region 2
26 Federal Plaza
New York, NY 10278

EPA Region 3
6th & Walnut Streets
Philadelphia, PA 19106

EPA Region 4
345 Courtland Street, NE
Atlanta, GA 30308

EPA Region 5
230 South Dearborne Street
Chicago, IL 60604
                         EPA-MERL (489)
                         26 West St. Clair Street
                         Cincinnati, OH 45268
                         (513)684-7614

                         EPA Region 6
                         1201 Elm Street
                         Dallas, TX 75270

                         EPA Region 7
                         324 East 11th Street
                         Kansas City, MO 64106

                         EPA Region 8
                         1860 Lincoln Street
                         Denver, CO 80203

                         EPA Region 9
                         215 Fremont Street
                         San Francisco, CA 94105

                         EPA Region 10
                         1200 6th Avenue
                         Seattle, WA 98101
                                    <

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Intrachannel Clarification - A Project Assessment of a Pi
Introduction
Community leaders are becoming more and
more cost conscious when selecting wastewater
treatment alternatives. Initial capital investments
will continue to be important, but operation and
maintenance costs will become a greater
consideration in process selection. This cost
awareness is leading consulting engineering
professionals to seek more innovative solutions
to meet their clients' needs. One example of this
approach is an Intrachannel Clarifier system
developed by Bums & McDonnell of Kansas
City, Missouri, in cooperation with the staff of the
Little Blue Valley Sewer District, Kansas City,
Missouri,  Metropolitan Area. This cost-saving
approach to modify the oxidation ditch process
has become an integral part of the District's
planned 40 MGD treatment facility, which will
serve a 238 square mile watershed area.
Longitudinal Section
                                                    Figure 2 Clarifier Longitudinal Cross-Section
        Mechanical
        Skimming
                Hydraulic
                Skimming,
  Note: TiifNne aerator was later replaced with
      propeltor mixer and fine bubble aerator.
                    Waste
                    Sludge
                                                                      ^ Plant
                                                                      ^Effluent
 Figure 1  Process Plan View for the original 1.0 MGD Little Blue Valley Pilot Plant

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pmising  Process  Modification
     Sludge Age

     Overflow Rate



      Mixed Liquor
        Concentration

     Aeration

      Effluent Quality
10 Days

600-800 gallon
  per day per
  sq. ft.

3,000-3,500 mg/l
10 hr.
     mg/l BOD5
* 20 mg/l SS
    Table 1  Typical Pilot Plant Operating Conditions
    This process modification was tested and demons-
    trated as part of a Step II construction grant from
    the U.S. EPA and was selected as one of the Ten
    Outstanding Achievements in the National Society
    of  Professional Engineers' 16th Annual Competition.

    This fact sheet brings this emerging technology to the
    attention of potential users. Although the fact sheet
    describes the Bums & McDonnell Intrachannel
    Clarifier design, there  are currently two other designs
    for this process which have been developed by
    EIMCO and Beard Engineering, Inc.

    The Process
    The Intrachannel Clarifier is a modification of the
    oxidation ditch process which combines the aeration
    and clarification processes in one basin. The screened
    wastewater enters the basin, is aerated, and then
    passes under the Intrachannel Clarifier where a
    mixture of the wastewater and activated sludge
    (mixed liquor) rises through the clarifier bottom panels.
    As the mixed liquor flows up into the clarifier, solids
    settle, fall through the bottom openings and return to
    the continuously flowing  mixture. Effluent is removed
    from the quiescent zone in the, upper portion of the
    Intrachannel Clarifier via the submerged  orifice effluent
    pipe. Figure 1 to  the left shows a plan view of the
    original pilot process. Figure 2 shows a cross-
    section of the clarifier.
Field Testing
The Intrachannel Clarification concept was tested
as a wastewater treatment solution that would re-
duce capital and O&M costs for the Little Blue Val-
ley Sewer District's planned 40 MGD facility. This
concept has been demonstrated via pilot-scale at
the site of the District's 20 MGD Interim Treatment
Plant. The pilot plant is an oval basin -110 feet
long by 32 feet wide - with a liquid depth  of six feet.
The pilot plant was designed to treat 1  MGD of
screened wastewater and has operated at flow
rates from 0.3 MGD up to 1.3  MGD. Table  1 shows
typical operating conditions for the pilot plant. A
novel aeration system consisting of a slow rpm
propellor-type mixer and fine bubble aeration was
tested and is proposed for the full-scale 40  MGD
system. Figure. 3 below shows the process  schematic
for the planned 40 MGD facility.

Projected Advantages
Pilot results indicate the Intrachannel. Clarifier eli-
minates many of the problems associated with con-
ventional secondary clarifiers. There are no sludge
blankets or compression zones, and the full depth
of the clarifier is available for maximum settling. As
the solids settle in the clarifier, they also act as a
nucleus to attract and remove  material in  the liquor
                                Influent  ,
                                	.—>Jpumps'

. '•>
Fir
Ae



e Bubble
ation













Propeller


                                                    Marific.jtion
                                Effluent
                                r<	
                                      X;   ••••:•*$
                                                             Figure 3  Schematic of Planned Full-Scale System

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flowing upward into the quiescent zone. The under-
flow beneath the clarifier pulls the settling solids
back into the mixed liquor stream without the use of
a return sludge pump. Thus, no control over sludge
return is necessary and sludge age is easily controlled
by wasting mixed liquor.

Many pieces of equipment associated with conven-
tional activated sludge processes are not needed
with this system. The system also has a major
advantage over the conventional oxidation ditch be-
cause the hydraulic detention time is lower (10 hrs.
vs.  24 hrs.), resulting in a smaller basin volume and
associated cost savings.

Cost Comparisons
Projected capital and first year operation and
maintenance (O&M) costs for proposed facilities
which incorporate Intrachannel Clarification and for
conventional oxidation ditch technology are shown
in Figure 4.  These curves are based on estimated
costs (1982 $) for the following four proposed muni-
cipal wastewater treatment plants:

  • Little Blue  Valley Sewer District
    (Jackson  County, MO) - 40  MGD
  • Storm Lake, IA - 3.34 MGD
                 Total Annual O&M Costs
                     Flow (MGD)
Figure 4 Cost Curves
 Original 1 MGD Pilot System at Little Blue Valley Sewer-District

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