Akron Water Pollution Control Station No Feasible Alternative

Alternative 3A will include four (4) new, 42.5 MGD high-rate treatment processes to
provide clarification/filtration of final settling tank overflow plus the necessary hydraulic
improvements up to 170 MGD. Refer to Figure 4-4.
Alternative 3B will include five (5) new, 42.0 MGD high-rate treatment processes to
provide clarification/filtration of final settling tank overflow plus the necessary hydraulic
improvements up to 210 MGD. Refer to Figure 4-5.
Alternative 4 – Membrane Filtration
This alternative considers the application of wastewater membrane technology to filter the
mixed liquor effluent from the aeration basins to provide the necessary additional clarification
capacity. The membrane filters would work in concert with the existing final settling tanks.
Based on a review of this concept with two leading manufacturers, it is proposed to locate the
membranes in separate, new tanks north of Aeration Basin No. 6. The required pumping and
piping systems would be similar to Alternative 2. Use of membranes will require fine screening
of primary effluent and primary effluent pumping. A two or three millimeter screen size is
recommended. Because of the additional hydraulic head required for this alternative, it will be
necessary to significantly modify the secondary influent flow splitting chamber (Aeration Influent
Flume). The aeration basin walls will be raised. Two capacity increase increments were
evaluated.
Alternative 4A will include two membrane filtration tanks to provide 40 MGD additional
solids separation capacity plus the necessary hydraulic improvements and a new Fine
Screening and Pumping Facility, for a total secondary treatment capacity of 160 MGD. Refer to
Figure 4-6.
Alternative 4B will include four membrane filtration tanks to provide 80 MGD additional
solids separation capacity plus the necessary hydraulic improvements and a new Fine
Screening and Pumping Facility, for a total secondary treatment capacity of 200 MGD. Refer to
Figure 4-7
Group 5 Alternatives – Membrane Bioreactor (MBR) Facility
The aeration basins would be converted to membrane bioreactor tanks in this alternative.
Because MBRs function with a much higher mixed liquor suspended solids concentration
(approximately 10,000 mg/l), not all of the six aeration basins will be needed. A new fine
screening (two to three millimeter) facility would be located upstream of the MBR tanks following
primary treatment (primary settling tanks will remain in service in order to maintain the current
sludge process train). To accommodate the headloss imposed by the fine screens, and provide
a deeper tank depth as required for the MBR equipment, it is proposed to pump primary effluent
to the new fine screening and MBR facility. Because the Cuyahoga River 25-year flood
elevation impacts WPCS effluent hydraulics, a primary effluent pumping station will also be
required. Permeate pumps will draw mixed liquor through the membranes and discharge the
filtrate to the secondary effluent conduits. Piping galleries will be required between
compartmentalized sections of the modified aeration basins to provide space and access to
influent and effluent piping and to access the permeate pumps. Two capacity increase
increments were evaluated.
Alternative 5A will include the conversion of three (3) aeration basins into MBR tanks
with an average day capacity of 90 MGD and a maximum day capacity of 170 MGD. A primary
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