WASTEWATER SLUDGE TREATMENT CASE STUDY Metropolitan Sewer District (MSD) Cincinnati, Ohio

WASTEWATER SLUDGE TREATMENT
CASE STUDY
Metropolitan Sewer District (MSD)
Cincinnati, Ohio
Situation
The Metropolitan Sewer District
(MSD) of Greater Cincinnati, Ohio is
a 90 mgd primary treatment, 55 mgd
activated sludge treatment plant.
Solids processing includes gravity
thickening of primary sludge, dissolved air flotation, thickening of secondary sludge, holding tank storage,
belt filter press dewatering and
pumping of cake to the old outdated
multiple hearth incinerator.
Solution
After an exhaustive feasibility study,
MSD and the consultant, Black &
Veatch, selected the ODI Hot
Windbox HTFB ( high temperature
fluid bed) to replace its existing aging
© ONDEO Degremont, Inc. - October 2001
multiple hearth. The ODI incinerator
was determined to be the most economic and environmental solution.
The system was commissioned in
June 2000. It is readily adapted to
non-continuous operation and is easy
to operate and maintain.
The unit has met performance targets
since its first few days of operation.
Air emission rates are substantially
lower than permit requirements, and
there is no visible plume.
System Description
The unit is the largest municipal Hot
Windbox HTFB built in the USA to
date, with a design capacity of 72 dry
ton per day. It is a 24 ft ID freeboard,
equipped with a refractory arch distributor to minimize auxiliary fuel consumption. The system includes a
heat recovery system with two heat
exchangers, a quench pre-cooler and
a venturi scrubber, which is followed
by a cooling tray tower.
Contract Type
ONDEO Degremont, Inc. was contracted for the supply of the HTFB
system, start-up, operator training
and commissioning.
Process Flow Diagram
Compressed Air
Continuous Emissions
Monitoring System
Exhaust Gas
Duct
High Pressure
Water Pump
Sand
Storage
Service Water
Stack
Sand
Heat Exchangers
Sludge
Feed
Primary
Secondary
Quench
Sludge
Dewatering
Sludge Feed Pump
Tray
Scrubber
Purge Air Blower
Fluidizing Air
Blower
Auxiliary
Fuel
Oil
Preheat
Gas
Feed
Preheat Burner
Combustion Air
Venturi
Scrubber
Ash Treatment
Preheat
Auxiliary
Cincinnati Metropolitan Sewer District
System Air Emission Performance
Air Pollutant
PM, Lb/dry ton
THC, ppmv as propane
CO, ppmv as propane
NOx, lb/dry ton
SO2, lb/dry ton
Opacity %
Emission
Testing
0.04
0.50
2.28
0.47
0.07
0
Permit
Limit
1.30
100
N/A
5.00
7.40
20
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