Figure 2: Odor Control System in Service
Odors at Singapore’s Ulu
Pandan Sewage Treatment
Ulu Pandan Sewage Treatment Works (STW)
Ammonia, Hydrogen sulfide, Sodium hydroxide, Sodium
SUMP-GARD Thermoplastic Vertical Pump
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Reprinted from Water Engineering & Management
Water & Waste Digest
By Larry Lewis and Ken Galardi, P.E.
Three significant reputations for innovative, reliable solutions to
environmental problems came together as the Singapore Ministry of the
Environment (ENV) planned for expansion and upgrading of its water
and wastewater treatment facilities at Ulu Pandan Sewage Treatment
First and foremost was the ENV's Mission Statement that Singaporeans
were to have "a clean living environment and enjoy a high standard of
environmental public health to protect against the spread of
communicable disease." This was to be accomplished through the use
of first-rate infrastructure for waste disposal, implementation of
pollution control measures and maintenance of high public health
As part of their overall environmental program, ENV turned to the
consortium of Mitsubishi International, IHI Industries and Jurong
Engineering Limited to upgrade the odor control systems at the Ulu
Pandan STW. The consortium selected Camp Dresser & McKee, Inc., as
the overall project designer and USFilter/RJ Environmental Products,
San Diego, Calif., as the odor control system supplier.
USFilter selected Vanton Pump & Equipment Corp., Hillside, N.J., a
manufacturer of thermoplastic fluid handling equipment, to provide the
specialized nonmetallic pumps required to handle the aggressive fluids
needed to neutralize the noxious emissions.
Hydrogen sulfide, ammonia or other organic compounds typically cause
the generation of odors from municipal processing operations.
Treatment of these odors at Ulu Pandan STW was accomplished
through a large centralized odor control facility incorporating 17 process
"trains," each consisting of several packed tower scrubbers in series,
followed by a dual bed activated carbon absorber. Each scrubber was
equipped with duty and standby liquid recirculation pumps sized to
maintain the proper degree of liquid-to-gas contact in the scrubber. A
total of 76 recirculation pumps was used. Thermoplastic pumps and
fluid handling piping were selected because of their chemical resistance
to the acid, caustic and bleach used in the scrubber systems, and their
proven reliability in similar applications.
Figure 1 illustrates a typical odor control system installed in the Ulu
Pandan STW. These systems were field-assembled and tested to
assure the required pH control, reduction of emissions and other
performance guarantees. A critical aspect of these systems is their
ability to handle the corrosive chemicals required for the neutralization
process and the dependable recirculation of these neutralizing
chemicals, particularly sodium hypochlorite (NaOCI) and sodium
hydroxide (NaOH). Figure 2 is a close-up of one of these systems in
operation, and Figure 3 shows a group of five such systems in the Odor
Treatment Building of the STW facility.
To provide for the dependable continuous circulation of these
neutralizing chemicals, heavy-duty vertical centrifugal pumps with all
fluid contact components made of solid, homogeneous polypropylene
were specified. This thermoplastic material is inert to the chemicals and
the pumps are rated for flows to 250 gpm (95 L/m) against a 45 foot (14
m) head over a broad temperature range. Seventy-six of these pumps
were required for the 38 packaged odor control systems at this site.
Figure 4 shows a group of these pumps ready for shipment after being
tested for performance against the specific conditions of service.
In explaining the reason for the specific pump design, engineers
emphasized the following significant specifications.
• The design should limit fluid contact to nonmetallic materials.
• The stainless steel shaft should be completely encased in
polypropylene so that no metal would contact the fluid.
• The cover plate over the fluid tank area should be supplied in the same
material as the pump.
• The immersed bearings should be nonmetallic and consist of ceramic
bearings running against Vanite outer bearings.
• The impeller should be solid polypropylene molded around a stainless
steel dynamically balanced insert, keyed to press fit into the shaft for
• The pump casings were to be designed for centerline discharge and
configured to accommodate larger sized impellers in order to provide
increased flows at lower power input. They were to be solid,
thermoplastic molded components, not metal components with applied
A schematic view of the pump design is show in Figure 5.
The Ulu Pandan STW Odor Treatment Building has been fully on line
since July 2000, providing efficient and reliable odor control to protect
plant personnel, neighbors and the environment.
Figure 3. This compact packed tower
scrubbing system relies on two very
different thermoplastic pumps: a
flexible liner peristaltic type rotary
pump to meter 50% NaOH on demand to the
vertical in-tank circulating pump, which
provides a continuous flow of 5% NaOH
scrubbing fluid to the tower.
Figure 3: Odor Control Systems at the
Odor Treatment Building
Figure 4: Centrifugal Pumps Ready for
In the 1950, Vanton developed a revolutionary all-plastic pump for use in conjunction with the first heart-lung device. The design limited fluid contact to only two non-metallic parts: a plastic body block and a flexible liner. This was the birth of our Flex-I-Liner rotary pump. Its self-priming sealless design made it an industry standard for the handling of corrosive, abrasive and viscous fluids as well as those that must be transferred without contaminating the product. Vanton now offers the most comprehensive line of thermoplastic pumps in the industry.
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Vanton Pumps (Europe) Ltd.
Unit 4, Royle Park
Congleton CW12 1JJ