1.01
DESCRIPTION
A.
SCOPE
This section provides
specifications for one field erected trickling filter
odor control unit to treat off gases from the head works
area to oxidize hydrogen sulfide and other organic
compounds. The trickling filter odor control system shall
consist of a bolted glass fused to steel tank lined with
a PVC liner, fitted with a fiberglass media support
system, graded lava rock media, a spray header system
with recirculation pump, fiberglass centrifugal fan, fan
damper, pH control loop and a make up water
system.
B.
TYPE
The unit shall be of
the trickling filter type where a bacterial mass is
supported on the lava rock media. Water is circulated
over the media bed and the bacteria oxidize the hydrogen
sulfide and other organic compounds. Favourable bacteria
are selected by maintaining a pH of approximately 2.5 in
the circulating water. Make up water is used to control
the pH.
C. PERFORMANCE
REQUIREMENTS
1. GENERAL - Equipment
furnished under this section shall be suitable for
treating odorous gases air with hydrogen sulfide and
other organic odors commonly emanating from domestic
sewage. The temperature of the air shall be in the range
of 40 to 110 degrees Fahrenheit and shall be saturated
with moisture, water temperature shall be in the range of
50 to 90 degrees Fahrenheit. The equipment will oxidize
the hydrogen sulfide and produce sulphuric acid in the
process causing the water flowing over the media to have
a low pH with normal conditions in the range of 2 to 3
pH. Excursions to pH values of 1 are possible. The water
recirculated will be secondary effluent from the plant
activated sludge plant.
2. FUNCTIONAL - The
unit shall treat the air and reduce the hydrogen sulfide
to less than 1 ppm before it is passed to a second stage
of activated carbon treatment. The unit shall be
automatic in that the pH of the circulating water shall
be maintained at approximately 2.5 by a pH sensor and
control loop that controls the introduction of make up
water that has a pH of approximately 7.5. A dampener
shall be provided upstream of the unit for manual control
of the rate of air flow.
D. OPERATION
CONDITIONS
The air fed to the
system shall contain hydrogen sulfide in the range of 5
to 50 ppm by volume and other organic compounds. The flow
rate of air will be ________ scfm.
E. DESIGN
REQUIREMENTS
The system shall be
designed for continuos duty under the conditions
specified in paragraph 1.01. D
1. TANK - The tank
shall be designed assuming that it is filled with water
and the lava rock media. The tank shall also be designed
for seismic zone 4 requirements.
2. CORROSION
RESISTANCE - All material in contact with the
recirculating water and moisture laden treated air shall
be designed for use in an environment with a pH of 1.0.
No metal parts shall be exposed to this
water.
3. MAINTENANCE ACCESS
- The tank shall be provided with a manhole for access to
the area of the media bed to inspect the spray nozzle
system. A manhole shall also be provided for access to
the plenum under the media. The manhole shall also be
designed for loading the lava rock media into the
unit.
1.02 QUALITY
ASSURANCE
A. REFERENCES
This section contains
references to the following documents. They are part if
this section as specified and modified. In case of a
conflict between the requirements of this section and
those of the listed documents, the requirements of this
section shall prevail.
References /
Title
ANSI/AWWA D103 /
Factory-Coated Bolted Steel Tanks for Water
Storage
ASTM A570 GRADE 30 /
Steel Specification
SAE GRADE 3 / Bolt
Standard
ASTM A490 / Bolt
material
NEMA ICS 2-88 /
Industrial Control Devices, Controllers and
Assemblies
1.03
SUBMITTALS
The following material
shall be provided in accordance with Section
_______
A. Tank layout in
plan, cross section and elevation showing all
penetrations including location of fan, recirculation
pump, make up water connection, pH sensor location,
treated air outlet and manholes.
B. A copy of the
specification section with all addenda updates and all
referenced sections with all addenda updates, with each
paragraph check marked to show specification compliance
or marked to show deviations.
C. Instrumentation
diagrams for the pH control loop.
D. Local control panel
layout including door and rear panel equipment and
dimensions
E. Catalog data on all
components and accessories as specified in Section
______
F. Motor data on all
ancillary electrical components.
G. Certification of
unit responsibility for the complete
system
H. List of
materials
I. Shop drawings
including locations of all piping, electrical,
instrumentation and structural details.
J. A copy of all
related contract schematics, structural and mechanical
drawings with all piping, foundation supports, and layout
sizes and dimensions requiring Contractor confirmation
marked.
K. Complete structural
design including anchorage for all tanks and
components.
2.01
ACCEPTABLE PRODUCTS
The odor control
system shall be Polytech Systems, Incorporated,
Littlerock, California, (661) 944-0855 or Agency approved
equal modified as necessary to provide the specified
features and to meet the operation
requirements.
2.02
MATERIALS
A. Materials for
components shall be as follows:
Tank - Bolted mild
tank with thermoset epoxy coating on the inside and
outside.
Tank Lining -
Plasticized PVC
Media support -
Fiberglass
Media - Lava Rock
Fan -
Fiberglass
Pump -
Fiberglass
Piping -
PVC
Nozzles -
Polypropylene
B. Local control panel
enclosures shall be fiberglass NEMA 4X
construction
2.03
FABRICATION AND MANUFACTURE
The system shall
include a complete bolted steel tank, media, media
support, tank lining, fan, pH control system,
recirculation water system, make up water system and
spray nozzle system. All of the system shall be designed
under the supervision of one manufacturer.
2.04
COMPONENTS
A.
GENERAL
Provide one trickling
filter type odor control system.
B. TANK
One ___foot nominal
diameter by ___ foot tall bolted steel tank thermoset
epoxy coated designed under the ANSI/AWWA standard AWWA
D503. The tank shall be embedded in the concrete floor
slab and shall have a conical roof. A manhole that is at
least 24 inches in one direction and 15 inches in the
other direction shall be mounted near the outside tank
ladder. A 24 inch by 24 inch access door shall be
provided near the bottom of the tank. An aluminium ladder
shall be provided for access to the roof of the unit. A
safety cage on the ladder shall be provided with a step
off platform. The tank shall be hydrostatically tested
before it is lined and the media installed.
C. MEDIA SUPPORT
SYSTEM
The lava rock media
shall be supported on a wood encapsulated with fiberglass
beam and column system with fiberglass grating and
polypropylene mesh. The system shall be free-standing and
not attach either to the concrete or the steel tank.
Lateral forces may be resisted by the tank walls
providing no penetrations of the liner are used. All
fiberglass shall be joined by bonding or through the use
of non-metallic bolts.
D.
MEDIA
The tank shall have a
depth of 10.5 feet of lava rock media which has been
screened such that all media passes though a 1 _ inch
screen and is retained on a 3/4 inch
screen.
E.
LINING
The tank shall be
completely lined with a 1/8 inch plasticized liner that
is mechanically attached to the tank with encapsulated
batten strips and encapsulated polypropylene support
pipes held up with stainless steel aircraft cable. Where
necessary the lining shall be protected with
polypropylene padding to prevent damage from the
fiberglass support media support
structure.
F.
PIPING
The piping for the
system shall be rigid PVC schedule 80 and shall include
the suction piping for the water recirculation line the
pump discharge piping and the spray header piping.
Nozzles shall be provided on staggered 3 foot centers to
completely wet the media at all times. Nozzles shall be
of PVC or Polypropylene as manufactured by Bete and shall
be of the non-clogging design.
G. RECIRCULATION
PUMPS
One recirculation pump
and one standby recirculation of the Goulds fiberglass
type shall be provided.
H. CENTRIFUGAL
FAN
One centrifugal fan of
fiberglass construction shall be provided. It shall have
a stainless steel shaft and a rectangular opening _____
inches square with a round flanged fiberglass duct
transition on the suction side with a fiberglass damper
between flanges on the suction duct. The fan shall
compress air at _______ scfm to produce a pressure of 3
inches of water column. The fan shall be provided with a
____ hp minimum motor of TEFC
construction.
I. UNIT CONTROL
PANEL
One unit control panel
shall be provided to house a pH meter and a control
system that activates a make up water valve to admit
water to increase the pH as necessary to maintain an
operator adjusted set point. A corresponding overflow
shall be provided to allow excess water to be returned to
the treatment plant.
J. ANCHOR
BOLTS
Anchor bolts for the
recirculation pumps, the fan and the control panel shall
be 316 stainless steel.
K. LEAK DETECTOR
(Optional)
Install a leak
detector at the lowest point of the tank between the
liner and the tank.
3.01
GENERAL
Install in conformance
with the manufacturers instructions all equipment and
materials. The contractor shall provide all materials and
accessories to ensure a complete working system, whether
or not shown on the project drawings. The tank shall be
erected by the tank manufacturer trained and certified
subcontractor.
3.02 PROTECTIVE
COATINGS
A 9 volt holiday test
shall be performed on the completed tank and all areas
which show electrical leakage shall be repaired in
accordance with the tank manufacturers
instructions.
3.03
LINING
The lining system
shall be tested by pressurising the space between the
tank wall and the lining with low pressure air and
testing the liner with a soap solution to locate any
penetrations. Penetrations shall be repaired with heat
welded patches and the tank retested.
3.03 FIELD TESTING
AND START UP
The manufacturer of
the pumps, the fans and the pH control system shall
inspect the installed units and train the operating staff
in the maintenance and operation of these elements. The
system manufacturer shall provide start up assistance and
training to bring the unit on line. The manufacturer
shall help in providing proper bacterial seeding of the
media to get the process initiated. After the biomass has
stabilised, the manufacturer shall make another trip to
inspect the unit and conduct any final training. The
manufacturer shall be available by telephone to assist
the operation staff with any technical questions during
the period where the initial biological culture is being
developed.
