| (ii) An impermeable concrete pad must be installed
over a liner in locations where the groundwater table is within 4.0
feet of the bottom of the liner.
(3) Innovative or Non-Conforming Sludge Drying Beds.
The executive director will review any vacuum assisted sludge drying
beds or other variations to the gravity drying bed concept as innovative
and non-conforming technologies subject to §217.7(b)(2) of this
title (relating to Types of Plans and Specifications Approvals).
(4) Rotary Vacuum Filtration.
(A) Filtration Rate. The engineering report must justify
the value calculated for the rates of filtering for various types
of sludge with proper conditioning, using Table J.4. in Figure: 30
TAC §217.250(e)(4)(A).
Attached Graphic
(B) Duplicate Equipment. Unless two treatment trains
are provided, a feed pump, a vacuum pump, and a filtrate pump must
be provided in duplicate to allow equipment alternation. Spare filter
fabric must be kept at the wastewater treatment facility, except when
metal coil filters are used.
(C) Filter Equipment. Parts that will get wet must
be constructed of corrosion-resistant material. Drum and agitator
assemblies must be equipped with variable-speed drives, and provisions
must be made for adjusting the liquid level in the filtration system.
(D) Pumps.
(i) A vacuum pump with a capacity of at least 1.5 cubic
feet per minute per square foot must be provided for metal-covered
drums.
(ii) A dry-type vacuum pump must have a vacuum receiver.
(iii) A filtrate pump must have adequate capacity to
pump the maximum amount of liquid to be removed from the sludge.
(iv) Each filter must be fed by a separate feed pump
to ensure a proper feed rate.
(5) Centrifugal Dewatering.
(A) The engineering report must justify the sizing
and design of a centrifugation system. A centrifuge design must be
based on performance data from a similar centrifuge when available.
If no performance data is available, the results of a pilot or full-scale
test must be used.
(B) Selection of a material for a scroll must include
consideration of the amount of grit expected in the sludge.
(C) A centrifugation system must include adequate sludge
storage, based on the disposal process.
(D) Unless two treatment trains are provided, a centrifugation
system must have the following spare equipment, including necessary
connecting pipes and electrical controls:
(i) drive motor;
(ii) gear assembly; and
(iii) feed pump.
(E) A feed pump must have a variable speed drive.
(F) Each centrifuge must have a separate feed system.
(G) A centrifuge must be equipped for variable scroll
speed and pool depth.
(H) A centirugation system must have a crane or monorail
for equipment removal and maintenance.
(I) A centrifuge system must provide access for wash
down of the interior of each centrifuge.
(6) Plate and Frame Presses.
(A) Sizing.
(i) The design of a plate and frame press must be based
on performance data developed from a plate and frame press of similar
size with similar operational characteristics. If no performance data
is available, the results of pilot scale tests or full-scale tests
must be used.
(ii) The design of a plate and frame press may be based
on appropriate scale-up factors for full size designs if pilot scale
testing is done in lieu of full-scale testing.
(iii) The engineering report must justify the size
of a plate and frame press.
(B) Duplicate Equipment and Spare Parts. Unless multiple
units are provided, a plate and frame press system must include the
following spare equipment:
(i) one duplicate feed pump;
(ii) two extra plates, or at least one extra plate
for every ten plates required for startup, whichever is greater;
(iii) one complete filter fabric set;
(iv) one closure drive system;
(v) one air compressor; and
(vi) one washwater booster pump.
(C) Operational Requirements.
(i) The filter feed pumps must be able to handle initial
high volume flow, low pressure filling, and sustained periods of operating
at 100 pounds per square inch to 225 pounds per square inch.
(ii) A plate and frame press system may include an
integral pressure vessel to produce initial high volume flow.
(iii) A plate and frame press system may use operating
pressures less than 225 pounds per square inch if the engineering
report justifies the design operating pressure using actual performance
data from a plate and frame press that processes similar sludge.
(iv) A plate and frame press system may include provisions
for sludge-cake breaking to protect or enhance down line processes.
(D) Maintenance.
(i) A plate and frame press system must have a crane
or monorail capable of removing the plates.
(ii) A plate and frame press system must have a high-pressure
water or acid wash system to clean the filter.
(7) Belt Presses.
(A) Sizing.
(i) Actual performance data developed from a wastewater
treatment facility with similar operational characteristics must be
used to size a belt press system. If pilot plant testing is performed
in lieu of full-scale testing, appropriate scale-up factors must be
used to develop a full-scale design.
(ii) A belt press system must have a duplicate belt
press, or another method of sludge processing or disposal that has
been approved in writing by the executive director, if the design
flow exceeds 4.0 million gallons per day.
(iii) The engineering report must include all data
used to size a belt press system.
(B) Duplicate Equipment and Spare Parts. Unless multiple
belt press units are provided, a belt press system must have the following
spare equipment:
(i) one duplicate feed pump;
(ii) one washwater booster pump;
(iii) one complete set of belts;
(iv) one set of bearings for each type of press bearing;
(v) one set of tensioning equipment;
(vi) one set of tracking sensors;
(vii) one set of wash nozzles;
(viii) one doctor blade; and
(ix) conditioning or flocculation drive equipment.
(C) Conditioning. The engineering report must include
the polymer selection methodology, account for sludge variability,
and document the anticipated sludge loading to the belt press.
(D) Sludge Feed.
(i) The sludge must be fed at a relatively constant
rate that does not interfere with polymer addition and belt press
operation.
(ii) The engineering report must include the range
in feed rate variability.
(iii) A belt press system may include grinders ahead
of a flocculation system.
(iv) The sludge feed must provide a method for uniform
sludge dispersion on a belt.
(v) A belt press system must use thickening of the
feed sludge, unless the engineering report justifies separate thickening
or dual purpose thickening.
(E) Filter Press Belts.
(i) A belt must have a variable speed drive.
(ii) A belt press system must have belt tracking and
tensioning equipment.
(iii) The engineering report must justify the weave,
material, width, and thickness of the belts.
(F) Filter Press Rollers.
(i) The rollers must have a protective finish.
(ii) The maximum roller deflection and operating tension
of the belt must be included in the engineering report to justify
equipment selection.
(iii) The roller bearings must be watertight and rated
for a life of 100,000 hours.
(G) Spray Wash System.
(i) A belt press system must use high-pressure wash
water for each belt.
(ii) The design of a spray wash system must specify
the operating pressure at the point of washwater discharge.
(iii) A spray wash system must allow cleaning without
interfering with the spray wash system operation.
(iv) The engineering report must justify the nozzle
and nozzle cleaning system selection.
(v) A belt press system must have replaceable spray
nozzles and spray curtains.
(H) Maintenance Requirements.
(i) A belt press system must have drip trays under
the belt press and under the thickener when gravity belt thickening
is employed.
(ii) The side and floor of a belt press must have adequate
clearance for maintenance and removal of the dewatered sludge.
(iii) An electrical panel or other component subject
to corrosion must be protected from splashes and corrosive gases,
or be located outside of the belt press area.
(iv) A doctor blade clearance must be adjustable.
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