Hoffland
Environmental’s low profile gravity flow sand filter continuously
filters, by gravity, liquid suspensions producing excellent filtrate
while simultaneously and continuously cleaning the filtration bed.  |
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Hoffland
Environmental’s low profile gravity flow sand filter continuously
filters, by gravity, liquid suspensions producing excellent filtrate
while simultaneously and continuously cleaning the filtration bed. HEI’s low profile filter backwashing is a unique
process. A slip stream of the most contaminated media, is taken from
the bottom, cleaned and automatically redeposited on the top of the
filter bed. The filter bed media slowly moves downward as the filtered
water moves upward through the bed.
Since the HEI gravity flow sand filter
continuously cleans a small portion of the media bed, the dirty
backwash water, comprising approximately 5% of the total flow, may be
continuously returned to the primary clarification device without
stopping or surging the system.
A conventional pressure sand filter backflushes on
a batch basis producing large intermittent flows of wastewater. In
addition, the large volume of backflush water must be accumulated and
held in reserve until it can slowly be treated. The HEI low profile
continuous backflush sand filter eliminates the requirement of tanks
and pumps to store, pump and process the backflush water.
HEI gravity flow sand filter is a low profile
designed unit enabling direct flow of the influent from standard
clarifiers. A conventional clarifier does not need to be raised to
provide the required water column for HEI’s sand filter operation. And,
as well, pumping or lift station from standard clarifiers are not
required with HEI’s low profile media filter. |
Advantages of HEI’s Low Profile Media Filter |
Low Profile Gravity Sand Filter VS. Pressure Sand Filter
 Filtration Equipment Required: 1. One (1) HEI Gravity Sand Filter |
Filtration Equipment Required:
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Influent Surge Tank
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Influent Pressurization Pump
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High Pressure Vessel
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Pressure Sand Filter
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Backflush Pump
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Backflush Reservoir
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Waste Backflush Surge Reservoir
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Waste Backflush Return Pump
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Pressure Sand Filter Controls
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Pressure Switch
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Pressure Guage
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Air Vent
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Compressed Air Media Scrubber
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Pressure Relief Valve
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Automatic Valves With Operators
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Valve Positioners
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Valve Position Indicators
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Central Control System
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Motor Starters
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Disconnect
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PLC
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Switches
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Continuous
Continuous filtration with only a small continuous flow of
backflush wastewater creates problem free performance. HEI’s trouble
free units provide the following advantages:
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Eliminates equipment and tankage to store large volume of backwash water.
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With a small slip stream of backflush water, the wastewater treatment system does not need to be increased in size to accommodate large intermittent flows backflush water.
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Eliminates the pumps required for backflush.
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Eliminates electronic controls, PLC’s, motor starters, pressure switches, level controls required to control the filter and and process the backflush waste water.
Uncomplicated Design |
Full automatic operation is achieved without
operator assistance. The filter media is continuously backwashed at a
rate controlled by simply adjusting the air supply to the air lift
mechanism. This eliminates the batch operation common to pressure media
filters backwashing. Since there are no moving parts or pumps required
in the HEI gravity sand filter, the required operator attention is
minimal.
Low Profile Design
The
maximum height of the HEI gravity sand filter is only nine (9) feet,
gravity flow from a conventional clarifier is readily achieved.
Elevating the clarifier, recessing the sand filter or additional pump
stations are not required.Performance
The HEI gravity flow sand filter continuously
cleans a slip stream of the contaminated media and redeposits the clean
media on the filter bed. The filtrate continuously flows through clean
media.
Efficient Design
With the internal media backwashing design,
capital cost of all external backwashing equipment including backwash
influent storage tank, backwash effluent storage tank, high volume
backwash pumps, and all related controls, is not required. The floor
space required is limited to only the HEI low profile sand filter
vessel. The overall cost of HEI’s self cleaning gravity flow media
filter is significantly less than a pressure sand filter system, when
all tanks pumps, controls etc. are considered.
Simple Installation
HEI’s gravity flow media filter is shipped
completely pre-assembled. Only influent, effluent piping, and air
supply are required.
Complete Range of Sizes
The HEI sand filter is manufactured in standard
sizes varying from 10 sq. ft. (50 gpm) to 150 (750 gpm) sq. ft. of
surface area in one unitized package. Multiple units may be manifolded
together for larger flow rates.
HEI Low Profile Gravity Sand Filter |
"The Proven Concept in Sand Filtration"
The
HEI Sand Filter is a continuous backwash, upflow, deep-bed granular
media filter. The filter media is continuously cleaned by recycling the
sand internally through an airlift pipe and sand washer. The
regenerated sand is redistributed on top of the sand bed, allowing for
a continuous uninterrupted flow of filtrate and reject (backwash)
water. Feed is introduced into the bottom of the filter,
then flows upward through the inlet tube (H) and is evenly distributed
into the sand bed through the open bottom of an inlet distribution hood
(A). The influent flows upward, through the downward moving sand bed
(B), with the solids being removed. The clean filtrate exits from the
sand bed, overflows a weir (C), and is discharged from the filter (D).
Simultaneously, the sand bed, along with the accumulated solids, is
drawn downward into the suction of an airlift pipe which is positioned
in the center of the filter. A small volume of compressed air is
introduced into the bottom of the airlift (E). The air lifts the dirty
sand up the airlift pipe, and air scours the sand at a rate of 100 to
150 SCFM/ft.2. The impurities are scoured loose from the sand during
this violently turbulent upward flow. Upon reaching the top of the
airlift (F), the dirty slurry spills over into the central reject
compartment. The splash hood (Q) protects water coming over to the
effluent weir (C). The sand is returned to the sand bed through the
gravity washer/separator (G) which allows the fast settling sand to
penetrate, but not the dirty liquid. The washer/separator is placed
concentrically around the upper part of the air-lift and consists of
several stages to prevent short circuiting. By setting the reject weir
(J) below the filtrate weir (C), a steady stream flows upward,
counter-current to the sand, through the washer section, over the sand
distribution cone (P) and cleans the sand at a backwash loading rate of
50-100 gpm/ft.2. A continuous reject flow exits near the top of the
filter (K), carrying away the dirt and impurities removed in the
filter. Since the sand has a higher settling velocity than the dirt
particles, it is not carried out of the filter. The clean sand is then
redistributed after exiting the bottom of the gravity washer/separator.
The sand bed is continuously cleaned while both a continuous filtrate
and a continuous reject stream are produced.
Key Feature |
The HGSF sand filter line was originally designed
with the customer in mind. Hoffland Environmental, Inc. has overcome
the height problem that all of its competitors have. By using its
revolutionary patent pending inverse cone design, HEI can literally
save the customer money by decreasing the height of the system.
Get it right and for less the first time with the HGSF line from Hoffland Environmental, Inc.
No need for clarifier stands to gain height for gravity flow.
No need for expensive lift stations.
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Configurations |
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Applications |
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Industrial
Ground & Surface
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Municipal
Other Products by HEI
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