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Auto-Vac® Rotary Vacuum Drum Filter

The Auto-Vac® Rotary Vacuum Drum Precoat Filter (RVDF) is ALAR's flagship dewatering technology. The Auto-Vac® microfiltration design handles a wide range of volumes with various solids loadings. Its self-cleaning feature maintains consistent filtration rates without clogging, blinding or bottlenecks.

The ALAR Auto-Vac® solves environmental effluent discharge and solids disposal issues typically with less pretreatment chemicals and auxiliary capital equipment (e.g.; DAFs, Clarifiers, Sludge Settling). This system is easy to install and costs less to operate than hauling wet or liquid tonnage.

An Auto-Vac® utilizes a liquid ring vacuum pump that pulls water through a precoat drum filter while sucking moisture out of the suspended solids. The inside of the drum is hollow; the outside consists of a wedge wire screen covered by a polypropylene cloth. The drum rotates in a trough [filter pan] where one-third is submerged in liquid and two-thirds are exposed to ambient air. When activated, and before filtration, the drum surface is coated with a filter aid "cake" of Diatomaceous Earth (DE) or Perlite. This consumable filter media is porous, allowing air and water to pass through while capturing micron size particles.

Once a full cake is built on the drum, the wastewater is pumped into the pan at a controlled rate. The vacuum sucks the water [liquid] through the drum and pumps it away. Suspended solids, precipitated metals, or de-emulsified fat, oil and grease larger than one-micron will accumulate on the filter cake surface. These solids will build with each revolution of the drum until the vacuum cannot draw any more water through. At this point, a stepping motor activates a variable speed knife blade that removes the top layer of solids with lathe-like precision. The knife also shaves off a slight amount of filter aid cake as it advances toward the drum; leaving a clean layer of media to grab more solids.

The drum size, filtration rate, dryness of solids and filter aid consumption varies with the characteristics of the incoming liquid. Contact ALAR to help determine the Auto-Vac® that best suits your application.

Product Details

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ALAR custom builds sixteen (16) Auto-Vac® sizes; ranging from 3.14 to 503 square feet of filtering area. The systems are available in automatic (PLC and pneumatic control) or semiautomatic (switch and valve control) options.

The patented design features a non-segmented drum that allows 27" of vacuum to pull liquid through 100% of the filter surface. This equates to faster filtration rates, drier solids, less filter aid consumption and a smaller footprint (less square footage needed).

ALAR engineered the Auto-Vac® with variable adjustments for more efficiency. The operator can control the speed of the drum rotation and knife advance, along with the liquid level in the filter pan. Each independent function contributes to maximum effluent and dry solids quality.

The filter aid media provides "single-pass" absolute microfiltration with every revolution of the drum. When saturated with solids, the contaminated media is scraped off to expose a clean filter layer. This media protects the filter cloth from contamination by preventing direct contact with contaminated liquid. Filter aid consumption is linear to the incoming liquid volume and solids loading. ALAR will help determine the square feet of filtering area, and the amount of filter aid needed per batch. The cake layer of media will be spent after each filtration cycle (typically every 5 to 7 hours), then reapplied when the next batch cycle begins. ALAR is one of the largest distributors of bagged Diatomaceous Earth and Perlite filter aid; providing customers with competitive bulk pricing.

ALAR warehouses all major component parts; which are available for next-day delivery. This includes vacuum pumps, whereas other RVDF companies have 10 to 20 week lead times.
Contact ALAR to discover how the easy to operate Auto-Vac® can benefit your bottom line.

Auto-Vac® Sizing Rotary Vacuum Drum Precoat Filter Drum sizes are determined not by how much water is going to the Auto-Vac® filter, but by how fast the volume flows through the Auto-Vac® filter media.

The filtration rate is based upon square footage, because the filter (if flattened) is square.

The formula is:

(Gallons of Wastewater ÷ gph/ft2) ÷ Hours = ___ Ft2

ALAR has sixteen (16) filter drum sizes to choose from. The solids loading, volume and amount of hours per day will factor into the drum size needed.

The consumable filter aid precoat media is adjustable [linear] to the incoming volume. However, the filter drum should be sized to handle full-flow capacity.

Model Number Drum Diameter (Feet) Drum Length (Feet) Nominal Filtering Area
(Square Feet)
Overall Filter Skid Size
(W x L)
Overall Auxiliary Skid Size (W x L) Maximum Height (Feet) Approximate Shipping Weight (Lbs.) Total Connected Horsepower
AV110 1 1 3.1 4'-2" x 8'-1" - 6'-3" 1,900 4
AV210 2 1 6.2 6'-5" x 7'-11" - 7'-1" 2,800 6
AV220 2 2 12.6 6'-5" x 8'-11" - 7'-1" 3,000 7
AV230 2 3 18.8 6'-5" x 10'-9" - 7'-1" 3,200 9
AV240 2 4 25.1 7'-11" x 11'-11" - 7'-5" 3,400 11
AV330 3 3 28.3 8'-8" x 11'-3" - 7'-5" 5,300 13
AV340 3 4 37.7 8'-7" x 12'-7" - 8'-0" 5,500 13
AV360 3 6 56.5 9'-0" x 16'-8" - 8'-6" 6,200 20
AV640 6 4 75.4 9'-8" x 9'-9" 7'-2" x 13'-0" 8'-7" 10,100 33
AV650 6 5 94.2 9'-8" x 11'-8" 7'-2" x 13'-5" 8'-4" 11,300 48
AV660 6 6 113 9'-8" x 12'-8" 8'-1" x 14'-0" 8'-3" 11,700 48
AV690 6 9 170 9'-11" x 14'-7" 8'-5" x 18'-3" 10'-5" 14,800 69
AV6120 6 12 226 10'-1" x 17'-7" 8'-4" x 18'-9" 10'-0" 18,000 99
AV8120 8 12 302 12'-1" x 19'-0" 8'-4" x 26'-6" 10'-9" 24,300 99
AV8160 8 16 402 12'-1" x 23'-6" 10'-2" x 26'-6" 12'-1" 36,000 140
AV8220 8 20 503 12'-1" x 27'-1" 10'-2" x 29'-10" 12'-5" 41,000 140

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