What the design has to settle
Start with the cut, the flow in gallons per minute, and who will clean the screen. Then look at grease, rocks, and the power you can actually get to the site.
A coarse opening lets grit and rags through. A fine opening catches more, and it can blind if fats mat the holes. No screen on this page replaces a permit.
Bar screen
Parallel bars hold large solids. Liquid passes between them. At many receiving stations the old opening is about 3/4 inch.
A person with a rake, or a mechanical rake, clears the face. The machine is simple. The labor is not. On the pad in our industry article, that rake work can last as long as two hours.
Debris smaller than the bar gap still goes downstream. A rock trap is a separate step if the load carries stone.
Drum screen
A cylinder of perforated plate or wedge wire rotates. Flow enters the drum, or it passes in from the outside. That depends on the design.
Rotation, often with a spray or a brush, keeps the openings clear. A drum has a drive, bearings, and usually a wash-water line.
Grease and stringy solids can mat a fine drum. Plan for that before you pick a tight opening.
Vibrating screen
One or more motors shake a deck or a basket. Liquid falls through the openings. The motion carries solids off the plate.
That motion helps keep a perforated plate from blinding. Fats can still plug a fine hole. Many packaged vibrating screens want three-phase plant power.
The Muckraker is a vibrating perforated-basket screener. It is rated up to 400 gallons per minute, with 3/16 inch openings, auger compaction, and a single-phase 240V RV plug.
Bar screen vs drum screen vs vibrating screen, side by side
The rows below put a manual bar screen, a mechanically raked bar screen, a rotary drum screen, a general vibrating screen, and the Muckraker basket on the same questions: opening, who clears it, labor, wash water, power, grease, rocks, and footprint.
Scroll sideways to read every column.
| Attribute | Bar screen (manual) | Bar screen (mechanical rake) | Rotary drum screen | Vibrating screen (general) | Muckraker (vibrating basket) |
|---|---|---|---|---|---|
| How it holds solids | Parallel bars. Solids catch on the face. | Parallel bars. A rake clears the face. | A rotating perforated drum. | A motor-driven deck or basket. | A vibrating perforated basket over a tank. The model table lists an auger on the MR-4 and MR-5. |
| Typical opening | 1 to 2 in (25 to 50 mm). | 0.25 to 1.5 in (6 to 38 mm). One published septage package uses 1/4 in. | Not published as a typical range. Published specs include 5 to 10 mm and 6 mm. | Not published. | 3/16 in. |
| Who or what keeps it clear | The hauler rakes the bar rack. | A mechanical rake. | Rotation, plus spray wash or brushes. | Not published. | Vibration moves solids. The operator rinses the screens after each unload. No self-cleaning function. |
| Labor | Frequent raking increases labor costs. | Lower labor costs. High equipment maintenance costs. | Not published. | Not published. | MR-3: the operator rakes debris off a catch tray after the unload. On auger models, the operator watches for rocks that can jam the auger. |
| Raking time on a septage pad | Not published. | Does not apply. | Does not apply. | Does not apply. | Does not apply. |
| Wash water | Wash down the pad every load. | One published spec: spray wash, 20 gal/min at 60 psig. | One published spec: 40 GPM at 100 psi minimum. | Not published. | Rinse after each unload. A washdown supply is recommended, not required. No continuous wash line. |
| Power | None for the screen. | One published spec: 2 hp, 460V three-phase. | One published spec: 3 HP and 7.5 HP, 480V three-phase. | Not published for packaged screens. In one motor range, single-phase stops at 323 kg of force and larger motors are three-phase. | Single-phase 240V, about 14 amps running. Three-phase power is not required. |
| Grease and rag blinding | Not published. | One maker states that its rake prevents plugging and blinding from grease. | Perforated holes can blind when rags and trash are heavy. | Not published. | An optional diversion plate keeps clumpy grease out of the auger. Tested FOG results: Not published. |
| Rocks and grit | Grit removal is a separate step. | A separate rock trap. | A separate rock trap. | Not published. | Rocks and bolts can jam the auger. The operator watches for them. |
| Screenings dewatering | None. Screenings are raked off. | One maker states a screw press at 40 to 50 percent dry solids. | A wash press. | Not published. | Auger compaction on the MR-4 and MR-5. The manual also lists the auger under optional accessories. The MR-3 has no auger. The MR-6 uses a conveyor. |
| Truck unload time | Not published. | About 10 minutes in one published description. | 5 to 15 minutes in one published description. | Not published. | 10 to 15 minutes at 400 GPM. |
| Footprint and install | Concrete pad, inlet, and trash rack. | One published tank, minimum: 4.08 ft wide, 7.25 ft long, 4.83 ft high. | One published drum: 3.94 ft in diameter, 9.24 ft long. One proposal quotes delivery at 22 to 30 weeks. | Not published. | About 12 ft by 12 ft. About 1 hour from unload to the first truck when site prep is already done. |
| Mobility | Described on a fixed pad. | Published options include a skid-mounted design and a trailer-mounted demo. | Not published. | Not published. | Trailer mounting is allowed when a jack is at each corner. |
Openings and what gets through
A typical manual bar opening is 1 to 2 in (25 to 50 mm). A typical mechanically raked bar opening is 0.25 to 1.5 in (6 to 38 mm). Those ranges are in EPA's screening fact sheet, EPA 832-F-03-011. One published septage package uses 1/4 in bar spacing. Published drum openings include 5 to 10 mm and 6 mm. A typical opening for a general vibrating screen: Not published. The Muckraker basket is 3/16 in. Solids smaller than the opening still go downstream. A finer opening holds more of those solids, and fats can still plug a fine hole.
Who keeps it clear
On a manual bar screen, the hauler rakes the rack. That frequent raking increases labor costs. A mechanical rake clears the face, with lower labor costs and high equipment maintenance costs. A drum uses rotation, often with a spray wash or brushes. Who keeps a general vibrating screen clear: Not published. On the Muckraker, vibration moves the solids, and the operator rinses the screens after each unload. The screens have no self-cleaning function. On the MR-3, the operator also rakes debris off a catch tray after the unload.
Power, water and footprint
A manual bar screen has no power requirement of its own, and the pad is washed down every load. One published mechanical package uses a 2 hp, 460V three-phase drive and a spray wash of 20 gal/min at 60 psig. One published drum package uses 3 HP and 7.5 HP drives at 480V three-phase, and wash water of 40 GPM at 100 psi minimum. Wash water and plant power for vibrating screens as a group: Not published. In one motor range, single-phase vibratory motors stop at 323 kg of force and the larger motors are three-phase. The Muckraker uses a single-phase 240V supply at about 14 amps running, and three-phase power is not required. The operator rinses the screens after each unload. A washdown supply is recommended and not required. The unit is about 12 ft by 12 ft, and setup is about 1 hour from unload to the first truck when site prep is already done.
Which screen fits your receiving pad
Hauler pad or depot
A hauler pad has to match the power on site, whether the screen stays put or can move, and how long a truck sits. EPA's receiving guide describes a manual bar rack on a concrete pad, with an inlet and a trash rack, and the hauler rakes that rack. Raking time: Not published. Published mechanical options include a skid-mounted design and a trailer-mounted demo. The Muckraker runs on single-phase 240V. Trailer mounting is allowed when a jack is at each corner. A truck unloads in 10 to 15 minutes at 400 GPM. Station layout is part of planning an automated septage receiving solution.
Plant headworks
The screen holds solids. Grit removal is a separate step, and published mechanical and drum packages add a separate rock trap. The Muckraker is not designed to remove grit. Rocks and bolts can jam the auger, and the operator watches for them. Ratings for this basket are on the published wastewater vibratory screener ratings page.
Municipal receiving station
U.S. EPA receiving-station guidance lists five parts: a dump point, screening, grit removal, storage, and odor control. A screen is the screening part. The Muckraker is the dump point and the screen. The model table lists an auger on the MR-4 and MR-5. It does not include flow metering, hauler authentication, transaction tracking, a grinder, or a receiving tank. Grit removal, storage, and odor control stay separate from the screen.
What no screen does on its own
None of these screens removes grit. A rock trap or a grit chamber is a separate step. A screen does not replace a permit. On the MR-4 and MR-5, an auger compacts what the basket holds. The manual also lists an auger system under optional accessories. The MR-3 has no auger. The MR-6 uses a conveyor. For compacted solids, see the paint filter test for dewatered screenings are a separate check from the screen type. Pad and power steps are in the pad and power prep steps. Bar screen raking on a receiving pad is described in the article on receiving station bar screens.
Station layout, power, and hauler access are on the septage receiving station guide. Published machine specs are on the Muckraker septage screener page.