Rotary Drum Filter — Gravity-Driven Filtration from 10 μm to 2.5 mm, Internal or External Feed
A rotary drum filter is a self-cleaning fine filter: a rotating drum covered in fine mesh panels turns continuously in the liquid, water passes through the mesh, and the captured solids are washed off by an automatic backwash spray before they can blind the surface. Gravity does the separation and plant water does the cleaning, so the list of powered duties stays short — which is why the rotary drum filter has become the standard polishing and pre-treatment machine on municipal and industrial wastewater, aquaculture recirc systems and food processing water loops. The LWRD range covers that job in two series — a standard series rated 20 micron to 2.5 mm and a precision series for 10–20 micron polishing — each available with internal-feed or external-feed construction to match the solids in your water.
Rotary Drum Screen, Drum Filter or Vacuum Drum Filter?
These three machines get mixed up more often than they should — they all rotate, they are all cylindrical, and the same word gets used for more than one of them. The real difference is what each one does to the solids.
Rotary drum screen
A coarser rotating screen for removing trash, fibres and debris — intake protection, primary screening and protection of downstream units such as MBR systems.
Typical role: first line of defence before finer treatment.
See the rotary drum screen page →Rotary drum filter
A rotary drum filter is a self-cleaning fine filter working the 10 μm – 2.5 mm band in two series, gravity-fed, with no vacuum and no cloth. Solids are held on the mesh and washed off — the goal is clear water, not a dry cake.
Typical role: TSS polishing on municipal and industrial wastewater, RAS solids control, process-water loops.
You are on this pageRotary vacuum drum filter
A vacuum-assisted drum that pulls liquid through a cloth and forms an actual cake. Different job: it concentrates high-solids slurries instead of polishing large flows of dilute water.
Typical role: slurries and dewatering — a different selection conversation.
Compare separation technologies →In practice the boundary is the mesh and the duty: if your liquid is a large flow with dilute suspended solids and the target is clean water, you are in rotary drum filter territory; if it is a thick slurry that must leave as a cake you can handle, the vacuum or filter-press route fits instead. If you arrived searching for a drum screen, that machine is on its own page — both are built at the Loway works, so either can be sized against your duty.
Fine Filtration Is Its Own Band — Where This Machine Sits
Every solid-liquid separation step has a particle range it handles best. A rotary drum filter works the band between coarse screening and membrane filtration: mesh ratings from 10 microns up to 2.5 mm, at flows that would make a filter press impractical — and a rotary drum filter serves that band without ever stopping. The LWRD range covers it in two series: standard, 20 μm – 2.5 mm, and precision, 10–20 μm.
Rotary Drum Filter Working Principle: Filter, Ride Out, Wash, Repeat
The cycle runs continuously while the drum turns. A rotary drum filter never shuts down to clean itself — the washing zone and the filtering zone exist at the same time, on different parts of the same rotating surface.
Internal Feed or External Feed — Built to Match Your Solids
The same drum, mesh and backwash are available in two feed arrangements. The difference is which side of the mesh does the filtering, and it is decided by what your water carries.
Water enters inside the drum
Feed flows axially into the drum; filtered water passes outward through the mesh and solids collect on the inner surface, where the spray washes them into an internal collection trough. A compact footprint, often with a screw-assisted discharge inside the drum.
Typical duty: algae and floating-matter removal on raw water, RAS aquaculture, fine TSS polishing on municipal and industrial wastewater. Head loss: 50–150 mm — the lower of the two, so civil works stay shallow. Note: on very high solids loads, material can accumulate inside the drum — flagged from your feed analysis.
Water flows in from outside
Feed flows around the outside of the drum and filtered water passes inward into the drum core; solids collect on the outer surface, are washed off at the top and drop into a discharge hopper below. Fewer parts sit in the water and cleaning access is simpler.
Typical duty: hair, fibre and pulp-carrying effluent — paper-mill, slaughterhouse, textile and MBR pre-protection run best on this arrangement. Head loss: 80–180 mm. Note: hard coarse particles can strike the mesh — a coarse pre-screen upstream is advised.
Both arrangements are built at the Loway works. Send the feed analysis and we will confirm which construction your duty takes.
Six Parts Do All the Work
A rotary drum filter has no cloth to tension, no vacuum system and no pumps in the process stream. On wastewater duty that decides more than anything else: availability comes down to six components, and all six are accessible from outside the tank.
Mesh panels
The rotary drum filter medium: wedge-wire or woven mesh panels clamped around the drum in sections, rated from 10 microns to 2.5 mm depending on the series. Panels are changed individually, so a rating change is a maintenance job, not a rebuild.
Backwash spray bar
A spray bar above the drum washes each panel the moment it leaves the liquid. Nozzles are outside the process, so they stay serviceable without draining the tank.
Solids trough
The washed-off solids fall into a trough that carries them out of the machine. It is open and visible — you can see what the filter caught.
Tank, seals and weirs
The stainless tank sets the liquid level around the drum. Seals between drum and tank keep the flow going through the mesh instead of around it.
Drum drive
One geared drive turns the drum at low speed — typically 1–4 r/min, with variable-frequency control where the load swings.
Level control and PLC
A level sensor in the tank starts and stops the drum and backwash automatically as the load changes, with overload protection and alarms — the machine runs unattended.
Three Duties Where a Rotary Drum Filter Is the Default Choice
Municipal and industrial wastewater
Polishing after primary treatment, or pre-treatment ahead of biological stages and dewatering equipment. On municipal and industrial wastewater the rotary drum filter strips the suspended load that would otherwise be carried into the next process, and runs unattended as part of the plant’s front line.
Aquaculture and RAS
Recirculating systems live on this machine: it takes out feed waste and faecal solids continuously, which is what keeps oxygen demand down and fish healthy. Fine mesh ratings and gentle flow handling are the reasons RAS designers specify a rotary drum filter rather than a coarse screen.
Food and process water
Wash water loops, effluent with recoverable solids, and closed process streams that must stay clean and enclosed. A 316L build and a fine mesh rating are what let a rotary drum filter hold this kind of duty. Send the water analysis and we will confirm the rating.
Four Inputs Decide the Machine
A rotary drum filter is sized from your duty. The LWRD series runs from 20 to 1,250 m³/h (480 to 30,000 m³/d) across two series; which one your project lands on — and what the machine is built from — comes from four inputs.
Flow and loading
Daily flow, peak flow and how steady it is. Sizing starts here — a steady low flow and a storm peak lead to different answers.
Solids in the feed
TSS concentration and what the particles are. Fibrous, gritty and biological solids behave differently on the same mesh.
Mesh selection
The rating that meets your water quality target while still releasing during backwash. The rating is confirmed against your feed and your water-quality target.
Material and site
304 as standard, 316L where corrosion calls for it. Plus what surrounds the machine: indoor or outdoor, winterising, layout constraints.
Two series cover that span — a single compact rotary drum filter on a fish farm through to multi-drum trains on municipal and industrial works. The model for your project is confirmed against your flow, your TSS and the site conditions.
LWRD precision series — 10–20 μm, high-flow polishing
| Model | Flow (m³/d) | Flow (m³/h) | Filter area (m²) | Drum (mm) | Overall L × W × H (mm) | Inlet / outlet | Drive (kW) | Backwash pump (kW) | Backwash (bar) |
|---|---|---|---|---|---|---|---|---|---|
| LWRD-2000 | 1,000–2,500 | 42–104 | 1.5 | Ø1,000 × 1,000 | 2,500 × 1,400 × 1,800 | DN200 | 0.55 | 1.5 | 6–7 |
| LWRD-3000 | 2,500–4,000 | 104–167 | 1.8 | Ø1,200 × 1,200 | 2,700 × 1,600 × 2,000 | DN250 | 0.55 | 2.2 | 6–7 |
| LWRD-5000 | 4,000–6,000 | 167–250 | 3.0 | Ø1,300 × 1,500 | 3,000 × 1,700 × 2,200 | DN350 | 0.75 | 3.0 | 6–7 |
| LWRD-10000 | 6,000–10,000 | 250–417 | 6.0 | Ø1,400 × 2,500 | 4,000 × 1,800 × 2,300 | DN500 | 0.75 | 4.0 | 6–7 |
| LWRD-15000 | 10,000–15,000 | 417–625 | 9.0 | Ø1,400 × 3,000 | 4,500 × 1,800 × 2,300 | DN600 | 1.1 | 4.0 | 6–7 |
| LWRD-20000 | 15,000–20,000 | 625–833 | 12.0 | Ø1,400 × 4,500 | 6,000 × 1,800 × 2,300 | DN700 | 1.5 | 5.5 | 6–7 |
| LWRD-25000 | 20,000–25,000 | 833–1,042 | 15.0 | Ø1,500 × 4,600 | 6,100 × 1,900 × 2,500 | DN700 | 1.5 | 5.5 | 6–7 |
| LWRD-30000 | 25,000–30,000 | 1,042–1,250 | 18.0 | Ø1,500 × 5,500 | 7,000 × 1,900 × 2,500 | DN800 | 1.5 | 7.5 | 6–7 |
Nominal series figures for 10–20 μm media at 6–7 bar backwash pressure. The model, media rating and materials of your rotary drum filter are confirmed against your flow, your TSS and the site conditions before the proposal is issued.
LWRD standard series — 20 μm – 2.5 mm, general-duty fine filtration
General parameters — both constructions
| Parameter | Range | Notes |
|---|---|---|
| Filtration principle | gravity screening | no vacuum, no negative pressure, no feed pump |
| Mesh media | wedge-wire or woven mesh | panel-built, sections changed individually |
| Material | SS304 / SS316L | 316L for seawater and corrosive effluent |
| Filtration rating | 20 μm – 2.5 mm | common ratings: 50, 80, 100, 150 μm; finer 10–20 μm on the precision series |
| Control | PLC + level sensor | automatic start/stop, fault alarm, optional remote signal output |
| Backwash medium | filtered plant water | normally recycled to the head of the plant |
| Backwash pressure | 0.3–0.4 MPa | precision series runs 6–7 bar |
| Backwash consumption | 0.5–3% of throughput | automatic — filtration continues during washing |
| Drum speed | 1–4 r/min | variable-frequency drive |
| SS removal | 60–95% | depends on feed TSS and mesh rating |
Internal-feed models
| Model | Drum Ø × L (mm) | Flow (m³/h) | Drive motor | Head loss |
|---|---|---|---|---|
| LWRD-600 | Ø600 × 1,000 | 20–75 | 0.37 kW | 50–150 mm |
| LWRD-800 | Ø800 × 1,500 | 50–250 | 0.55 kW | 50–150 mm |
| LWRD-800L | Ø800 × 2,000 | 80–400 | 0.75 kW | 50–150 mm |
External-feed models
| Model | Drum Ø × L (mm) | Flow (m³/h) | Drive motor | Head loss |
|---|---|---|---|---|
| LWRD-600 | Ø600 × 1,000 | 30–80 | 0.37 kW | 80–180 mm |
| LWRD-800 | Ø800 × 1,200 | 80–160 | 0.55 kW | 80–180 mm |
| LWRD-1000 | Ø1,000 × 1,400 | 160–260 | 0.75 kW | 80–180 mm |
Flows are rated on clean water at low feed TSS; actual wastewater capacity falls with feed solids and fibre load, and larger non-standard drum sizes are available. The model, mesh rating and materials of your rotary drum filter are confirmed against your flow, your TSS and the site conditions before the proposal is issued.
Why the Running Cost Stays Low
Water flows through the mesh under head, not under pump pressure. There is no vacuum system to run, which is the largest single difference between this machine’s operating cost and a vacuum drum filter’s — a vacuum unit pays continuously to pull a cake; here the only powered duties are turning the drum and running the backwash pump.
Backwash runs automatically as the drum turns, using plant water. Nobody opens the machine to clean the mesh, so the labour line stays near zero and a rotary drum filter never stops for cleaning.
Mesh panels, spray nozzles and seals — that is the wear list. Panels are changed section by section without dismantling the drum, and nozzles sit above the water line where they can be serviced in minutes. Wear parts are stocked at the Loway parts page.
What a Rotary Drum Filter Does — and Does Not — Do
Honest scope, because the machine is often miscast. A rotary drum filter removes suspended solids — that is the whole job, and within that job it is excellent. Four boundaries to know before you specify one.
Dissolved pollution passes through
Suspended solids are what the mesh catches. Dissolved COD, ammonia and colour need biological or chemical treatment downstream — a rotary drum filter is pre-treatment and polishing, not a treatment plant in itself.
Grease and sticky solids blind the mesh
Oils and sticky sludge coat the mesh faster than the backwash can clear it. Where the feed carries them, the build is specified with more frequent backwash or an upstream grease trap — flagged from your water analysis, not discovered on site.
Colloids are too small for any mesh
Very fine colloidal particles pass straight through a micron-rated panel. When water must go clearer still, the rotary drum filter is usually the guard that protects the settling stage or membranes doing that final work.
Mesh is a wear part
Abrasive feeds wear panel wire over time. Panels are changed section by section without dismantling the drum, and wear parts are stocked so the wear never becomes downtime.
Rotary Drum Filter Manufacturer: How Loway Builds the Machine
Frequently Asked Questions
What determines the price of a rotary drum filter?
Four inputs set the quotation: flow, solids loading, mesh rating and material of construction. Send us what you have from your process data and we will return a priced technical proposal.
How does a rotary drum filter work?
A rotating drum covered in fine mesh panels turns in the liquid. Water passes through the mesh, solids stay on the surface, and an automatic backwash spray washes them into a collection trough as each panel leaves the liquid. Filtration and cleaning happen at the same time, so the flow never stops.
Which applications fit this machine best?
A rotary drum filter fits continuous flows with dilute suspended solids, from compact single units to large municipal trains: wastewater polishing and pre-treatment, RAS aquaculture, and food or process-water loops. Where the feed is a thick slurry that must leave as a dry cake, a filter press or vacuum unit is the better route — we confirm the match against your duty before quoting.
Which mesh sizes are available?
Rotary drum filter mesh is rated from 10 microns to 2.5 mm across the two LWRD series: 20 μm – 2.5 mm on the standard series and 10–20 μm on the precision series, selected against your solids and water-quality target. Ratings are panel choices, so they can be changed later if your process changes.
Does a rotary drum filter need a vacuum pump?
No. This machine is a gravity screen filter — water passes through the mesh under a small head difference and there is no vacuum system in it at all. It is a different machine from the rotary vacuum drum filter, which pulls a cake against a cloth under vacuum for dewatering duty.
Can the mesh panels be replaced individually?
Yes. The mesh is built in sections clamped around the drum, so a damaged or worn panel is changed on its own without dismantling the drum — and a rating change is a panel swap, not a rebuild.
Internal feed or external feed — which construction do I need?
The feed arrangement follows the solids: high-fibre feeds such as paper-mill, slaughterhouse and textile effluent run best on the external-feed build, where solids collect on the outside of the mesh and cleaning access is simplest. Lower-solids polishing and RAS duty usually takes the internal-feed build. We confirm the arrangement from your feed analysis.
How much backwash water does the machine use?
On the standard series, backwash consumes 0.5–3% of the treated flow, using filtered plant water at 0.3–0.4 MPa, and the wash water is normally recycled to the head of the plant.
What maintenance does the machine need?
The wear list is short: mesh panels, spray nozzles and seals. Nozzles sit above the water line and panels are changed section by section without dismantling the drum. Common wear parts are stocked for fast shipment — see the parts page.
What information should I send to size one?
Flow rate, TSS concentration, the application and the installation conditions (indoor or outdoor, climate, space limits). Those four inputs are enough for a first rotary drum filter proposal; the rest is refined during detailed engineering.
What warranty and support come with the machine?
Warranty terms are stated clearly in every quotation. As the manufacturer we support the machine directly: commissioning guidance, lifetime technical contact by email, phone and video, and stocked replacement parts so a worn panel or nozzle does not stop your plant.
Send Us Your Flow, Your TSS and Your Duty
A sized proposal for a rotary drum filter starts with four numbers from your process. Send what you have — as the manufacturer we will come back with a machine that fits your wastewater duty, or with the one question that needs answering first.
Complete the Treatment Line
Rotary Drum Screen
Coarser screening for intake protection and pre-treatment — the upstream sibling of this machine.
Belt Filter Press
Continuous sludge dewatering — often the step the drum filter protects.
Dewatering Screw Press
Low-maintenance sludge dewatering for compact plants.
Membrane Filter Press
Batch dewatering to the driest cake in the range.
Mobile Filter Press
Dewatering capacity that travels between sites.
Spare Parts & Accessories
Mesh panels and nozzles for this machine, cloths and seals for the dewatering line — stocked wear parts.