By Senjie Filter Press Engineering Team · Last updated: 2026-09-14
Quick answer: A chamber or membrane filter press dewaters palm oil mill effluent (POME) sludge from 4 to 6% solids to a 55 to 65% moisture cake in 2 to 3 hour cycles. A 60 t FFB/h mill typically needs 150 to 250 m² of filter area with 1000 to 1250 mm PP plates rated to 90 °C and monofilament PP cloth.
Palm oil mills in Indonesia and Malaysia generate 0.6 to 0.8 m³ of POME for every tonne of fresh fruit bunches (FFB) processed. The sludge that settles in anaerobic ponds is oily and fibrous and fills ponds faster than mills can desludge them. This guide covers belt press and decanter comparisons, plate and cloth selection, sizing per tonne of FFB per hour, and cake reuse. Product details are on the chamber filter press page.
What are the characteristics of POME sludge that affect dewatering?
POME sludge is hot (80 to 90 °C at the sterilizer and clarifier outlet), oily (4,000 to 10,000 mg/L oil and grease in raw effluent), fibrous, and contains 4 to 6% total solids after pond settling, with a raw BOD of 20,000 to 30,000 mg/L and a pH of 4 to 5.
Raw POME carries palm fibre, cell debris, sand and free plus emulsified oil. Anaerobic ponds settle this into a bottom sludge of 4 to 6% solids, sometimes 8% in older ponds, at 28 to 35 °C, pH 6.5 to 7.5 and 1 to 3% oil on a dry solids basis.
Oil coats filter media and reduces free drainage. Fibre gives the cake a structure that releases well from a filter press but blinds a belt press, and a 2 to 3 mm pre-screen protects the feed pump.
Why do belt presses struggle with POME sludge?
Belt presses struggle with POME because oil and fine fibre blind the belt within hours, the low pressure of 0.1 to 0.3 MPa leaves cakes at 75 to 82% moisture, and the open belt sprays oily filtrate and needs 5 to 10 m³/h of wash water.
A belt press depends on gravity drainage, and POME drains slowly because oil fills the pores between fibres. Operators respond with 8 to 15 kg of polymer per tonne of dry solids and still see cake at 75% moisture or wetter. A filter press instead uses 0.6 to 1.0 MPa feed pressure to force liquid through the cake itself, so the cake becomes the filter medium. The result is a 55 to 65% moisture cake that drops cleanly from the cloth, with 0 to 4 kg/t of polymer if the pond sludge is well digested.
Decanter centrifuge vs filter press for POME: which is better?
A decanter centrifuge is better where the mill needs continuous sludge removal at 15 to 30 m³/h with minimal labour and accepts a 70 to 78% moisture cake; a filter press is better where the target is a 55 to 65% moisture cake for composting, energy of 15 to 30 kWh per tonne of dry solids, and simple maintenance.
| Criterion | Chamber filter press | Membrane filter press | Decanter centrifuge | Belt press |
|---|---|---|---|---|
| Cake moisture | 60–65% | 55–60% | 70–78% | 75–82% |
| Operation | Batch, 2–3 h cycle | Batch, 1.5–2 h cycle | Continuous | Continuous |
| Energy, kWh/t dry solids | 15–25 | 20–30 | 40–70 | 10–20 |
| Polymer, kg/t dry solids | 0–4 | 0–4 | 4–8 | 8–15 |
| Sand and grit tolerance | High | High | Low (scroll wear) | Medium |
| Cake handling | Solid, stackable | Solid, stackable | Pasty | Pasty |
Decanter and belt press cakes are too wet to compost without adding empty fruit bunch (EFB) fibre at 1:1 or more. The trade-offs on mineral duty are covered in the article on filter press vs decanter centrifuge.
Which filter plates and cloth are suitable for hot, oily POME sludge?
Polypropylene chamber plates rated to 90 °C in 1000 to 1250 mm sizes, fitted with monofilament PP cloth of 400 to 800 micron nominal rating, are the standard specification for POME sludge, because they resist the pH 4 to 7.5 range and release oily cake cleanly.
If the press takes sludge directly from the clarifier at 80 to 90 °C, glass-reinforced PP plates rated to 120 °C are the safer choice. Most mills press pond sludge at 28 to 35 °C, so standard PP filter plates with a 32 mm chamber are the common choice.
Multifilament PP cloth traps oil and fine fibre in its yarn bundles and cannot be washed clean. Monofilament PP cloth has a smooth single-strand weave that oil does not penetrate, so a 1.0 MPa wash every 10 to 20 cycles restores flow. Expected cloth life is 6 to 12 months; sand from poorly maintained desanders shortens this to 3 to 6 months. Options are on the filter press cloth page. A progressing cavity pump behind a 3 mm screen gives the smooth ramp to 1.0 MPa that helps oily cake form evenly.
What cake moisture can a filter press achieve on POME sludge?
A chamber filter press achieves 60 to 65% cake moisture on anaerobic pond POME sludge, and a membrane filter press with 1.5 MPa squeeze achieves 55 to 60%, compared with 70 to 82% from a decanter or belt press.
Well-digested pond sludge dewaters 5 to 8 percentage points drier than fresh clarifier sludge. Extending feed from 90 to 150 minutes adds 2 to 4 points of dryness on a chamber press. Membrane squeeze at 1.5 MPa for 10 to 15 minutes removes a further 5 points and shortens the cycle to 1.5 to 2 hours. Air blow-through is not recommended because oil makes the cake seal and channel.
How do you size a POME filter press per tonne of FFB per hour?
Allow 2.5 to 4 m² of filter area per tonne of FFB per hour of mill capacity for 20 hours of mill operation and 6 to 8 press cycles per day; a 60 t FFB/h mill therefore needs 150 to 250 m², typically one 1250 mm press with 60 to 90 plates.
Pond sludge accumulates at roughly 0.6 to 0.8 kg of dry solids per tonne of FFB, so a 60 t/h mill running 20 hours a day generates 800 to 1,200 kg of dry solids per day, plus any backlog from undesludged ponds.
| Mill capacity | Dry solids per day | Wet cake at 60% moisture | Filter area | Typical press | Cycles per day |
|---|---|---|---|---|---|
| 30 t FFB/h | 400–600 kg | 1.0–1.5 t | 60–100 m² | 800 mm × 50–70 plates | 4–6 |
| 60 t FFB/h | 800–1,200 kg | 2.0–3.0 t | 150–250 m² | 1250 mm × 60–90 plates | 6–8 |
| 90 t FFB/h | 1,200–1,800 kg | 3.0–4.5 t | 250–350 m² | 1250 mm × 90–110 plates or 1500 mm | 6–8 |
These areas allow a pond backlog to be cleared in 12 to 24 months; for current production alone the area can be halved. Plate counting is explained in the guide on how to calculate filter press capacity.
What can the POME filter cake be used for?
POME filter cake at 55 to 65% moisture is used as compost feedstock, blended with empty fruit bunch fibre and boiler ash, and applied to oil palm plantations as an organic fertiliser containing roughly 2 to 3% nitrogen, 0.5 to 1% phosphorus and 2 to 4% potassium on a dry basis.
Malaysia limits POME discharge to 100 mg/L BOD for most mills, and Indonesia sets 100 mg/L BOD and 250 mg/L COD; desludging ponds keeps anaerobic retention time within those limits. Guidance on safe use of dewatered organic sludge is published by the US EPA in its biosolids programme; the same principles apply to POME cake.
Filter press cake composts in 4 to 8 weeks when windrowed with EFB at 1:1 to 1:2. Filtrate, at 3,000 to 8,000 mg/L BOD, returns to the anaerobic pond or biogas plant.
Why buy a POME sludge filter press from Senjie?
Senjie is a China-based manufacturer of chamber, membrane and fully automatic filter presses, filter plates, filter cloth and feed pumps. Changzhou Senjie Environmental Equipment Co., Ltd. has built filter presses since 2014 and exports to more than 40 countries, with Indonesia, Malaysia, Vietnam and the Philippines among its main Southeast Asian markets.
For palm oil mills, Senjie supplies 800 to 1500 mm PP and glass-reinforced PP plate presses with 25 to 32 mm chambers, monofilament PP cloth, feed pumps and PLC-controlled automatic plate shifting and cloth washing, with sizing support and a factory test run. Typical lead time is 25 to 45 days.
Send your mill capacity, pond volume and a sludge sample analysis to the Senjie engineering team for a sizing proposal and quotation.
Frequently Asked Questions
Can a filter press handle POME sludge at 80 to 90 °C?
Yes, if the plates are specified for it. Standard PP plates are rated to 90 °C, so glass-reinforced PP plates rated to 120 °C are recommended for feed above 80 °C. Pond sludge at 28 to 35 °C suits standard PP plates.
What cake moisture does a filter press achieve on POME sludge?
A chamber filter press achieves 60 to 65% cake moisture on digested pond sludge, and a membrane press with 1.5 MPa squeeze achieves 55 to 60%, compared with 70 to 82% from a decanter or belt press.
How big a filter press does a 60 t FFB/h palm oil mill need?
A 60 t FFB/h mill needs about 150 to 250 m² of filter area, typically one 1250 mm chamber press with 60 to 90 plates running 6 to 8 cycles per day. This handles 800 to 1,200 kg of dry solids per day.
Which filter cloth is best for oily POME sludge?
Monofilament polypropylene cloth with a 400 to 800 micron nominal rating is best. Oil does not penetrate the single-strand yarn, so a 1.0 MPa wash every 10 to 20 cycles restores flow.
Is polymer needed to dewater POME sludge on a filter press?
Often not. Well-digested pond sludge dewaters with 0 to 4 kg of polymer per tonne of dry solids, and many mills run without any. Fresh clarifier sludge may need 2 to 4 kg/t of cationic polymer.