Filter presses for dredged river and harbour sediment, TBM and bentonite drilling mud and oily sludge: separation before filtration, geotextile tubes vs mechanical dewatering.

Filter Presses for Dredged Sediment and Drilling Slurry

Quick answer: Dredging and drilling produce the most variable feed a filter press ever sees — sand, silt, clay, debris and sometimes oil, in proportions that change hour to hour. The press is rarely the hard part. Separation upstream of it, and conditioning, decide whether the installation works.

Separate before you dewater

Sending raw dredge slurry or used drilling mud straight to a filter press wrecks pumps, cloth and plate sealing faces. The standard sequence removes coarse material first:

  • Debris screening — wood, stone, metal and rubbish from harbour and river sediment.
  • Sand separation — hydrocyclones or shaker screens, so abrasive coarse fraction never reaches the press.
  • Thickening — the remaining fines fraction is what the press is sized for.

Only the fine fraction justifies filtration. Contractors who skip this step usually conclude that filter presses “do not work” on dredge material; what failed was the flowsheet.

Geotextile tubes or a filter press?

Both are used in dredging, and they answer different questions. Geotextile tube dewatering is cheap to mobilise, needs a large laydown area and a long dewatering time, and leaves you with tubes to dispose of. A filter press is a capital item that produces a stackable cake continuously in a small footprint, with predictable output.

The choice usually comes down to project duration, available land and whether the sediment is contaminated. Short campaigns with space favour tubes; long or space-constrained projects, and contaminated sediment needing consistent, verifiable cake, favour mechanical dewatering.

Drilling mud and bentonite slurry

TBM and foundation work generates bentonite slurry that is deliberately engineered not to lose water — that is what it is for. Dewatering it therefore means breaking the very property the mud was designed around, which is a conditioning problem before it is a machine problem.

See bentonite slurry and TBM drilling mud and oil and gas drilling and frac fluid.

Oily sludge

Where hydrocarbons are present, oil coats cloth fibres and blinds them in a way that washing does not fully reverse. Cloth polymer choice, wash regime and sometimes a pre-treatment step become the whole problem.

See filter presses for oily sludge.

Sand, aggregate and stone slurry

The same separation-then-filtration logic applies to sand washing and stone cutting operations, where water recovery is usually the driver.

See stone industry and marble and granite cutting slurry.

Equipment

Frequently asked questions

Can a filter press handle dredged sediment directly?

Not reliably. Remove debris and sand first. With separation upstream, the fine fraction dewaters well; without it, you will replace cloth and pump parts constantly.

What happens to the filtrate?

On contaminated sites it usually needs treatment before discharge — suspended solids, metals or hydrocarbons depending on the sediment. Plan for that stage in the flowsheet, not as an afterthought.

Is mobile or skid-mounted equipment practical?

Yes, and it is common on dredging projects because the work moves. It changes how the plant is laid out and connected rather than how the filtration itself works.

Why does my cycle time collapse after a few weeks on drilling mud?

Usually bentonite progressively blinding the cloth, sometimes combined with oil. It is a cloth selection and wash problem; see what causes cloth blinding.

Dredge and drilling feeds vary too much to size from a description — send a representative sample and we will run a filtration test. See filtration testing and trials, or contact us.