Filter press

A performant, efficient and cost effective solid-liquid separation.

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What is it?

Filter press is a solid liquid separation technique, typically applied to sludge produced on an effluent treatment plant.

It consists of pumping the sludge, typically at a concentration of ~50g/l (0.5%), at a pressure between 6 and 18 bar, to a filter press.

A filter press is made of a series of plates, usually in polypropylene, which are covered by a filtration cloth, also typically in polypropylene thus creating chambers between each plate where the solids are retained and gradually dewatered under the pressure from the feed pump.

The resulting dry matter content of the sludge cake depends on the type of sludge, the quality of the flocculation and the operating pressure.

Metal hydroxide sludge at 13 bar and over can reach 35% to 40%, sludge with high calcium content (calcium carbonates, calcium sulphates etc.) can reach 60% dry matter content.

The filtrated water, whilst usually compliant, is typically returned to the clarified water processing or the inlet of the effluent plant.

The produced sludge cake can either be collected in a skip placed under the press or on a conveyor to be directed to a skip.

Automated filter press on platform

Nowadays, filter presses offer many options :

  • Double acting hydraulic pack for the closing and opening of the press
  • Core blow
  • Actuated drip tray
  • Automated plate movement (this greatly facilitates the task of the operator)
  • Automated plate shaking system
  • Automated plate weighing system (Technology covered by patent, allows continuous press operations without the presence of an operator)
  • Automated plate washing

Review the fully automated emptying sequence of a press we recently installed :





"I would highly recommend Puretech Environmental as they provide excellent solutions, service and are always available to help you. The people are very well skilled and passionate about what they do, and this is clearly seen in their work - Five start rating"

Aidan Kelly | Thermo-King - Group Leader
What makes


... by the range of industrial pollutions we can address : pH, heavy metals, cyanides, hexavalent chromium, BOD, "Hard" COD, Fat Oil & Grease, suspended solids, sulphates, phosphorous, nitrates, Ammonia, and anything you can think of to challenge us.

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... by picking the right technology for the right problem to provide the client with a guarantee of performance. Here are some of the processes we cover : Coagulation, Neutralisation, Flocculation, Oxidation, Reduction, Flotation, Settlement, Filter press, Screw press, Centrifuge, Ion exchange resin, Membranes technologies etc.

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Case studies

... Solving tricky problems for our customers is what gives us the edge and the enjoyment - We relish a challenge. Explore our case studies of previous projects

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