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Sludge Catch

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“SLUDGE CATCH” – Equipment for Sludge Dewatering

Amalgam Engineering
The sludge dewatering system uses disposable/reusable bags. The special filtration bag made from water repellent material is mounted on stainless steel frame designed to give even sludge distribution. This system is modular and optimizes the dewatering cycle.

SLUDGE CATCH dewaters the sludge from water and waste water treatment plants using special filtering bags. The bags are made from special water repellent material which allows one way flow of water from inside to outside. The system can be optionally supplied with programmable control panel ensuring correct operation.

The flocculated and conditioned sludge is continuously fed to the unit at a steady rate. The flocculated solids are retained inside the bags and the free water is continuously drained out.

As soon as the level of solids in the bags have reached the predetermined level, the feed to the unit is stopped and the bags are allowed to stand as such for some time to enable the free water to drain out.

After this initial dewatering the bags are sealed and removed using a special trolley and stored in the open. During this second phase of open-air storage time the sludge weight and volume continue to reduce irrespective of the weather conditions. The special water repellent material of the bags prevents the rain water from entering but allows dehydration of the content by evaporation. After storage of about 10 – 15 days, depending on the ambient conditions a cake of 50 -95{a4503f35f1adc3483e439b6462ef5853fd64d4b5b45a0b84a6e383b1a237e74c} dry solids is obtained.


The volume of the sludge handled depends on the solid content in the feed and the type of sludge. Typically the units can handle a flow rate of 20m3/day with 1{a4503f35f1adc3483e439b6462ef5853fd64d4b5b45a0b84a6e383b1a237e74c} solid content. Various models are available viz.1, 2, 3&6 bags model. Multi models can be installed either in series and parallel in order to obtain the desired final conditions.


Salient Features

  • Bags designed to allow unidirectional flow of water
  • Two step dewatering process. One by gravity and other natural evaporation
  • 50-95{a4503f35f1adc3483e439b6462ef5853fd64d4b5b45a0b84a6e383b1a237e74c} dryness in cake achieved after second step
  • Effective in all seasons including monsoons
  • Dried cake similar to dried mud
  • Separation efficiency >95{a4503f35f1adc3483e439b6462ef5853fd64d4b5b45a0b84a6e383b1a237e74c}
  • Maximum weight reduction in sludge
  • Elimination of sludge drying beds.
  • Low poly electrolyte consumption
    • No Noise
    • No Maintenance cost
    • No Moving parts
    • No power consumption
    • No foundations
  • Clean and easy handling of sludge
    • No spillage
    • No odour
    • No flies/insects
  • Man-hour requirement is minimal
  • Suitable for dewatering of chemical, sewage, biological and mixed sludge in small ETP/STP plants.



The proposed system features sludge dewatering and flocculationsystem. It consists of Poly preparation tank, ‘poly-sludge’ mixing tankwhich is also called as Flocculator, poly dosing pump and “Sludge Catch” sludge dewatering equipment.

First Polyelectrolyte solution is prepared by mixing polyelectrolyte(powder form) with water in Poly preparation tank to get a solution of 0.1{a4503f35f1adc3483e439b6462ef5853fd64d4b5b45a0b84a6e383b1a237e74c}concentration and then it is pumped through poly dosing pump toFlocculator. Sludge from the sludge-settling tankis also fed to the Flocculator using the sludge feed pumps of capacity 1 m3/hr, with facility for flow adjustment. In theFlocculator the sludge and the poly is mixed continuously with polysolution about three minutes of residence time.Poly dosing is adjusted to achieve formation of big and strong flocks.The flocculated sludge is fed to Sludge Catch Dewatering unit by gravity continuously. The feeding is stopped manually once the bags are filled with sludge in approximately 2 to 3 hrs and is kept standing for another 4 to 5 hrsfor draining of any further free water. The time cycles depends entirely on the quality of sludge and the quality of flocculation.Filtrate generated is collected in the bottom tray of Sludge Catch and led out from the bottom of the unit through outlet nozzle. This filtrate is to be led back to the equalization tank of the ETP by gravity or other suitable system. Sludge collected in bags has to be removed manually, first the mouth of the bag is tied using the tie wires and wire twister provided and then removed using the trolley provided, stacked / stored at suitable location for approximately 10 to 15 days for further dewatering through natural evaporation.After that the dried out sludge is removed from the bag and is sent forfurther disposal. Bags can be washed and reused for dewatering of sludge.New bag are installed and the unit restarted for dewatering of the next batch of sludge.