Sludge dewatering: achieving the right dryness levels

29 July 2022

Sludge is the outcome that remains after the wastewater treatment process. This waste usually contains pollutants, which means that it must be disposed of instantly. In almost all cases, sludge dewatering is part of the treatment process, as it reduces the volume and mass of the material and makes treatment and transport much easier and faster. Let's look at the possible solutions for sludge dewatering.

Sludge dewatering process

Based on the design of the press plates, there are chamber filter presses and membrane filter presses, which are both excellent for sludge dewatering and can also be used in processes where the slurry is to be recovered. In these machines, the filter plates form the chambers on the surface of which the filter cloth is placed. The sludge enters the structure through the holes connecting the chambers, by using a dosing pump. 

The liquid passes through the filters, which trap larger particles, leaving the solids in the chamber. As the dry matter content of the sludge increases, the permeability of the chambers decreases. When a certain pressure level is reached, automatic loading stops, and as water escapes through the holes and consequently the pressure decreases, the machine starts functioning again. The process ends when the sludge remaining in the chambers has reached a sufficient dry matter content. The waste is discharged at this point and the whole process can restart.

What technologies can be used to carry out sludge dewatering?

Sludge dewatering can be carried out using several technologies. We have collected what you need to know about them.


The advantage of centrifuges is that they can achieve a very dry matter outcome and can handle even larger volumes. However, due to the high cost of the technology itself, these machines could not flood the market. 

Belt filter press

Belt filter presses are often found in residential wastewater treatment plants. These machines are capable of dewatering huge volumes of material and are also capable of operating continuously. However, it is important to know that these are complex structures and therefore require uninterrupted supervision and a lot of washing water to operate.

Chamber filter press

Chamber filter presses are typically used where the aim is to reduce the dry matter content of the sludge as much as possible while reducing its mass. These machines can perform well in the drying process, but their capacity is affected by the chamber volume. For sludge created by the galvanising, painting and engineering industries, chamber filter presses are highly recommended.

Screw press

The screw press can replace belt presses and centrifuges in certain situations. A new technology, the screw press is easy to operate, quiet and requires low-level maintenance.

The press types have different dewatering performances. The efficiency of the screw press and the centrifuge is about the same. The belt filter press has slightly lower efficiency compared to them. Overall, the chamber press has the highest efficiency. The centrifuge has a higher noise level, while the other presses are much quieter during operation. Centrifuges and belt filter presses have more wear parts and a shorter lifetime than screw and chamber presses. 

The sludge dewatering process can therefore be carried out using several technologies. There is no single best solution, and specific circumstances must always be considered.

Makrofilt offers sludge dewatering services to a wide range of industries, including pharmaceuticals, chemicals, brewing, paints, food, galvanising, ceramics and municipal wastewater treatment.

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Makrofilt Szűréstechnikai Kft.
2200 Monor, Péteri út 014/19 hrsz.
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