Sludge is a byproduct of a wide range of industrial applications, from power generation to oil refining to drinking water and wastewater treatment. Due to its high liquid content, it is difficult and, consequently, expensive to store and transport for disposal in an unprocessed form. That’s why many industrial facilities invest in dewatering equipment, which is used to separate the sludge’s solid and liquid components to facilitate disposal operations. 

There are many sludge dewatering methods, all of which reduce the volume and weight of the sludge to make it easier to handle and transport. Three of the most commonly used involve employing a centrifuge, a plate and frame filter press, or a belt filter press. Each piece of equipment offers distinct advantages that make it suitable for different dewatering applications. Below, we provide an overview of these three sludge dewatering systems to help readers select the right one for their needs. 

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Centrifuges operate under the principle of buoyancy. They use high rotational speeds—i.e., they spin—to separate components by density. Components with higher densities (e.g., sludge solids) fall to the bottom, while components with lower densities (e.g., sludge liquids) rise to the top. 

The primary benefit of centrifugal dewatering operations is processing speed. They quickly produce between 25% and 35% solids by weight. They are generally used in dewatering applications where the main priority is the recovery oil rather than the quality of the solids. However, they do come with their share of faults. Centrifuges are high energy, not easy to operate on/off, and are difficult to maintain.

Plate and Frame Filter Press

Plate and frame filter presses separate liquids from solids using recessed-chamber filter plates. The filter plates combine to form a chamber, which pressurizes the sludge. The liquids are squeezed through the filter cloth that lines the chamber while the solids remain on the surface of the filter cloth. The entire process takes 4 hours for each batch.

The main benefits are that the solids are formed as stackable cakes, which makes them cost-effective to transport and the equipment does not require any special license to operate. 

Belt Filter Press

Belt filter presses follow a four-stage dewatering process. The four stages are: 1) pretreatment, 2) gravity dewatering, 3) pre-pressure dewatering in the wedge zone, and 4) press dewatering.

The key benefit of belt filter press dewatering operations is high volume capacity. The continual action of the dewatering process is highly effective for processing high volumes of sludge. However, the quality of the filter cake is lower than that of filter cake produced by other methods (between 11% to 20% solids by weight). 

An infographic that explains various sludge dewatering methods

Learn More About Sludge Dewatering From the Experts at ELODE

Sludge dewatering is an important process in many industries. By separating the liquid and solid components of sludge, it improves the cost-effectiveness of disposal operations. 

Want to learn more about sludge dewatering and the various methods available? Ask the experts at ELODE! We supply second-stage dewatering systems designed to further improve the dryness and reduce the weight of sludge, which can result in significant sludge transportation, storage, and disposal cost savings. Our dewatering experience can help us answer or address any questions or concerns you may have about centrifuges, plate and frame filter presses, belt filter presses, or other dewatering systems. Additionally, we can assist you in selecting the right solution for your sludge dewatering needs. 

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