Dewatering & Separation
What is dewatering & separating?
Dewatering and separation are open-to-atmosphere compaction or non-compaction mechanical processes ideal for handling slurry and sludge-type products and other moisture-containing products. These processes utilize sieve screens to remove solids from liquid-based materials, efficiently separating them into solid and liquid components for further processing or disposal.
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Dewatering and separation equipment
For most requirements.
These machines are optimal for compacting many input materials and delivering high-level dewatering and separation capabilities. Their versatility makes them the most adaptable option within this category of machinery.
These modules offer a cost-effective solution, extracting extra liquid from dry elements discharged by non-compaction equipment. They integrate seamlessly or supplement existing systems.
These units, known for their simplicity and cost-effectiveness, can process various inputs. Static and vibrating versions are available, with the latter being more efficient, yet both operate on the same principles and handle the same input range.
The less familiar approach consists of two variations, each operating on unique principles to handle a broad range of incoming products. Differentiating between internal and external options refers to the drum’s working face, inside or outside, each tailored to specific input products.
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Input products appropriate for dewatering and separation
These input products possess two fundamental characteristics:
Sludge/Slurry Types: These involve solid matter, including sewage and effluents, pulp, pastes, oils, and fats, as well as processed, purified, and recycled items. This category also encompasses manufactured goods that incorporate fruits, vegetables, and products derived from crops and animals.
Liquid with Hard Solid Matter relates to liquids containing solid elements like aggregates and waste stream products.
Dewatering and separating definitions
Although both methods remove the solid portion from the input products, the separating and dewatering processes are easily distinguishable.
Dewatering is frequently employed to thicken, dry, reduce volume, or compact the solid component, and more often than not, the removed liquid is the undesirable component.
Separating has two functions:
- Capturing the solids with the liquid either discarded or recycled for reuse.
- Capturing the liquid element, typically, the solids are discarded.
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Quality of the end product after separating or dewatering
The quality and level of the processed dry and liquid elements are determined by two fundamental concepts for dewatering and separating sludge and liquid products:
- How many solid particles are still present in the liquid component. The size of the sieve screens’ gap generally determines this; the smaller the opening, the fewer particulates are left in the liquid (for clarity, see non-compaction below).
- Any liquid in the solids’ element affects its volume/size, weight, dry matter content, and physical properties.
The intended processing quality not only depends on the above and whether compaction is required, but the actual incoming product, detailed later on this page, will also have some effect.
Non-Compaction
Utilizes gravity
Due to their simplicity, this equipment is typically less expensive than compaction machinery as it relies primarily on gravity and has few mechanics. However, to enhance efficiency for some applications, one or more of the following are fitted: wipers, scrapers, rollers, brushes, vibrators, and even compaction modules.
High throughputs are achieved by exposing incoming products to a substantial sieve screen surface area, making this equipment highly scalable for large applications.
Incoming products typically include low-dry matter, pumpable, wet granular products, slurries, sludges, and dewater at a lower level due to a higher liquid concentration in the solid element.
First Stage of a Two-Stage Process
With no mechanical force, fewer particles smaller than the sieve gap size pass through the sieve screen with the liquid. Instead, they remain with the dry element on the screen surface.
This lack of mechanical force, combined with high throughputs, makes this equipment an ideal first-stage process for efficiently removing the bulk of the liquid before a compaction process. The quality of the process is not compromised; in fact, some applications even see improvements.
SMG provides two alternatives for the second-stage compaction procedure: the Screw Press or our integrated Compaction Module. The latter can be combined with our non-compaction equipment, offering a cost-effective solution for enhancing liquid removal from the dry element.
Compaction
Mechanical force
A mechanical force is applied to compact/squeeze the incoming sludge or liquid-based product that pushes the liquid through the sieve screen.
Due to the nature of this process, the machinery needs to be more robust, which tends to make them higher in cost, but are generally smaller in size than non-compaction equipment.
This mechanical compaction force gives these machines distinct advantages over non-compaction:
- They can be used in almost all process applications for inputs such as pastes with suspended solids, tricky, sticky, viscous slurries, and sludges, along with particular whole and smashed fruits, vegetables, and crops, but with the exception of inputs that have incompressible, hard solids particles, for examples wet granular products.
High levels of dewatering and separation are achievable because:
- Use finer, smaller gap sieve screens that remove significantly more solid particles.
- The dry element has a high dry matter concentration, drastically reducing its volume and turning it into a stackable product.
Compaction or Non-compaction
Whether compaction or non-compaction is suitable for an input product is guided by factors such as its characteristics, required throughput, and the final product’s desired quality. The suitability for compaction varies, with some inputs being compressible and others not. For example, compaction would prove ineffective for input products with incompressible solids but might be suitable for others.
SMG Industries offers a comprehensive range of separation and dewatering solutions, encompassing three distinct technologies: Screw Press & Compaction Modules for compaction and Rundown, & Rotary Screens for non-compaction.
Limitations of dewatering and separation
Dewatering and separation are mechanical processes with natural limitations when eliminating solid particles based on their physical size. Typically, these operations are characterized by medium to high throughput. Attempting to extract microscopic particles using extremely fine sieves can be impractical, as it could significantly diminish throughput to an unusable or unacceptable level.
Below, we outline several solutions to address this, each with links that provide more detailed information.
Because larger solid particles could otherwise overwhelm filtrations’ fine sieve screens, it is employed alone or after a separation or dewatering procedure that removes those larger solid particles.
Coagulants are added to the input product before passing through separation, dewatering or filtration processes.
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