High Temperature Resistant Saline-Alkali Resistant Screw Sludge Dewatering Machine

I. Sludge dehydrator introduction

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Screw press sludge dewatering machine is an efficient and reliable solution to sludge water management and wastewater treatment. It utilizes a screw mechanism to transport and compress sludge, separating the water from the solid materials. The dewatered sludge cake is with reduced moisture content and volume, making it easier to handle and dispose of.

It adopts the screw extrusion principle. The rotation of the screw shaft produces a great internal pressure under the blocking action of the backpressure plate while pushing the sludge transportation so that the volume is continuously reduced, and the purpose of dewatering is finally achieved.

Discover the most efficient sludge dewatering machine designed to separate solid and liquid components of sludge. Reduce disposal costs, …

II. Sludge dehydrator description

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Screw press sludge dewatering machine is an efficient and reliable solution to sludge water management and wastewater treatment. It utilizes a screw mechanism to transport and compress sludge, separating the water from the solid materials. The dewatered sludge cake is with reduced moisture content and volume, making it easier to handle and dispose of. Dagyee is a trusted manufacturer of sludge dewatering screw press, providing customization options to meet specific demands. Our machine also serves wastewater treatment, food proccessing industry, etc. 

III. Sludge dehydrator process

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Clog-free self-cleaning mechanism

The heart of the machine is a cylinder that acts as a filter element. It consists of alternating layers of fixed rings and moving rings with a gap in between. Two screws running through the cylinder transfer and compact the sludge through the cylinder, squeezing out the water.

An external driveshaft ensures the constant movement of the rings, creates an elegant and sophisticated self-cleaning function. At the same time, the precise guidance of the moving rings prevents their contact with the surface of the screws. This friction-less design greatly extends the lifetime of consumables. All while maintaining the typical screw press benefits such as ultra low energy and rinsing water consumption compared to alternatives.

Applicable for practically all sludge types – also highly fibrous or inorganic

The two screws rotate into each other, breaking up the solids while transferring and compacting them towards the outlet. This makes the machine close to impossible to block, even with highly fibrous or inorganic sludges that would be fatal for common screw presses and other dewatering machines.

IV. Sludge dehydrator overall composition

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The dehydrator is mainly composed of sludge premix module, concentration and dewatering module and electric control system.

The main body of the screw press dehydrator is a filter device which is superimposed by a plurality of fixed rings and floating rings, and the screw shaft runs through it. The anterior segment is concentrated and the posterior segment is dehydrated. Sludge concentration and dewatering are done in one cylinder.

The screw press, with conical screw shaft and cylindrical screen, consists of three treatment zones: an inlet and drive zone, a three-part thickening and dewatering zone and a press zone with a pneumatic counterpressure cone. Cost-effective sludge dewatering with independent sludge treatment.

In the first part of the thickening and dewatering zone, the supernatant is quickly removed by a feed pump through a large free filter surface at low primary pressure. A pressure probe in the feed zone controls the primary pressure, thus ensuring consistent filtrate quality.

In the second part of the screen, the volume of material between the screw threads is reduced by means of a conical screw and the sludge is pressed against the inner surface of the screen, thus dewatering the sludge and decreasing the cake thickness. The screen aperture in this screen section is much smaller.

In the third part of the screen, the remaining water is pressed out of the sludge with minimum cake thickness by a pneumatic counterpressure cone at the press-out. The dewatered sludge is pushed by a screw conveyor over the pressure cone into the discharge chamber. The residence time of the sludge in the screw press as well as the filtering time can be adjusted by adjusting the speed of the screw shaft to meet individual requirements.

The initial section of dewatering drum is the thickening Zone, where the solid-liquid separating process takes place and where the filtrate will also be discharged. The pitch of the screw and the gap between the rings decrease at the end of dewatering drum, hence increasing its internal pressure, end Plate further increases the pressure, so as to discharge dry sludge cake.

V. Sludge dehydrator complete practical operation steps

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The operation of a Multi-disc Screw Press follows these basic steps:

Sludge Conditioning

Polymer is mixed with the incoming sludge to agglomerate the solid particles, forming larger flocs. This increases filtration efficiency.

Sludge Feeding

The conditioned sludge is fed into the dewatering drum.

Thickening and Dewatering

The drum consists of a screw shaft that rotates slowly. Surrounding this screw are alternating fixed and moving rings. As the screw rotates, it transports the sludge toward the outlet. During this movement: Water is drained through the narrow gaps between the discs. Pressure increases as the pitch of the screw tightens and the volume decreases, squeezing more water out of the sludge.

Cake Discharge

The dewatered sludge (now a semi-solid cake) is pushed out from the end of the screw shaft for disposal or reuse.

Sludge is first flow into the Control Tank and then flows down into the Flocculation Tank, Where polymer coagulant is added. From there, the flocculated sludge overflows into the dewatering drum where it is filtered and compressed. The entire operation sequence, including sludge feed control, polymer makeup, dosing and sludge cake discharge are controlled by the built-in timer and sensors of the PLC.

The sludge is delivered to the metering tank through the sludge pump, and then the sludge flows into the flocculation mixing tank. The excess sludge flows back to the sludge tank from the overflow pipe. Inject polymer flocculants into the flocculation mixing tank, alum floc formed after stirring, and then enters into a dewatering section of a screw press after gravity concentration (pre-treatment) section. Flocculation and dewatering are carried out in sequence, so that we have a three-stage separation process: flocculation, dewatering and concentrate recovery.

The sludge enters the dewatering machine and the sludge moves towards the sludge cake outlet under pressure from the helical screw blades. Since the pitch becomes narrower towards the outlet of the sludge cake, the sludge bears heavier pressure and begins to dewater. Water comes out from the space between fixed and moving rings while dry solids exits from the outlet.

In the actual working process, the sludge is pumped to the metering tank by an external conveying pump. The sludge after distribution further flows into the flocculation tank, reacts with the flocculant fully under the stirring of the agitator to produce stable alum flocs, and then enters the dewatering screw through the upper part of the flocculation tank. In the dehydrated body, alum flowers concentrate in the concentrated section by gravity and advance to the dehydrated section at the same time. In the process of propulsion, with the filter clearance and pitch gradually reduced, and the back pressure plate blocking effect. During the spiral rotation, the floating ring and the fixed ring will form a dislocation movement, and the water will be discharged from the gap between the floating ring and the fixed ring. It replaces the traditional filter cloth filtering method with a unique and subtle filter pattern.

VI. Sludge dehydrator model

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VII.Sludge dehydrator advantages

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(1) Adopt independent research and development technology

The main shaft adopts the self-developed technology of taper shaft and variable pitch. The sludge increases the axial and radial bidirectional pressure during the operation of the screw shaft, which improves the dehydration rate and work efficiency. [Read also: Screw Press Sludge Dewatering: An Effective Solution for Wastewater Treatment.

(2) Laser cutting and leveling processing technology

Using laser cutting and leveling technology processing technology, the flatness of the laminated sheet increases the dewatering rate of the equipment, and the sludge cake is dried to clear the water effect, and the stacked screw sludge dewatering machine will not leak mud, run mud, and appear thin mud soup. 

(3) Long service life 

The body of the sludge dewatering machine is made of 304 stainless steel, which is corrosion-resistant and wear-resistant.

(4) Automated procedures, saving water and electricity, and reducing project costs

Due to the use of low-speed screw extrusion technology, the power consumption is very low. At the same time, it is equipped with an automatic spray system, which avoids clogging and does not require a lot of water to rinse.

VIII. Sludge dehydrator key features

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Simple operation and maintenance

Through a variety of induction control can realize all-weather automatic unattended operation, less routine maintenance items.

Compact design, saving space

Screw dewatering water, flocculation mixing tank, electric control cabinet press adopts trinity design, easy installation, small footprint.

Energy saving, water saving, low noise, low vibration

The core component screw shaft speed is 2~4 RPM, so the power consumption is very low. Its self-cleaning structure can prevent the filter slit clogging, can save a lot of cleaning water. There is almost no noise and vibration when rotating at low speed, ensuring a comfortable and quiet working environment.

Strong anti-sludge ability, easy to separate and not blocked

Self-cleaning structure of screw press dehydrator, not easy to cause filter seam blockage, even if the sludge can be easily handled. Kuosi also has an oil sludge treatment system to recover valuable substances from the sludge and reduce waste emissions. It should be noted that the sludge needs to be flocculated in the mixing tank and then passed through the overflow port into the dewatering water. Therefore, the sludge entering the screw press dehydrator must have certain fluidity.

IX. Sludge dehydrator applications

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Dewatering screw press is widely used across various industries, with applications in fruit and vegetable juicing, plant dewatering, processing spent grains. It plays a vital role in managing agricultural waste, including grass, stalks, and coconut shells, as well as fruit and vegetable waste and food waste. Additionally, it effectively handles wastewater and slurry, excelling in managing animal manure. This versatile machine also dewaters materials like paper pulp and sludge, making it a key component in sustainable waste management practices.

Screw press dewatering machine is widely used in fruit and vegetable juicing, agricultural waste dewatering, distiller’s grains dewatering, crushing and dewatering of fruit waste and vegetable waste, decomposition of food waste, extrusion dewatering of domestic waste, solid-liquid separation of animal feces, dewatering of pulp, sawdust, and sludge.

The versatility of the Sludge Dewatering Machine allows it to handle a wide variety of sludge types.

It is suitable for:

STP (Municipal Sewage sludge)

Dying Plant

ETP (Primary & Secondary)

Slaughter House

Oil Refinery

Tannery Sludge

Sludge from DAF

Solid Fuel Boiler Scrubber Water

Whether dealing with oily sludge, organic sludge, or fibrous sludge, it can adapt and deliver consistent performance.

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