Low Temperature Resistant Heavy Duty Chemical Wastewater 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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DAGYEE is a leading industrial manufacturing company that has been providing high-quality Dewatering Sludge Machines since its establishment in 2019. Over the years, the company has expanded its product line to include other products such as  Dissolved Air Floatation Unit - (DAF) and polymer preparation unit in addition to earlier product range like  Oil Skimmer.

III. Sludge dehydrator process

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A screw press (SP) provides sludge dewatering by conveying the sludge along the inside of a permeable cylinder. It is based on a slowly-rotating (~5 RPM) Archimedean screw within a cylindrical screen (otherwise termed drum filter/screen or basket). It is normally inclined by ~20° to the horizontal to assist with the draining of water into the sump. The screen generally has an aperture rating below 0.5 mm and is based on wedge-wire or occasionally perforated metal.

The screens are less susceptible to clogging than the filter media used for other thickening and dewatering processes. Consequently, spray-cleaning is applied only intermittently for around 2−4% of the operating time.

As with all thickening and dewatering processes, the product solids (or cake) content is dependent on the feedwater sludge quality. The cake solids content has been shown to be inversely proportional to the volatile solids (VS) of the feed sludge.

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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The premix module and dewatering water of screw press dehydrator are the parts in contact with sludge, according to the supplier’s standard, sludge condition, and different requirements of equipment users. Usually these parts are made of stainless steel. The conventional material on the market is stainless steel 304, followed by stainless steel 316. Better materials have better corrosion resistance, but they also mean higher prices.

There are multiple washers between the floating ring and the disk support screw, which can prevent the floating ring from generating too much friction with the lead screw in the reciprocating movement for a long time, thus extending the working time of the floating ring. Gasket material can be stainless steel can also be plastic, material difference will greatly affect the price. Depending on the size of the device, there are usually hundreds or thousands of gaskets installed in a single screw pressure machine.

The power of up and down movement of the floating ring in the process of dehydration comes from the extrusion of the inner screw on the floating ring, so it is necessary to protect the edge of the spiral blade from wear. Whether the screw blade is protected by wear-resistant coating will affect the service life of the screw. Some manufacturers connect all the floating rings together with independent lead screws, and provide power with a power supply different from the main lead screw drive device to prevent the floating ring from contacting the spiral blade, so as to protect the lead screw and floating ring.
In the choice of motor, reducer and electrical components, manufacturers and users have different preferences for different brands and places of origin. Usually manufacturers will provide solutions according to their own standard configuration, but can also provide customized solutions according to user requirements.

The electric control cabinet centralized all the operation control of screw press dehydrator. According to the working site temperature, humidity, sunshine and other conditions, the user can choose carbon steel spray or stainless steel control cabinet. For more automated control, users can also ask manufacturers to design PLC control and display designs to detect health.

VIII. Sludge dehydrator key features

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Wastewater Treatment Plants and SewerSystems

DAGYEE is expert in providing superior products,machines and solutions for wastewater treatmentplants and sewer networks.

Industrial Companies

DAGYEE is your experienced, reliable partner forvarious industrial branches and offers a full range ofprocesses,solutions and machines for treatment ofwastewater sludge and waste.

Drinking Water Suppliers

DAGYEE has products and solutions for the treat.ment, storage and distribution of drinking water.

Residentialand Commercialreal Estate

DAGYEE has developed solutions for heating andcooling with wastewater as a regenerative energysource -an important contribution to sustainablebuilding technology.

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:

Industrial wastewater coagulation sedimentation sludge

Urban sewage treatment surplus sludge

Community sewage sludge

Adding chemicals to agglomerate sludge in the water purification plant

Water and fertilizer treatment of surplus sludge

Solid-liquid separation in the factory manufacturing process

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

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