Dolphin Centrifuge

Wastewater Centrifuge | Sludge Dewatering & Thickening

Alfa Laval NX-418 Decanter for Wastewater Sludge Thickening
Alfa Laval NX-418 Decanter for Wastewater Sludge Thickening

Table Of Contents

Types of Wastewater

Wastewater is a generic term for water with solid or liquid contaminants. For example, municipal wastewater has organic sludge, and industrial wastewater carries industrial or inorganic sludge, etc.

Generation in large volumes is the other aspect of wastewater; therefore, the separation equipment must process large amounts of contaminated fluid.

Wastewater from the sources, as mentioned earlier, contains bulk sludge, which is easier to separate. On the other hand, wastewater from mines and oilfield drilling operations contains fine, suspended solids requiring smaller mesh filtration or higher g-force centrifuges.

We also have industrial effluent water, which contains oil in addition to the solids or sludge. This application may need two different centrifuges to separate the sludge and the oil from the de-sludged water.

Separation Technologies

Filtration is not an option for this application, given the type and volume of wastewater that needs to be purified. Other separation technologies, such as belts and filter presses, have limited uses in wastewater separation duties. Again, these technologies have drawbacks, including labor and equipment reliability issues that limit their widespread use in wastewater treatment plants.

Mechanical separation using a wastewater centrifuge has many advantages for continuously processing large quantities of wastewater. As with all technologies, centrifuges also have some drawbacks highlighted below.

Sharples P3000 Wastewater Decanter
Sharples P3000 - 40 GPM - Wastewater Decanter


A wastewater centrifuge is a separation machine that utilizes a centrifugal force of 3,100 Gs to separate the wastewater from sludge. The sludge accumulates on the bowl periphery, and the internal auger scrapes towards the sludge discharge ports. The water flows out through the bowl's liquid outlet at the opposite end.

Dewatering Centrifuge Animation
Dewatering Centrifuge Animation


Three types of centrifuges apply to wastewater depending on the type and amount of sludge. The following section describes these broad categories.

Sludge Thickening or Dewatering Type

Alfa Laval NX-314 Decanter Centrifuge
Alfa Laval NX-314 Decanter Centrifuge

A sludge dewatering or sludge thickening centrifuge is a decanter-type horizontal de-sludger that can remove water from slurries to thicken the sludge. In other words, a heavy-duty industrial centrifuge dewaters and concentrates (thickens) the sludge, also known as a sludge thickening machine. These machines are available in different sizes to continuously process large quantities of sludge-laden water.

Livestock farm manure, municipal sewage, car washes, and oilfield drilling mud produces wastewater with high sludge content of up to 50%. The primary objective of such applications is to reduce the sludge volume to minimize handling and disposal costs. The recovered water is often clean enough to be reused or discharged with minimal environmental impact.

Clarifying Centrifuge for Mining Effluent

A wastewater clarifier centrifuge is a disc-stack type, a high-speed, self-cleaning separator that produces very high centrifugal forces that can separate micron-level suspended particles. The particles are pushed toward the bowl wall and automatically purged during the cleaning cycle. The cleared centrate discharges the bowl continuously through a centrally located outlet port.

Alfa Laval WSPX-303 Concentrator Centrifuge
Alfa Laval WSPX-303 Wastewater Concentrator Centrifuge

Wastewater from mining applications is one such example. This stream contains minute silt and clay particles that are difficult to separate with a wastewater decanter. A high-speed disc centrifuge has sufficient g-force to pull out these particles and clarify the water.

Separator for Industrial Oily Wastewater

Industrial wastewater often carries oil in addition to sludge. This oily water is challenging because it cannot be disposed of in standard drains. A three-phase industrial centrifuge separates the oil from the water, making it disposable.

Industrial cleaning fluid containing shop-floor sludge and oil from the manufacturing run-off is ideal for separation with a liquid-liquid-solid separator.

Alfa Laval Decanter Centrifuge for Vegetable Processing Wastewater
Alfa Laval Decanter - Onion Processing Wastewater


Centrifuge offers many benefits compared to other dewatering and separation technologies. A brief description of some of the advantages follows.

Reduced Transportation and Disposal Expenses

Centrifuges produce dry sludge cake, which significantly reduces transportation costs (up to 50%). Dry sludge also reduces disposal costs because the disposal volume is a fraction of the wet sludge.

Equipment Durability and Longevity

Industrial decanters are heavy-duty machines that have long service lives. Their material of construction (Stainless Steel) provides corrosion resistance in corrosive processing applications.

These centrifuges have superior erosion protection in critical areas for enhanced wear protection. It is not uncommon for these dewatering machines to operate for decades without the need for replacement or even significant rebuilds.

Low Operating Expense

Unlike belt and filter presses, centrifuges do not use filter media, which significantly benefits these machines’ users. Also, this eliminates the labor cost related to media replacement.

The only operational expense associated with centrifuges is maintenance. The only parts that need occasional replacement are the bearings because a decanter has fewer moving parts than filter presses.

Minimized Operator Requirements

Most sludge-thickening and dewatering centrifuges are fully automatic. The control systems have built-in sensors with self-correcting features to allow operator-free processing.

Other methods mentioned above need manual service to replace media or perform other periodic functions.

Compact Size for Processing Capacity

Centrifuges are compact when compared to other dewatering equipment. For equivalent capacity, a decanter footprint is often a fraction of other comparable machines. This small size makes them a viable option for wastewater de-sludging in confined areas in treatment plants.

The centrifuge equipment’s compact size means that its location can be changed or moved to the worksite for ease of use and flexibility.

Specifications and Sizing

Centrifuge specifications and sizing depend highly on the manufacturer and the customer’s capacity throughput requirements. Listed below are some specific technical details and sizes of the commonly used dewatering separators from Alfa Laval.

Dewatering Centrifuge

ManufacturerAlfa Laval Decanter
Rated Capacity170 GPM80 GPM
Capacity on Wastewater with 5% Sludge100 GPM40 GPM
Capacity on Wastewater with 10% Sludge60 GPM25 GPM
Motor Power20 ~ 25 HP10 ~ 15 HP
Weight4,000 Lbs2,500 Lbs
Size / Dimensions3′ x 10′ x 4′ (H)3′ x 8′ x 4′ (H)
Material of Construction (MOC)316L Stainless Steel 316L Stainless Steel
Wear Protection – AugerTungsten Carbide Hard Surfaced AugerTungsten Carbide Hard Surfaced Auger
Wear Protection – Sludge PortsStellite BushingsStellite Bushings
Wear Protection – Inlet Feed ZoneHard Surface or Stellite InsertHard Surface or Stellite Insert

Wastewater Centrifuge

Alfa Laval WHPX-513 Centrifuge for Waste Water Clarification
Alfa Laval WHPX-513 Centrifuge for Waste Water Clarification
DMPX-028 Self-Cleaning Disc Stack Centrifuge for WasteWater
DMPX-028 Self-Cleaning Disc Stack Centrifuge for WasteWater
ManufacturerAlfa Laval Separator
TypeHi-Speed; Disc-Stack; Self-Cleaning
EfficiencySolids Particles down to 0.5 µ
Rated Capacity100 GPM30 GPM
Capacity with 5% Sludge (Max.)80 GPM12 GPM
Motor Power15 HP10 HP
Skid Weight4,000 Lbs3,500 Lbs
Size / Dimensions6′ x 7′ x 7′ (H)4′ x 5′ x 6′ (H)
Bowl Material of Construction (MOC)316L SS w/ Some Red Metal Parts
Disc Stack Configurations2-Phase or 3-Phase
Control SystemFully Automatic PLC & Touchscreen


Dolphin Centrifuge has supplied industrial decanters and disc-stack clarifiers for a wide range of wastewater applications. Some of these applications are listed below.

Disc Stack, Self-Cleaning Centrifuge for Wastewater Clarification at 80 GPM.
Disc Stack, Self-Cleaning Centrifuge for Wastewater Clarification at 80 GPM.
Sludge Thickener for Food Industry 40 GPM @ 15% Solids
Sludge Thickener for Food Industry 40 GPM @ 15% Solids

Wastewater Centrifuge Models for Sale

Dolphin Centrifuge carries a range of Alfa Laval wastewater centrifuges in stock. The following are the various models available for the three types of wastewater centrifuges with additional options.

Alfa Laval WSPX-307 Water Based Coolant Centrifuge
Alfa Laval WSPX-307 Waste-Water Centrifuge

Dewatering Decanter Centrifuges (High Sludge Content)

ModelCapacityOptions Available
Alfa Laval NX 418B-31G20 to 100 GPMFeed Pump w/ VFD Control & Torque Lock
Fluid Tank w/ Level Sensor & Pump
Sludge Auger w/ Motor & Gear Reducer
Bearing Temp. Monitoring System
Automatic Back-Drive Control System
Alfa Laval NX 314 B-31G3 to 40 GPM
Sharples P 340020 to 100 GPM
Sharples P 30003 to 40 GPM

Clarifier Disc Stack Centrifuge (Low Sludge Content) - Wastewater With Oil

ModelCapacityOptional Available
Alfa Laval MOPX 213
3-Phase Centrifuge
Up to 80 GPMFeed Pump w/ VFD Control
Sludge Tank w/ Sludge Pump
Clean Fluid Tank w/ Return Pump
Pre & Post Duplex Filters
Flow-Meter w/ Auto Pump Control
Alfa Laval WSPX 307
3-Phase Centrifuge
Up to 15 GPM

To get more details email us or call us at (248) 522-2573

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