Heat exchangers – energy recovery sludge

Our heat exchangers are recovering heat from sludge, manure, wastewater and highly viscous liquids. Between 10 and 55 °C of heat is recovered, depending on the source. This recovered heat can be used to preheat process waters and all kinds of incloming flows. A good example is the preheating in digestion processes in biogas plants.

Heat exchangers for sludge/water and sludge/sludge applications

Heat exchangers for energy recovery : high efficiency and low costs with simple and compact units

Läckeby heat exchangers for energy recovery from sludge: unique patented design, reduced footprint (stackable system, cost saving equipment. Our heat exchangers are very compact units, insensitive to clogging, almost maintenance free, for highly viscous substances, such as wastewater treatment sludge, digested sludge, sludge from biogas plants. In short:

Technical features

  • specifically designed for sludge
  • patented turning chambers
  • high heat transfer
  • large throughput area
  • minimal pressure loss

Very high heat transfer with a minimal footprint:

  • Homogeneous sludge temperature through excellent mixing in the turning chambers
  • Insulated housing to prevent energy loss
  • Highly efficient and compact design, minimal space required
  • Extremely maintenance friendly, insensitive to clogging
  • Hinged turning chamber covers for quick inspection


  • compact (stackable) and easy to install unit
  • easy inspection and maintenance
  • no clogging
  • for highly viscous substances

Any questions, please let us know. Don’t hesitate to get in touch.

What is a sludge heat exchanger?

Our sludge heat exchanger are specially designed for use on highly viscuous sustances, such as sludge. These heat exchangers are designed to cope with these difficult liquids: compact units, unsensitive to clogging, easy inspection and maintenance, high heat transfer and large throughput area. Two main versions are available: the sludge-water heat exchanger and the sludge-sludge heat exchanger.

Sludge-water heat exchanger

Have a closer look and find out how it works here.


Below is a selection of our heat exchanger realizations worldwide, some by the manufacturer Läckeby Sweden, some by our colleagues abroad, some by Task. We are continuously replenishing our case studies with more detailed descriptions, pictures and films. So please take a peek regularly! Click the pictures below to access the case study files.

Heat Exchanger sludge – energy recovery from highly viscous substances and from compressed hot air

Heat Recovery – the context

As Task Environmental Engineering is building wastewater treatment as well emission and odor treatment plants, we are committed to maintain our environment as clean and healthy as possible. As we all know, there is still plenty of room for improvement. A lot of excess heat is created in wastewater treatment plants and in biogas production. Why shouldn’t we use and recover this excess heat? Our durable sludge/ sludge, sludge/water and air/water heat exchangers are designed to recover a majority of the excess heat, greatly increasing operational efficiency and reducing production costs. heat recovery for circulare energy use Task is your contact for the Läckeby (Swedish quality product) range in the Benelux market (Belgium, Grand Duchy of Luxembourg and the Netherlands). These excellent Läckeby heat exchangers have been installed in waste water treatment and biogas plants for more than 20 years. These compact, high-quality heat exchangers offer a high level of heat recovery, enhanced production efficiency, a long service life and easy maintenance.

Heat Recovery – Energy recovery : the scope

Warm, highly viscous substances

In the digestion process of manure, green crops, wastewater sludge, household and restaurant waste, large amounts of excess heat are generated. This excess heat can be used to pre-heat the digestion substrates or provide domestic hot water. Läckeby offers heat exchangers that can handle viscous low velocity sludges, efficiently transferring heat with minimal risk of clogging.

Sludge applications

  • direct heating or cooling of raw or digested sludge on the feed line
  • heating or cooling of digested sludge by means of digester or pasteurization circulation
  • energy recovery from warm sludge
  • agro-industrial digestion
  • vegetables, fruit and garden waste digesters
  • biogas recovery from waste dumps

Wastewater applications

  • cooling of wastewater in biological wastewater treatment applications
  • energy recovery out of outgoing wastewaters
  • biogas production from urban water purification and industrial wastewater

Green energy from sludge

By connecting two sludge/water units with a water loop, we can recover the already generated heat to pre-heat the incoming sludge, upstream in the process. This water loop based design eliminates the risk of contamination and provides the flexibility to control the process temperatures.

Hot air

The Läckeby air/water heat exchangers were originally developed for a very specific application: to protect the membranes in wastewater treatment plants. But, as a matter of fact, practically all industries generate heat as a by-product of their production process. The Läckeby air/water heat exchangers turn this excess heat or hot process air into profit. Using our heat exchangers in the process, the investment will be rapidly paid back.

Energy recovery from sludge and hot air

Heat recovery is one of the most profitable and environmental friendly investments available. We offer cost effective, solid and modularized heat exchanger solutions, that can be custom designed for perfect fit in your production process.

Heat exchanger types:

Heat exchangers sludge/sludge

Heat exchanger sludge sludge The sludge/sludge heat exchanger draws heat from sanitized or digested sludge and transfers it to the raw sludge by means of a closed water loop system. This design eliminates the risk of contamination. Circular sludge channels ensure a large throughput area, which reduces pressure losses. The patented open turning chambers allow higher temperature transfer by levelling out the sludge temperature profile. This robust and modularized product features high reliability, high heat transfer and low maintenance requirements.

Heat exchangers sludge/water

Heat exchanger sludge water Modular design sludge/water heat exchangers from Läckeby are compact, easy to install and easy maintenance. Circular sludge channels and the patented open turning chamber provide high heat transfer, low pressure losses and minimal risk of clogging. Since the 1990’s more than 400 of Läckeby’s sludge/water and sludge/sludge heat exchanger units have been installed in municipal and industrial plants in more than 20 countries worldwide. The sludge/water heat exchanger in detail :


Heat exchangers air/water

Warmtewisselaar lucht water

The air/water heat exchanger from Läckeby was originally developed to protect and extend the service life of the membranes used in waste water treatment plants. The heat exchanger is designed to effectively reduce the temperature of the air that passes over the aeration membranes. Over the years, we’ve realized that this unique product is perfect for recovering heat from blower-produced air streams as well, perfectly suitable for efficient heating of ventilation air or low pressure hot water systems. Compressed hot air flows freely between a large number of copper loops containing the cooling agent, circulating to recover large amounts of the incoming airstream’s heat. The air/water heat exchanger in detail : 



Task/Läckeby manufactures and installs all the necessary infrastructure to make your heat exchanger installation as efficient as possible. We offer a complete range of shaftless transportation augurs/conveyors, transportation screws, shaftless screw presses and reception units. This is a complete solution from a responsible supplier.

Installation and service

And of course Task/Läckeby are ensuring efficient installation and commissioning of each heat exchanger product. On top of that, we offer complete service and maintenance programs, including monitoring, technical support and upgrading of equipment.

Heat exchanger – gather the heat

The heat exchangers from Läckeby are built to gather the heat. Our robust, high-quality products offer high heat recovery and cost savings in a multitude of applications.

Heating biogas substrates

A proven high performance and very effective application of our sludge/sludge heat exchanger is found in anaerobic digestion facilities and biogas upgrading plants – both for large scale projects and for smaller systems, typically using farm or restaurant waste. The excess heat, produced during digestion and biogas upgrading, can be used to preheat the substrates, speeding up digestion and reducing energy consumption.

Pre-heating hot water systems

Our sludge/water, and air/water heat exchangers are perfect for preheating hot water services. Where can this hot water be used? The obvious application is for internal consumption on site such as wastewater treatment plants, but also for industries using large amounts of hot water, e g laundries. The air/water heat exchangers from Läckeby are very versatile. They heat up water and cool down the airstream. Where? Well, you decide – maybe cost effective air conditioning or central heating?

More information

Task Environmental Engineering is your contact for the Benelux market (Belgium, Grand Duchy of Luxembourg and the Netherlands) for the Läckeby heat exchangers.