Heat exchangers WWTP Bath

Heat exchangers

Heat exchanger installation (four units) Wastewater treatment plant Bath – the Netherlands (Zeeland province) – Wolter and Dros for Water Authority Brabantse Delta

Sludge/water heat exchangers. Two heat exchangers are used to recover the energy from sewer sludge, two other heat exchangers to recover the heat from digester sludge coming from the wastewater treatment plant.

For the sewer sludge, two heat exchanger of 550 kW each were used, at a dry solids content of 4 to 8 %, a sludge flow of 20 to 40 m³/h. The incoming sewer sludge temperature is 9 °C, that of the incoming water 85 °C.

For the digester sludge, two heat exchangers with a capacity of 125 kW each are used, at a dry solids content of 4 to 8 % and a sludge flow of 25 m³/h. The temperature of the incoming sludge is 53 °C. Sludge temperature after the heat exchanger: 57 °C. Incoming water temperature: 70 °C.

The entire design is based on the kW demand, being 550 kw in this specific case.

Because of the fluctuating flow levels (spread of 50 %), we’ve chosen a type of heat exchanger able to handle these fluctuations.

The sludge is thoroughly mixed in the turning chambers, assuring a homogeneous sludge temperature.

The Läckeby heat exchangers are designed for a high flow rate, assuring a continuous turbulence of the sludge.

A good insulation of the units makes sure that the heat losses are reduced as much as possible.

These three design principles have led to highly performant heat exchangers, with a compact design and low footprint. The modular system allows to reduce the spacial footprint of the patented Läckeby heat exchangers to the maximum, with stackable units.

Inspection and maintenance are quick and easy (just a few bolt away, with hinged turning chambers for easy access).

The Läckeby heat exchanger sludge/water combines innovative thinking and 40 years of experience in this sector. This unit has been developed to meet special requirements for the heating or cooling of sludge. The unique patented design provides a compact heat exchanger with minimal maintenance needs.

Efficient energy optimization

The Läckeby heat exchanger sludge/water is a specifically designed unit for highly viscuous media. The patented turning chambers enable us to design heat exchangers featuring the highest possible heat transfer ratio, as well as meeting demands for the smallest possible footprint. The compact design and minimal maintenance needs, also ensure that the operating cost for this Läckeby heating or cooling system remains as low as possible. Over the years, the Läckeby heat exchangers will turn out to be an excellent investment.


Modular design: sludge/water heat exchangers from Läckeby are robust, compact, easy to install and maintain and highly reliable. Circular sludge channels ensure that large particles still can get through, but also keep the risk for clogging to a minimum. The innovative design with patented turning chamber assures high energy transfer and low pressure losses. Further on, this robust and modularized product is featuring high reliability, together with low maintenance requirements.

Sludge applications, some examples (non exhaustive list):

  • Direct heating or cooling of raw or digested sludge on the feed line
  • Heating and/or cooling of digested sludge by digester or pasteurization circulation
  • Energy recovery from heated sludge

Wastewater applications, some examples (non exhaustive list):

  • Wastewater cooling in for example biological tanks
  • Energy recovery from outgoing wastewater