Pilot 3: Næstved, Denmark

The project tests nanobubbles as a new solution for wastewater treatment, particularly in cases of high organic load or variable demand.

Pilot focus:

Nanobubble aeration efficiency tests.

Type of pilot measure:

Pilot-scale testing of nanobubble aeration.

Location:

Næstved, Denmark

Site:

Næstved Wastewater Treatment Plant

Applied solution:

Nanobubble generator as the sole aeration method for biological wastewater treatment.

Pilot setup:

Three IBC tanks, each with a maximum capacity of 1 m³.

Utilisation:

Testing oxygen transfer efficiency and biological wastewater treatment performance.

Responsible:

Envafors

About the pilot:

A pilot-scale wastewater treatment plant was installed at Næstved WWTP, Denmark, to test whether nanobubble technology could provide aeration for biological wastewater treatment. The experimental system consisted of three tanks for raw wastewater, biological treatment and treated wastewater. The tests were intended to assess the technology before potential full-scale implementation at Vallensved WWTP.

The tests demonstrated efficient oxygen transfer and showed that nanobubbles could support the removal of nitrogen and chemical oxygen demand (COD). However, the tested system required considerable energy for water pumping and partially disrupted activated-sludge flocs, increasingsuspended solids in the treated effluent. Because of these limitations, the technology was not implemented at fullscale as originally planned. Further tests with an alternative nanobubble generator – a rotating disk membrane – showed lower energy consumption and less disruption of activated sludge, indicating potential for the technology after further optimisation.

More information:

Morten Lykkegaard Christensen
Associate Professor, Head of Section
Section of Bioresources and Process Engineering
Aalborg University
E-mail: [email protected]

Find the pilot sheet here (PDF).

Read more about the project from the report “Technical preparation for wastewater treatment investments at BSR tourist destinations”.

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