The Kaldnes 1 plant at Fornham Water Recycling Centre is one of two tertiary treatment units on site using the Kaldnes aeration process. 

Kaldnes 1 has recently been upgraded by the Energy Team. Three old, inefficient and unreliable blowers that used to deliver air to the Kaldnes process have now been replaced by modern, efficient rotary lobe blowers. 

Working with Air Technology, it was identified that combining the replacement of these blowers with an upgrade to ammonia control would make significant savings. Since implementation the energy consumption of the plant has more than halved. 

 “The new blowers and control system have vastly improved the resilience of the plant – as well as saving energy, the system can now respond much more quickly to changes in load, meaning less risk to compliance” Ed Smith, Energy Optimisation Engineer 

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On completion one blower has been running for most of the time with the assist blower starting on high demand. With the three old blowers running the power was 81kW. This has fallen to 40kW in ammonia control. 

The new blowers were also installed within ventilated acoustic enclosures, meaning that the noise levels outside the blower house are much lower than they were before. This also enabled natural ventilation to be used which saved on the installation and future operating costs compared to installing forced ventilation. 

A further benefit of this scheme is that the new blowers can deliver more air at higher pressures than the old ones, meaning that if load goes up in the future the treatment process will be equipped to deal with it. 

The work has been such a success that a similar scheme is planned for the second Kaldnes Plant. 

Aeration Energy Efficiency

‍What can be done  

• Better response to loading – ammonia control
• Blower efficiencies – correct sizing and VSD application
• Fine bubble diffusion application
• Rotor immersion depth adjustment
• Instrument maintenance – DO and ammonia probes