Wind put to use at Bell Island

The Nelson Regional Sewerage Business Unit (NRSBU) is trialling the use of wind powered mixers in one of its treatment ponds at Bell Island

Being wind powered, the mixers will offer a considerable saving in operating costs. While not yet widely used in our part of the world, two other facilities in Australia have installed this technology and have seen improvements in the efficiency of the treatment ponds as well alongside the energy savings.

In the long term, the mixers have the potential to reduce the overall level of sludge in the ponds, reducing the need for desludging them. This is a process that usually needs to be carried out every 20 – 25 years when using conventional management methods.

Currently the system is only installed in one treatment pond, which will allow staff to easily measure its effectiveness in comparison to the other ponds.

If the new technology works as expected the potential benefits could include:

• Extending the useful life of the treatment pond

• Avoiding undertaking an environmental analysis and obtaining consents for sludge disposal;

• Improving the quality of the effluent discharged from the WWTP;

• Significant cost savings by deferring conventional sludge removal.

Gurney Environmental, the company that has provided the new equipment, has done so at a 50% investment until its effectiveness is demonstrated. If the NRSBU does achieve the expected improvements, it is obliged to pay the company in full for the equipment and may consider installing it throughout the treatment plant.