Inverell upgrades 30-year-old aeration system

When Inverell Shire Council needed to refurbish and upgrade its aerator tanks, Aquatec Maxcon was selected to tackle the project. The aeration system at the Inverell Sewage Treatment Plant had been in operation for over 30 years, and the three-phase project entailed the building of a new tank, to allow for the two original tanks to be taken offline for refurbishment.

To ensure the upgraded aeration system would operate optimally, the company recommended the installation of its AquaSTAR vertical shaft surface aerator, designed to provide efficient oxygen transfer and optimised mixing rates. It features a folded impeller blade that prevents ragging or fouling, even when used with unscreened wastewater, and requires minimal maintenance.

The AquaSTAR comes standard with safety features, including misters in the motor for temperature control, an oil pressure and oil level switch, and anti-condensation heaters in the motor. The council embraced these safety features as well as the SCADA system and in-built safety alarms.

“These fail-safes will alert the operator to something like critical oil pressure or oil level. This will allow the operator to remotely turn off that infrastructure before it critically fails. These alarms increase the reliability of these assets,” explained Zak Smith, Standard Products & Service Manager, Aquatec Maxcon.

The company also selected Bonfiglioli gearboxes to power the refurbished aerators.

“Quality was a key consideration. The council had some experience with Bonfiglioli solutions, and recommended them for the project,” said Edward O’Brien, Aquatec Maxcon Product Manager. “We were impressed with the customer service and technical expertise we received from Bonfiglioli.”

The Bonfiglioli HDP 90 was selected to power the aerator. This parallel shaft heavy-duty gear unit offers high torque density and highly transmissible power, along with silent and vibration-free operation — and it is robust. It is designed to be easily customised, providing mounting flexibility with a bolt-on flange, and can handle a torque range up to 21,600 Nm.

The HDP series offers Monobloc housing in rigid, spheroidal cast iron, paint coated both internally and externally. If provides universal mounting due to the many machined surfaces. Profiles and dimensions are optimised by FEM analysis for superior structural rigidity and low acoustic emissions, which provides torque range up to 210 kNm. With its ISO 12944-C4 coating, it can withstand the extreme operating environments associated with aerator systems.

“The HDP is designed to deliver optimum performance even in the harshest environments, and is favoured for its low maintenance costs,” said Harry Singh, National Sales Manager, at Bonfiglioli Transmissions Australia.

While the HDP is a heavy-duty gearbox, it proved suitable for the project.

“The motor and gearbox are attached to an impeller, which is supported by a frame which floats on the lagoon. Any change in weight needs to be an engineering consideration for buoyancy and for the depth of the impeller,” Smith said. “Utilising a heavy, sturdy, good-quality gearbox gives you that 30-year equipment life. The market is only just starting to realise this, after a decade of using cheaper, faster impeller aerators that aren’t the best long-term solution.”

O’Brien added, “We’ve found that high speed drives are prone to catastrophic failure. We recommend low speed impellers, designed to deliver a long service life.”

The installation was not without its challenges — including a lack of mechanical install resources. Aquatec Maxcon sent its install crew from Cairns to manage the process. The team also encountered a minor technical issue during assembly.

“It’s difficult to find technical manufacturing and machining services. We found a tremendous company in Boss Engineering, providing some very technical machining. We were thankfully directed to them by the council who had a relationship with the company,” O’Brien said.

Bonfiglioli also stepped up for the project. During the pre-assembly QA check at the Bonfiglioli workshop, the engineers detected an anomaly in the gearboxes.

“These needed to get back to the factory. There’s a tremendous cost involved in removing the gearboxes to get them back to the factory. Bonfiglioli did right by us. They acknowledged the concerns and fixed it. We were impressed by their customer service and honesty,” O’Brien said.

Aquatec Maxcon is preparing for the rollout of the second and then final phase of the project, when the two refurbished aerator systems will be back online.

The company said Inverell will benefit from the operational flexibility of the new installation.

“Because of the increased impeller efficiency and the higher SOTR rate of the new impeller, they can either choose to use less power or increase the treatment quality, as needed. For example, if there’s a holiday and more people are in town, they can turn the aerators up and achieve the same treatment quality as they would have done previously,” Smith said.

“Plus, the smarter feedback on operational alarms means they’ll save money in unnecessary site attendance and reduce the risks of operators having to get onto lagoons. It will reduce the inspection regime and give them peace of mind that everything is running to plan.”

Looking ahead, the Aquatec Maxcon team is planning future projects, having already secured additional orders for this solution.

“There was an extra order for Bonfiglioli and us, on a very short lead time. Bonfiglioli delivered on that too,” Smith said.

Singh said, “We are proud to partner with Aquatec Maxcon and provide customers across Australia with class-leading solutions that ensure their water and wastewater treatment operations are as efficient and cost effective as possible. We look forward to our future projects with the team at Aquatec Maxcon.”

Image caption: Inverell aerator tank upgrade. Image: Supplied.