Diffuser system cuts wastewater treatment costs

Many Australian councils face the three-pronged challenge of treating the growing amounts of wastewater caused by population growth, managing the cost of this treatment and meeting and complying with new and stringent discharge limits. Rockhampton Regional Council is one such council.

The South Rockhampton Sewage Treatment Plant currently serves a population of more than 19,000 people, which is no mean feat — especially given that the price of electricity in Queensland rose more than 20% in July 2013 and that the plant must keep under the effluent limit of 5–10 mg/L for total nitrogen.

However, thanks to an upgrade of the treatment plant — which includes using a diffuser system said to be one of the most efficient in the world — the Rockhampton Regional Council has achieved a total nitrogen limit as low as 3.1 mg/L while aiming to reduce electricity costs by up to 20%.

“More than half of the energy used in a treatment plant such as ours is consumed in the biological/aeration process,” said Cr Greg Belz of Rockhampton Regional Council. “This is why we have upgraded the plant by retrofitting it with the highly efficient aeration system of AEROSTRIP diffusers.”

AEROSTRIP diffusers are used to supply oxygen in biological reactors for the treatment of municipal and industrial wastewaters. With their tiny 1 mm bubbles and perforated polyurethane membrane, they have good efficiency and longevity. The diffusers were installed by Hydroflux HUBER.

“AEROSTRIPS are easy to retrofit into existing sites,” said Hydroflux HUBER Director Luis Bastos. “What makes them particularly popular is that, as a result of the superior materials used in their construction, they outlast all other diffuser technologies on the market.

“The main benefits of the AEROSTRIP diffusers are the significant power savings they achieve by the high oxygen transfer rate 4–5 kg O₂/kW and the robustness of the membrane, which has a life of greater than 12 years. All of this is without fouling or loss of pressure.”

“We chose Hydroflux HUBER to install 80 of these four-metre AEROSTRIPS not only because they will cut our energy use while reducing our carbon footprint, but also because Hydroflux HUBER provided performance guarantees for the installation,” said Cr Belz.

Since the installation, the site is achieving outstanding effluent quality and energy efficiency. Independent testing verified the oxygen transfer rates guaranteed by Hydroflux HUBER.

“AEROSTRIPS have been installed at over 2000 sites worldwide,” said Bastos. “They have proved particularly popular in Queensland as AEROSTRIPS also deliver cost savings in electricity and by lowering maintenance costs.”

Image caption: AEROSTRIP diffusers in action at South Rockhampton Sewage Treatment Plant providing high-efficiency oxygen transfer and generous mixing.