Energy efficiency is the first step on the road to decarbonisation, but how can older wastewater treatment plants cut down power usage without impacting performance?
According to Atlas Copco Low Pressure Specialist, Greg Williams, blowers are responsible for around 70 per cent of all energy used on a wastewater treatment site. However, optimising power consumption is not just about choosing a more efficient device.
“In older plants, blowers are primarily used for aeration in large tanks. These tanks require more air during peak times and less during off-peak periods,” he said.
“The diffused air introduced into the tanks sustains the microorganisms that decompose waste in the bioreactors. Precise aeration is critical, as over- or under-aeration can disrupt the delicate balance required for optimal biological activity.
“This process, combined with the changing demands, results in variable air requirements from the blowers, rather than a fixed flow rate.”
Mr Williams explained that the ability to adapt to this variability is critical to optimising a blower’s energy consumption.
“Atlas Copco’s range of ZS oil-free rotary screw blowers can incorporate a variable speed drive that allows them to adjust the flow range. This ensures that only the required flow is delivered to the tanks during low-demand times, saving energy and costs.”
Silent treatment
Mr Williams said that the Atlas Copco team recently assisted a wastewater treatment plant in New South Wales to overcome similar challenges. He explained that the plant’s existing turbo blowers, which were around 25 years old, no longer met the facility’s diverse flow rate demands.
“The old machines were very noisy and had significant issues with turndown. At night, they had to vent the extra air to the atmosphere because they couldn’t adjust the blowers, leading to noise pollution and wasted energy,” he said.
After a detailed assessment where the company examined the system and simulated new installations to identify the best solution, Mr Williams said that Atlas Copco recommended ZS5VSD Screw Blowers as an ideal replacement.
“[Compared to older machines], the ZS5VSD is about 35 per cent more efficient, and they couldn’t believe how quiet our machines were,” he said.
“Due to the efficiency of our rotary screw technology, we were able to reduce the installed power total significantly. They previously had five 132kW blowers on site and the new package included five 75kW ZS5VSD blowers to do the same job.
“Atlas Copco also undertook all the design and engineering work and collaborated with local contractors to complete the installation. The site team was extremely satisfied with the overall outcome.”
Efficient operator
For Mr Williams, taking a customised approach is non‑negotiable.
“For existing wastewater plants looking to reduce energy, we typically place data loggers on the installed blowers for a full week. The collected data is then input into dedicated Atlas Copco software to simulate our machines within the system,” he said.
“This allows us to demonstrate energy savings and assess the plant’s performance, enabling the customer to see their air usage clearly.”
While Atlas Copco’s line of ZS screw blowers were the correct solution for this site, Mr Williams said that the company offers a range of low-pressure technology to meet every site’s requirements.
“You don’t have to replace your existing machines with the same blower technology. We’ll collaborate with you to understand your specific process and recommend the most efficient and reliable technology for your site,” he said.
“We always listen and work with each of our customers to find the best solution for them.
We’re not just offering the customer one type of technology – we’re providing them with the right technology.”
or more information, visit www.atlascopco.com/en-au/compressors
