Atlas Copco has launched a range of oil-free screw blowers designed to cut the energy used in wastewater aeration, one of the most energy-intensive stages of the treatment process. The company says its new ZS 4 (VSD) range, which uses a variable-speed drive and a dedicated low-pressure screw element, can be up to 35% more energy-efficient than the lobe blowers still widely used in aeration basins.
Why aeration energy matters
Biological treatment, in which air is pumped into tanks to sustain the micro-organisms that break down pollutants, typically accounts for 60 to 80% of the energy used at a wastewater treatment works. Cutting that demand has become a priority for utilities, particularly in England and Wales, where water companies are investing heavily in upgrades under the regulator Ofwat’s AMP8 cycle (2025 to 2030) while under pressure to control costs and carbon. Improving the energy efficiency of the water industry is one of the sector’s biggest operational challenges.
What Atlas Copco says about the ZS 4
The ZS 4 (VSD) is available in a power range of 37 to 90 kW and is built around a low-pressure screw element rated for the sub-1-bar pressures used in aeration. According to Atlas Copco, the variable-speed drive and a high-efficiency IE4/IE5 motor allow the blower to match air output to demand while maintaining stable airflow, improving the specific energy requirement by around 3% over the previous generation.
The company says the range carries Class 0 oil-free certification under ISO 8573-1, meaning no compressor lubricant can enter the air stream, a consideration for the biological process the air supports, and that noise levels can be as low as 75 dB(A). It adds that the design reduces maintenance requirements and whole-life cost compared with conventional blowers. New wastewater treatment technologies increasingly pair high-efficiency equipment with controls that match air supply to real-time demand.
Frequently asked questions
What is the Atlas Copco ZS 4 (VSD)?
A range of oil-free, variable-speed screw blowers for wastewater aeration, available from 37 to 90 kW.
How much energy can it save?
Atlas Copco says the blowers can be up to 35% more energy-efficient than traditional lobe blowers, with around a 3% improvement in specific energy requirement over the previous generation.
Why is aeration energy a focus for water companies?
Aeration in biological treatment typically accounts for 60 to 80% of a wastewater works’ energy use, so reducing it has a large effect on operating costs and carbon, a priority under the UK’s AMP8 investment cycle.
What does “oil-free” mean here?
The blower carries Class 0 certification under ISO 8573-1, meaning no compressor lubricant can enter the air delivered to the aeration process.
