Blow to energy costs at Anglian Water

London –  Anglian Water has selected Atlas Copco’s low-pressure ZS blowers to supply air to the aeration diffusers at four of its wastewater treatment re-development sites.

A total of the rotary screw blowers will be installed at the sites in Colchester, Letchworth, Bedford and Flag Fen, near Peterborough as part of an Anglian Water initiative to find new ways of reducing its energy costs.

Wastewater treatment plants use bacteria to break up waste which requires large quantities of air to be blown into aeration tanks. In a typical biological wastewater treatment plant, the blower system will account for up to 70% of energy usage.

Anglian Water approached Hydrok, an aeration diffuser and IFAS company, about supplying submerged, high-efficiency, bubble aeration framework systems incorporating bio textile curtains and fixed bed media.

These units improve the distribution of aeration air to maintain the desired level of dissolved oxygen within the wastewater containment system.

Hydrok matched its high efficiency diffuser technology with Atlas Copco ZS low pressure screw blowers, which make energy cost savings of up to 35% possible, for optimum performance.

The variable speed drive, oil-free rotary screw displacement blowers comprise an integrated package based on an internal principle: precision timing gears maintain minute clearances between two intermeshing oil free screw elements that never touch.

No lubrication is required in the compression space and special seals stop any rotor bearing oil from entering the compression chamber. Intake air is compressed between the rotors and their housing and oil-free, pulsation-free air at pressures of 550-700 mbar is delivered at an output rate of between 1300 - 4500 Nm3/h free air delivered dependent upon process demand.

The blowers fitted with weather proofing kits for external installation are being installed at Anglian Water’s wastewater plants in Flag Fen and Bedford. Anglian Water to locate the blower motor inverters, controls and condition monitoring in a purpose built MCC room.

At the Letchworth and Colchester sites, the blowers will be located within an existing plant room. In the case of the Letchworth site Anglian Water also chose to reduce installation costs by installing ZS+ blowers, which are supplied with an integrated frequency converter.

This varies the speed of the 90kW motor to match changes in the blower air demand, thus consuming only the minimum amount of energy. The blowers are fitted with Atlas Copco’s Elektronikon operating system to provide control, to monitor the overall system performance status