Wastewater air intake efficiencies to save utility up to £300,000 per year

A water company in England has reduced energy costs by between £150,000 to £300,000 per year by improving the air delivery system at a wastewater treatment plant...

LONDON, England, July 22, 2011 -- A water company in England has reduced energy costs by between £150,000 to £300,000 per year by improving the air delivery system at a wastewater treatment plant.

Wessex Water completed the £400,000 upgrade, which included introducing improved diffusers and a better designed delivery system, to reduce the air demand from 18,000 m3/hr to less than 5,000 m3/hr by using a fine bubble diffuse air system.

Modifications were carried out while the facility remained in operation. As part of the upgrade, diffusers on four basins were replaced, with each one taking two to three weeks to complete.

Dave Durkin, Wessex Water’s head of operational services, said: “Work involved sequentially draining down the four basins, each containing 6.5 million litres of effluent, while maintaining the overall operation of the plant.

“Since the capacity of the site was reduced during the work, it was carried out under the sanction of the Environment Agency, which visited the site to witness the work. Once drained and cleaned, 2,000 diffusers and 1 km of pipe work was installed in each basin, before the unit was partially refilled, tested, and then re-commissioned.”

Wessex Water said the modified treatment process provided better effluent quality and with less air consumption the treatment plant had a lower carbon footprint. The firm may look to roll out similar energy reduction schemes at sites in the region it serves.

Aeration is commonly blamed for high energy requirements at wastewater plants, in some instances accounting for up to 30% of operating costs. New technology solutions are being developed to help introduce more energy efficient aeration processes (see June-July Water & Wastewater International (WWi) article).

Last week Swedish firm Sorubin announced it had received five new orders for its Microluft aerators, claimed to improve energy efficiency by 20%, following a trial with utility Scottish Water (see WWi story)

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