Water a priority for Diageo

Diageo is the world's leading premium drinks business with an outstanding collection of beverage alcohol brands across spirits, beer and wine. It is committed to minimising its environmental impact across the full range of its operations, and it is working to extend environmental standards further through its supply chain.

The waste water treatment plant at Mallusk is a Membrane Bioreactor (MBR) plant. The treated water (‘permeate’) is discharged to municipal sewer. In order to operate the MBR process at optimum, it is desirable to maintain the MLSS (Mixed Liquor Suspended Solids) in the membrane tank within the range 12,000-18,000 mg/l.

This necessitates periodic removal of sludge as the concentration of the MLSS builds up. Historically site practice was to have the effluent continually recirculated within the process and periodically bulk desludging by external waste contractor. This method of operation was impairing the ETP, particularly on the performance of the MBR plant and was leading to ever more frequent clean cycles and more frequent membrane replacement. The practice was also consuming more energy to sustain and impacting the overall cost to run the works, aside from involving major manual intervention and downtime associated with biannual desludging activities.

Following extensive analysis a project to install and use a containerised dewatering plant to provide a best-fit sludge handling and removal regime was progressed.

Impact

The benefits associated with the improvement project were:

  • NIEA/ IPPC License Contract desludging as a tool to manage the excess sludge level in the ETP required concession from local Environmental Authority. The parameters for MLSS had been breached in the past due to an unbalanced desludging regime. This was putting the IPPC license for the business at risk. The Dewatering project would mitigate this.
  • Diageo Environmental Non-conformances Project helped avoid non-conformances, breaching the license and Diageo requirements. These had occurred in the past.
  • Payback Sludge disposal costs would be reduced by 45-50%
  • Reduction in energy required to sustain a healthy ETP through improved oxygen transfer into the effluent for lower energy input.
  • Strategy Project enabler to possible re-use of the ETP water
Diageo NI

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