The Challenge:

Plymouth Central treats over one third of Plymouth’s wastewater catchment, serving a peak population equivalent of around 118,000. Due to its coastal location, the site receives and treats water with higher proportions of saline and fat than those in-land. Subsequently, the treatment process at Plymouth is more complex compared to other South West Water sites located in-land.

Centrifuges have dominated the sludge dewatering market for years. This is due to their ability to process large volumes of sludge in a single unit at lower capital costs to alternative methods.

South West Water approached Kier to research alternative dewatering technologies with lower Total Expenditure (TOTEX), looking to replace existing ageing centrifuge assets with a number of key drivers, including; reduction in power and polymer consumption, reduction in transport costs and improved odours capture.

The Solution:

The Q-Press dewatering scheme was extensively trialled, with impressive results showing considerable benefits to whole life costing and net present value. Additional benefits of the Q-Press include:

  • The availability of four different sizes dependant on demand, with the largest unit processing over 500kg of sludge an hour
  • Providing a more reliable and user-friendly operating system for sludge dewatering
  • A more cost-effective solution for water companies, with lower operating costs compared to more conventional solutions.

The new scheme challenges the concept of having a single centrifuge by replacing it with three Q-Press machines, providing some redundancy. The HUBER Q-Press holds a proven track record within industrial applications in the UK, however no water utilities had used the technology on a municipal site up until this project, highlighting this scheme as a first of its kind.

The Impact:

The Q-Press solution delivers the following TOTEX benefits when compared to a centrifuge scheme:

  • 40% lower chemical consumption, leading to significant cost savings and carbon reductions
  • 90% power savings as a result of using a single low powered drive to rotate the drum, leading to significant cost savings and carbon reductions
  • 50% savings on annual operating costs
  • Increase ease of operation and maintenance
  • Reduced odour treatment required, enabling safer on-site working conditions
  • 22% saving on 20-year net present value
  • 19% reduction in transport costs as a result of drier cake, which equates to approximately £66,000 per annum
  • A modular design, allowing the scheme to be scaled up/down as demand requires.

Ofwat’s PR19 review highlighted the expectation of water companies to view their sludge business separately to their wastewater one, shifting priorities and company demands. The Q-Press is an ideal solution for water companies looking to meet these Ofwat objectives.

Watch a video of the HUBER Q-Press

" The Q-Press will have extensive impact on the water industry, with reduced chemical, power and maintenance costs driving OPEX savings year-on-year, compared to previous centrifuge schemes. The reduced odour emission rate further increases site efficiencies, reducing the risks of odour nuisances and improving working conditions for operators. "
David Parker Engineering Manager Kier group

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