Mott Macdonald: Wastewater Treatment Plant – Reactive Support Helps Client in Need



Improved understanding of pumping unit

‘Instant’ support ensured deadline

SUMMARY

Mott Macdonald needed extra engineering capacity with the right level of skill and experience to help them hit their tight deadline. They required complex CFD modelling to assess the solid settlement and minimum water level in the pumping unit sump of the sludge balancing tank, for the phase 2 expansion of the Changi Water Reclamation Plant. We worked with their engineers to refine the scope of work ensuring the most effective approach with regards to time and value.

SITUATION

We were asked to provide Computational Fluid Dynamics support to the Mott Macdonald Singapore team leading on the Mechanical & Electrical (M&E) package of work for the Changi Water Reclamation Plant (CWRP) phase 2 expansion (C22B) project. The CWRP is one of the largest and most advanced reclamation facilities in the world. It treats about half of Singapore’s water converting it into purified drinkable water. This is just one of the many Public Utilities Board (PUB) developments with the aim of securing Singapore’s water security for the long-term future. This expansion will increase the CWRP treatment output by 44 million gallons per day.

CHALLENGE

The Public Utilities Board are a modern organisation that embraces and frequently requests the use of simulation and analysis in their project tenders to show validation of hydraulic performance for any process or structure being built. In this case, Mott Macdonald was required to carry out particularly complex CFD modelling which covered the assessment of solid settlement and minimum water level in the pumping unit sump. Timescales were also critical.

SOLUTION

We are experienced in carrying out transient multiphase and free surface fluid flow analyses and were able to provide rapid support to ensure that Mott Macdonald could meet their deliverables. We worked with Mott Macdonald's engineers to refine the scope of work ensuring the most effective approach with regards to time and value. The first assessment covered a multiphase (sludge and water) steady-state incompressible isothermal analysis using a Eulerian-Eulerian approach to assess sludge distribution of the flow ensuring no major solid settlement. Assessing the minimum water level of the pump sump and occurrence of air entrainment involved running a multiphase (air and water) incompressible isothermal analysis using the Eulerian-Eulerian approach with a free surface model. We presented the results showing limited settlement and no air entrainment in the pump sump to the client within a detailed report.

BENEFITS
  • We improved the understanding of the volume of sludge settlement and how this is affected by flow rate.
  • We increased confidence in the behaviour of the pump following the prediction of low levels of air entrainment at its inlet.
  • We provided ‘instant’ support ensuring Mott Macdonald met their deliverables


Mott Macdonald needed extra engineering capacity with the right level of skill and experience to help them hit their tight deadline. They required complex CFD modelling to assess the solid settlement and minimum water level in the pumping unit sump of the sludge balancing tank, for the phase 2 expansion of the Changi Water Reclamation Plant. We worked with their engineers to refine the scope of work ensuring the most effective approach with regards to time and value.



We were asked to provide Computational Fluid Dynamics support to the Mott Macdonald Singapore team leading on the Mechanical & Electrical (M&E) package of work for the Changi Water Reclamation Plant (CWRP) phase 2 expansion (C22B) project. The CWRP is one of the largest and most advanced reclamation facilities in the world. It treats about half of Singapore’s water converting it into purified drinkable water. This is just one of the many Public Utilities Board (PUB) developments with the aim of securing Singapore’s water security for the long-term future. This expansion will increase the CWRP treatment output by 44 million gallons per day.



The Public Utilities Board are a modern organisation that embraces and frequently requests the use of simulation and analysis in their project tenders to show validation of hydraulic performance for any process or structure being built. In this case, Mott Macdonald was required to carry out particularly complex CFD modelling which covered the assessment of solid settlement and minimum water level in the pumping unit sump. Timescales were also critical.



We are experienced in carrying out transient multiphase and free surface fluid flow analyses and were able to provide rapid support to ensure that Mott Macdonald could meet their deliverables. We worked with Mott Macdonald's engineers to refine the scope of work ensuring the most effective approach with regards to time and value. The first assessment covered a multiphase (sludge and water) steady-state incompressible isothermal analysis using a Eulerian-Eulerian approach to assess sludge distribution of the flow ensuring no major solid settlement. Assessing the minimum water level of the pump sump and occurrence of air entrainment involved running a multiphase (air and water) incompressible isothermal analysis using the Eulerian-Eulerian approach with a free surface model. We presented the results showing limited settlement and no air entrainment in the pump sump to the client within a detailed report.



  • We improved the understanding of the volume of sludge settlement and how this is affected by flow rate.
  • We increased confidence in the behaviour of the pump following the prediction of low levels of air entrainment at its inlet.
  • We provided ‘instant’ support ensuring Mott Macdonald met their deliverables
Fluid Domain Model of Sludge Balancing Tank
Isovolume of sludge build up at a certain flow rate
Minimum water level result plot
Velocity Contour Result

SECTOR

PROJECT ATTRIBUTES

ANSYS CFD

Multi-phase

Free surface modelling


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Public Utilities Board frequently request the use of simulation and analysis in their project tenders

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