Monster sludge calls for monster pumps

A huge plant treating the effluent of 1.8 million people called for a unique pumping solution.

The Mogden plant, located in the UK, was built in 1936 for the West Middlesex drainage district to replace 28 small sewage treatment works. Over the years it has been expanded, still within the original site boundaries, to now treat the effluent of approximately 1.8 million people.

The plant produces some 96,000 tonnes of sludge cake every year, all of which is recycled to land. Chiswick, Wembley, Edgware, Ruislip, Harrow, Staines and Hampton mark the limits of its catchment, with the River Thames the southern boundary. The plant has a capacity to treat 810 million litres of liquid waste each day. It’s a large site with large maintenance demands, and Thames Water required an appropriate maintenance plan to be established to keep the new pumps at their optimum performance.he Mogden plant, located in the UK, was built in 1936 for the West Middlesex drainage district to replace 28 small sewage treatment works. Over the years it has been expanded, still within the original site boundaries, to now treat the effluent of approximately 1.8 million people.

The situation

The SEEPEX pumps in use at Mogden are used for a variety of applications, from small dosing pumps with liquid polymers to large transfer pumps. Most however are used in the sludge treatment processes from mechanical thickening to pasteurisation, and they handle a variety of different sludges at varying densities and temperature. Each pump is specified particularly for its duty, with consideration of all the varying factors to ensure the pumps are left to operate at their optimum efficiency with minimal downtime.

Mogden is also the home of the monstrous SEEPEX N300-36 sludge surface transfer pumps which transfer 180m³/hr of sludge 16km to another treatment plant. These pumps are fitted with massive 250kW energy efficient electric motors and provide a combination of flow and pressure unmatched worldwide.

With 16 weeks to implement – a record-breaking time frame – a project team of 30 spanning all departments within the company designed, manufactured and delivered these giant pumps. At 11m long and almost seven tonnes in weight, they represent a new milestone in the development of progressive cavity pumps, enabling the company to penetrate markets that are traditionally associated with large piston pump technology.

The core of the progressive cavity pump, the rotor, was manufactured from one single piece of tool steel which initially consisted of a billet weighing 1.7 tonnes and finally ended up at 0.7 tonnes  and almost 6m long and within accuracies of 0.2mm.

The stator concept utilised considered aspects of health and safety relating to manual handling, during both assembly and future servicing whilst ensuring optimum pump performance.

The solution

SEEPEX were asked to offer service capabilities to assist Thames Water with planned and reactive maintenance to some of the more specialised SEEPEX progressive cavity pumps and associated grinders. The service had to be comprehensive, cost effective and reliable in order to meet the high demands of running the third largest effluent treatment plant in Europe.

SEEPEX started by delivering this service by means of a monthly service visit to check and maintain just 28 of the 55 pumps and to take care of any maintenance interventions identified as a result of the checks. This reduced the sludge pump downtime so successfully that SEEPEX were soon asked to take on more pumps.

The giant pumps manufactured by SEEPEX

The benefit

Since their installation in 2003 these massive pumps have been pumping sludge 16km day in and day out without the use of any spare parts.

SEEPEX now has responsibility for all of the SEEPEX pumps at the site and also all of the pumps at Mogden’s sister site Iver South in Slough. SEEPEX had proved it was much more than a pump supplier, and that the service consultation package offered delivers less repairs, less downtime, less usage of parts and more importantly reduced costs of ownership.

SEEPEX UK is contracted to carry out planned and preventative maintenance to a total of 68 progressive cavity pumps and grinders at two sites ranging from polymer dosing pumps to massive sludge transfer pumps. Checks are thorough. Dry run, over pressure, wear, drive condition and efficiency are all checked on a monthly basis. Wear rates are predicted as a result of these checks and preventative interventions are carried out before downtime occurs and when required they are carried out within one working day, on site. As a result neither site has experienced any unplanned downtime due to sludge pump failure since the agreements were put in place.

Key Facts

• Flow rate and pressures unmatched worldwide
• Record-breaking time from concept to delivery
• 1.7 tonnes to 0.7 tonnes with accuracies with 0.2mm
• Service consultation package

Significant Cost Savings

• Efficiently transfer thickened sludge 180m³/hr 16 km
• Less usage of spare parts
• Less repairs
• Less downtime
• Labour cost saving

Installed Pump Type

• Range N

For further information on how these technologies and principles can benefit local sewage installations, please contact SEEPEX Australia on 02 4355 4500 or [email protected]

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