Thames Water prevents pump blockages, minimizes downtime

The high performance TR Muncher from Mono® NOV, Europe's leading designer and manufacturer of pumps, parts, grinders, screens and packaged systems, has been installed by Thames Water to improve efficiency at Bracknell Sewage Treatment Works by preventing pump blockages and minimizing down time.

Bracknell Sewage Treatment works is one of Thames Water's 349 sewage treatment facilities. It features seven primary sludge tanks, which, due to the high rag content of the sludge, required frequent maintenance, cleaning and equipment repair.

To provide a solution to this problem, Thames Water specified Mono's TR Muncher, which macerates heavy solids and rags to a small particle size to protect the plant's process equipment.

The installation of the TR Muncher, together with the re-location of the existing Mono Munchers on the site, was undertaken by Mono's Projects and Installation team, and included mechanical and electric installation, commissioning and handover.
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Amanda Stern, Bracknell Area Team Manager, commented on the project: "We specified Mono for a number of reasons; not only did they come on recommendation from an internal source at Thames, but to us, the company is tried and tested, we know their products offer an efficient solution and we are more than happy with the level of performance they deliver.

"Throughout the installation project the Mono installation team had everything under control, including health and safety and keeping the site tidy. I would happily use them again and would willingly recommend their services to my colleagues."

The TR Muncher, which has a capacity range of 0-500m³/h raw sewage, features the latest generation of twin shaft grinders and is designed specifically for the efficient treatment of abrasive sludges.

The differential speed of the cutter stacks pulls apart fibrous material, whilst the leading edge and sides of the cutter teeth crop and shear other materials such as plastic into small pieces. The circumferential 'land' of the cutter crushes friable or brittle material and the pull back cutter stack allows removal without disturbing the pipeline.

The layback cutter shafts on the TR Muncher are set at an angle to the incoming flow. This more effective design allows the Muncher to capture irregular shaped objects and, if a reverse cycle occurs, the object is automatically dropped into the built-in trash trap, which is set clear of and below the cutter stacks, retaining the solids away from the cutters. A trash flap is fitted with a large diameter access port to enable easy removal, cleaning and flushing.

The cantilever shaft design of the TR Muncher eliminates the need for bottom bearings and seals, significantly reducing wearing components. Each Muncher is supplied with a programmable logic controller (PLC) to protect the machine against damage and overloads.

Packaged Systems
Packaged pumping systems have now been developed to pump and macerate waste in a single operation, providing a more and effective and safer option than operating and maintaining submersible pumps in a sump.

These innovative systems enable efficient sewage collection, while satisfying health and safety requirements and legislation. They control cost and energy use, by delivering effective sewage transfer with ease of access, installation and maintenance - typically they consume less than 50% of the energy of conventional centrifugal sewage pumps.

The packages can be installed into existing pump stations or pre-assembled into an insulated glass reinforced plastic (GRP) kiosk, which contains the required pump and grinder control equipment and necessary pipework for rapid installation.

Packages usually combine a positive displacement pump with a solids grinder, such as the TR Muncher, which enable the use of a 'small bore' rising main system. This involves significantly lower installation costs compared to a traditional 100mm rising main sewer -- up to 75% savings can be achieved.

The positive displacement action of the pump in the packaged system lifts the raw sewage from the sump into the cutting chamber of the grinder. The sewage and any textile and fibrous matter is macerated and then pumped away into the main gravity sewer. When the pumping cycle ends, unmacerated material falls back into the sump, clearing the suction pipe for the next dry run.

The reduced pipe size also increases the velocity of the sewage, providing an optimum flow rate, eliminating the risk of solids settlement and septicity. With this method of solids handling, the final effluent being discharged to the treatment works arrives in constant, short discharges, minimizing shock loading and downstream blockages.

Based in Manchester, Mono NOV is Europe's leading designer and manufacturer of pumps, parts, grinders, screens and packaged systems, supplying many different sectors including, water and wastewater, food and beverage, chemical and pharmaceutical, oil and gas, minerals and mining and paper and pulp.

March 2009

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