18 utilities & Wastewater
Tackling the wet wipe dilemma
Suzanne Gill finds out how pump system providers are helping the utility and wastewater industries to overcome the challenges posed by the increasing quantity of wet wipes and other solid products in systems and networks.
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very year UK utilities spend around £100 million clearing an estimated 300,000 fatbergs from the sewerage system. These blockages are made up of congealed fats, oils and grease (FOG), mixed with ever-increasing quantities of solid waste that has been deposited into the network, such as wet wipes. Although promoted as flushable, single-use wipes do not break down in the same way and in the same timeframe as toilet paper and handling these ‘disposable’ products is becoming a serious problem for utilities and wastewater systems. Indeed, wet wipes are believed to be responsible for 80% of blockages in sewer systems today. System failure due to blockages can require costly manual attendance – often in confined spaces. It can lead to the need for emergency tankering, equipment removal, and cleaning, in addition to strip down and repair of the pump. Attempts to combat the problem can include the installation of macerators and choppers in the system. However, over time, the cutting action of these solutions can become less effective as the wearing parts become blunt and so regular maintenance is often still a necessity. “We believe the answer to the majority of blockages is free passage,” said Paul Walthew, Business Development Manager – Site Services at Caprari. “In our three and four-inch adoptable sewage pumping stations we endeavour to install, where possible, vortex and channel impeller pumps matched to the pipework size to enable what enters the pump to be passed through the pumping station pipework.” The Caprari KCW range has a large free passage – 80mm & 100mm on 3in and 4in branch sizes respectively. “We have teamed these with other technologies, such as fibre cutting and back impeller cleaning, to ensure that the pump is efficient and fights against blockages effectively. We have also installed telemetry units on pumping stations to monitor performance and combined with regular maintenance, we have seen reactive callout intervals now being measured in months – and in some cases years!” CUTTING-EDGE DESIGN NOV, formally Mono Pumps, has been providing heavy-duty wastewater grinders for over 30 years and its Muncher range of twin shaft, slow speed,
Quarter 3 2019
high torque grinders are used by all the major UK water companies, along with many private operations such as airports, hospitals, hotels, shopping centres and leisure facilities. “In recognition of the increasing use of wet wipes and other one-use disposable products, NOV conducted several operational performance trials to measure the effectiveness of grinding this fibrous product to an acceptable and handleable particle size to significantly reduce pump station blockages,” said Ian Hallows, Business Development Manager at NOV. “Our Muncher grinders are fitted with ETOS cutters which offer positive and effective solids maceration and which have been designed specifically for the effective processing of products such as wet wipes.” The ETOS cutters provide effective maceration with the cutter shafts operating at differential speeds to exert a tearing action on the solids. The off-set tooth design of the cutter reduces impact load and power. The saw-tooth profile of the ETOS cutters offers greater strength, while its close machining tolerances offer less clearance and ‘chatter’ on the shaft. The design includes a serrated tooth profile to snag and hold textiles, and a large circumference gives less clearance and better grinding.
The asymmetrical blade arrangement of the KSB F-M impeller allows solids of different sizes to pass easily.
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