WATER & WASTE TREATMENT


Sponsored by PUMP HELPS MAKE WASTE LESS WASTEFUL


A long-life Bredel hose pump from Watson- Marlow Fluid


Technology Solutions (WMFTS) has replaced a faulty progressive cavity pump at


Scheldestromen water board’s treatment plant in the Netherlands


• A Bredel hose pump is transferring


thickened sludge at a treatment plant of Scheldestromen water board in the Netherlands • A Bredel peristaltic hose pump replaced


a faulty and costly progressive cavity pump • The sludge is used in the production of


biogas, and processed into solid digestate for use as fertiliser


A


Bredel peristaltic hose pump has shown the ideal qualities for transferring thickened sludge in the


production of biogas for Scheldestromen water board (Waterschap Scheldestromen) in the Netherlands. The Bredel 65 hose pump is transferring


polymer-thickened sludge of 6 to 8% to tanks for fermentation at the water board’s treatment plant in Terneuzen, Zeeland. A progressive cavity pump was proving too


costly with a short lifetime for transferring sludge, lasting two and a half months on average for a stator and stator rotor, which resulted in maintenance downtime. Dimitry Loof, Work Planner at


Scheldestromen water board, said: “It was a consideration between costs and benefits to change pumps, and also a short service life of the progressive cavity pump. We wanted to extend the service life of the pump for this application.” Over the course of the three months, the


progressive cavity pump’s capacity continued to decline. This meant Scheldestromen water board had to speed up the progressive cavity pump to be able to use the same flow rate. When the pump was running at the end of its range, the water board could no longer absorb fluctuations in the process, resulting in a failure and a backlog in its total sludge processing flow. The progressive cavity pump suffered a lot of wear in the stator and rotor due to sand,


22 NOVEMBER 2024 | PROCESS & CONTROL


which caused pressure loss and the capacity to decrease. To replace a stator and stator rotor cost Scheldestromen water board a total of 3,000 euros (excl. VAT), as well as the time it took staff to do the pump maintenance. The stator and rotor had to be replaced three or four times per year. Gertjan Dijkers, Process Operator at Scheldestromen water board, said: “The progressive cavity pump’s problems were largely caused by sand and the pressure pipe that was too small. The pressure pipe had a relatively high resistance. This was partly due to the long distance, a number of right-angle bends in the pipe and a relatively small cross- section of the pressure pipe (100mm). This, in combination with a dry matter content between 6% and 8% (sludge and sand), ensured that the pump had a high back pressure. This caused the pump to wear out quickly.”


Due to the unreliable operation of the progressive cavity pump, Scheldestromen water board could not be certain it could process all the sludge supplied from the treatment plants.


Longer service life


Looking for a better performing pump with a longer service life, the water board met with Watson-Marlow Fluid Technology Solutions (WMFTS) to explore how Bredel hose pumps could be a solution. They also contacted another peristaltic pump supplier, a lobe pump manufacturer and a progressive cavity pump manufacturer.


Gertjan Dijkers, Process Operator at Scheldestromen water board, said: “We just wanted to be able to run for at least three months with the flow rate that we have to run. We have found that a Bredel hose pump can run for over three months before its capacity starts to decrease. The biggest advantage is that the hose pump simply does what it is


supposed to do for over three months.” Bredel hose pumps have no rotating parts to clog or wear with the sand, which considerably reduces maintenance and labour costs. As well as costs, the Bredel hose pump brings ergonomic benefits. Scheldestromen water board did not have to increase the diameter of the piping, which built up too much with the progressive cavity pump. The accessibility of the pump is much better with the Bredel, and because of the suction capability of the Bredel it is located on the ground floor.


Scheldestromen water board calculated it can have a return on investment on the Bredel pump in four years and make savings on maintenance compared to the previous progressive cavity pump.


Maintenance costs and labour costs of the progressive cavity pump per year (average taken over six years) were 9,420 euros, according to Scheldestromen water board. They calculated it will make 42% savings in annual maintenance costs with the Bredel hose pump, compared to the previous progressive cavity pump. Another benefit for Scheldestromen water board is that a single operator can now change the pump hose without another co-worker’s assistance. Ed Zorg, Industrial Sales Engineer for WMFTS in Netherlands, said: “Scheldestromen water board chose the Bredel pump for a few reasons. The other options were not a solution. The lobe pump had difficulty delivering high pressures above 4 bar, and the parts would wear out. The other manufacturer of peristaltic pumps did not have a pump available with the right size for this application as a test setup.


“Another important reason why Scheldestromen water board chose us was the relationship we developed with them. We were able to quickly provide a demonstration pump from our Bredel factory, so they could


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