Peristaltic Pumps Are Ideal For Use In Wastewater Treatment Tasks

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Verderflex Peristaltic Pumps

Verderflex Dura

A wastewater treatment plant in Eagan, North Minnesota, USA needed a pump for repeated and accurate dosing of 15% sodium hypochlorite otherwise known as 'hypo'.

Hypo is incredibly useful in the treatment of wastewater as it has incredible disinfection capabilities. It is so effective it is used as a key method to disinfect water for human consumption. Unfortunately Hypo is a difficult material to pump as it has a tendency to off-gas which can cause vapour locks in most types of pump, especially diaphragm pumps.

The water treatment plant considered many different options from a variety of companies but finally chose the Verderflex VF10 peristaltic pump. The reasons for choosing this pump include the high flow rate, 48 US gallons per hour at 175 psi and the ability of the pump to repeatedly and consistently dose an exact amount of Hypo. Ten pumps were acquired and were put to immediate use in the plant.

Peristaltic pumps have become the pump of choice for wastewater dosing tasks and Verderflex pumps are now in use at many wastewater treatment facilities throughout the world.

Peristaltic Pump Operation

Peristaltic pumps are ideal for dosing purposes due to the way they work. The fluid in the hose is driven forward by a rotating lobe. As the lobe continues to rotate a vacuum is created in the hose, drawing more fluid in. This action is generally known as peristalsis, it is predominantly chosen for dosing purposes, as the exactly same amount of liquid is drawn in with each cycle of the lobe.

The staff at the Eagan Wastewater Plant were pleased to learn the Verderflex pumps were very cost efficient due to the hard wearing nature of the hoses. When the hoses did need replacing it was a simple operation.

“We were really pleased with the installation at the treatment plant. There were many other pumps considered for this application but in the end easy maintenance, proven reliability and exceptional hose life of the superior Verderflex design won out,” explained Tom Eisemon, National Sales Manager of GPM Pumps, primary Verderflex distributor for the US. “As a result of this installation, a similar project located nearby chose Verderflex for these same reasons and a third customer in the state recently purchased a new Verderflex DURA after hearing all the positive feedback and the new features of this design. These pumps have certainly been a success for us in this industry.”

Peristaltic pump operation is, by design incredibly simple. The fluid only ever comes into contact with the hose which ensures the pumps are very hygienic but can never clog due to the lack of moving parts. The pumps are virtually maintenance free with the changing of the hose being the only task. The hose can be changed quickly which ensures a minimum of downtime.

Water Treatment Plant Pumps

Verderflex peristaltic pumps are also ideal water treatment plant pumps for a range of other tasks. The chemicals used to balance the pH of wastewater such as Lime, Kalic® and Kalkmich are quite abrasive and can cause significant wear issues for progressing cavity pumps. Lime is also a fairly viscous material causing it to clog diaphragm pumps casing them to need a high level of maintenance.

However peristaltic pumps can comfortably pump abrasive materials and are able to pump any fluid no matter how viscous. The action of a peristaltic pump ensures the product is continually in motion and never has the chance to settle. Solids can be added into the liquid on site and cause any issues for the pumps. Because the pumps operate at a linear flow speed they are suited to feedback control systems which can accurately control the dosing of the chemicals ensuring no wastage.

Polymer Dosing Pump

Another common water treatment application is polymer dosing. Polymers are added to the water in clean water plants to remove residual colours and suspended soils. The addition of polymers is of the greatest importance as they are so effective at separating solids from the water, this enables a sizeable increase in the volume of water to be treated. Unfortunately polymers are acutely shear sensitive and in other types of pump the polymers can be damaged and become ineffectual. The pumping action of a peristaltic pump is so gentle that you can be confident that the polymers will not be affected.

Once the water has been treated the waste materials have to be made ready for disposal. The standard solution being the use of a filter press. However the waste is often abrasive and can significantly reduce flow rates. In response the pump speed is increased and the gland seals pressurised. This will help to increase flow but leakage is also increased putting the pump at risk from damage by the abrasive waste.

The consequence of these factors is suction performance will fluctuate. When the pressure increases it is not uncommon for 'rat holes' to appear in the filter press feed which causes water to be pulled in from above the sludge blanket. Therefore a greater volume of water will be included in the waste, decreasing efficiency and increasing costs.

Fortunately Verderflex products are ideal for use as a polymer dosing pump as they are able to maintain a linear suction capability and will resist wear from abrasive materials. These factors have allowed peristaltic pumps to become the global standard choice for the optimisation of the filter press operation for water treatment plants.