The City of Eagan in North Minnesota, US, required a pump capable of accurately dosing 15% sodium hypochlorite or ‘hypo’ for its new wastewater treatment plant.
Hypo has outstanding disinfection properties. It is used in wastewater treatment to kill off bacteria before being discharged back into the environment, and in water treatment as one of the primary methods of drinking water disinfection. It is also a challenging product to pump as, when being pumped, hypo tends to off-gas, causing some pump types like diaphragm pumps to vapour lock.
After evaluating several pump choices from a number of manufacturers, the city decided to use the Verderflex VF10 peristaltic hose pump for the job. The ten pumps will be put to immediate use in this new area of the treatment plant. Each Verderflex VF10 pump is capable of flow rates up to 48gal/hr and at pressures up to 175psi. Verderflex pumps can pump both gas and liquid, ensuring the liquid stream receives a consistent dose.
Peristaltic pumps are the perfect pump choice for dosing sodium hypochlorite and Verderflex pumps can be found in wastewater treatment plants worldwide.
The fluid being dosed is kept totally enclosed within the rubber hose which is then compressed by a rotating shoe, forcing the liquid inside along. Upon restitution of the hose the resulting vacuum draws in more liquid. This process is knows as peristalsis and is what makes the peristaltic pump the first choice for liquid metering. Variations in hose type allow for low strength and even high strength hypo dosing.
The wastewater plant needs to run as cost-efficiently as possible and the City of Eagan was impressed with the long hose life given by the Verderflex hose and the ease of maintenance when the hose needed to be changed.
"We were really pleased with the installation at the City of Eagan Wastewater Treatment Plant," said Tom Eisemon, national sales nanager, GPM Pumps (master distributor for Verderflex in US). "There were many other pumps considered for this application, but in the end the ease of maintenance, the proven reliability, and the exceptional hose life of Verderflex’s superior design won out. As a result of this installation, a similar project located nearby chose Verderflex for these same reasons and a third customer in the state just recently purchased a new Dura after hearing all of the positive feedback and new features of this design. These pumps have certainly been a success for us in this industry."
Because of the pumping process used by peristaltic pumps, the hose is the only part that ever comes in to contact with the fluid being pumped. Not only does this mean that the pump is hygienic and leak-free, it also means that there are no moving parts to become clogged or damaged. The only maintenance required is to change the hose, which is done quickly and efficiently, keeping downtime to an absolute minimum, saving costs and increasing profits.
