We have all seen the outside of a double disc pump but rarely do we see what makes the pump actually work. Just to review, a double disc pump is a positive displacement pump that uses a trunnion (elastomer), a disc and a connecting rod to force sewage from the suction side to the discharge side of the pump by creating a vacuum inside the pump body. The valve chambers with the black check valves you see in the photo help to manage higher than normal concentrations of grit and solids in municipal wastewater.
With pumping applications, one of the challenges you face especially when pumping thinner liquids, is to maintain continuous flow without “jerking the hose” or disruptions in pump productivity. One of the consulting engineering firms we have worked with in California illustrates this point well:
We have a rural community of about 20 residents where drinking water is not always accessible. A water truck service has been costing us a fortune to fill the residential drinking water tanks serving the homes. We are trying to reduce our budget by possibly investing in our own water trailer system but the unit has to be safe for storing and dispensing drinking water.
We get a lot of questions from WWTP’s and public works departments asking about the differences between regular trash pumps on a trailer with diesel engines and dry prime pumps. The following question from a municipal pump operator exemplifies the discussion:
Hi, we use your double disc pumps at our primary scum pumping operation but we also have a need for a dry prime pump or a regular trash pump for pumping out our digesters for
I need to outfit our 200 slip marina with new pump stations with one larger pump to feed the sewage up a 100 ft. hill at approx. a 6 degree slope. The problem is that our slips are spread out without a consistent layout. What kind of pump system do you recommend?
Orange county is home to dozens of resorts, hotels and theme parks which generate tens of millions of gallons of wastewater that needs to be treated every year. When an Orlando Florida renewable energy company earned a multiyear contract to accept waste from local resorts and theme parks, they needed severe duty pumps to transfer thick slurries and solids.
Pumping landfill leachate, wastewater containing solids and other debris is a challenging task that requires high performance pump systems to hold up to day-to-day heavy duty pumping tasks. There are added variables like solids, methane gas and potential site risks that must be taken into account when planning for a landfill wastewater and leachate pumping system.
For years, we have been asking wastewater treatment plants (WWTP) what they like about double disc pumps and what they don’t like. We have even been compiling a database with what regions of the USA and Canada have success with this type of pump for sewage and which areas have had more challenges.
One of the things that most WWTP’s say is that there has been limited competition in the specifications put out for bid by municipalities and consulting engineers working on wastewater projects. As we all know a monopoly in the pump industry is seldom a good thing for quality, innovation and of course pricing for pumps and parts.