Reduced energy costs with Danfoss APP pumps and iSave ERDs

With its mission of supplying high-quality water at the best possible price, Suministros de Agua La Oliva, SA, has served 23,000 inhabitants and a large tourist population since 1989. In 2019, its board of directors decided that the time had come to perform a major retrofit of its RO plant.

“Board members recognized that the time had come to look for alternatives to the plant’s aging centrifugal pump,” recalls Pedro Viera of Veolia Water Technologies Iberica. “The technological advances of the last 30 years – not least in energy efficiency – make retrofits of similarly sized plants increasingly attractive, especially in locations like Fuerteventura where electricity costs are high.”

Engineers from Veolia Water Technologies Iberica worked closely with Suministros de Agua La Oliva to examine replacement options for the plant’s multistage centrifugal pump, which used 4.7 kWh/m³ to process 1,000 m³ per day.

After considering a variety of high-pressure alternatives, engineers proposed a two-train solution based on Danfoss technology. Each 1,000 m³ train consists of one APP 53/1500 high-pressure pump, one iSave 70 energy recovery device, and three Vacon 100 Flow drives (one for each train’s low-pressure seawater pump, high-pressure pump, and energy recovery device).

As is customary for Veolia Water Technologies, their local technicians worked closely with the end user throughout the design and installation phases to facilitate smooth implementation. Since installation was completed, Veolia technicians have monitored the new plant constantly to ensure utmost reliability.

According to Viera, installation of the two trains was simple and fast. Unlike larger centrifugal pumps, no special crane was required to install the lighter, more compact APP pumps. “The end user was surprised to discover how little space the two new
trains required,” says Viera.

What came as no surprise, however, was the new plant’s dependability and energy savings. Maintenance has been simple, and actual consumption is even lower than Veolia’s engineers had calculated in their bid. The retrofitted plant uses 2.0 kWh/m³ to process 1,000 m³ per day, or 57% less than the plant’s previous 4.7 kWh/m³.

“The combination of Danfoss APP pumps, iSave ERDs and Vacon 100 Flow AC drives results in extremely significant energy savings,” explains Viera. “As we have seen elsewhere, the relatively short payback time makes a very compelling case for retrofitting older RO plants. When you also consider the advantages of improved reliability and lowered CO₂ emissions, it’s clear that such retrofits are appealing to many RO customers.”