An energy-saving pump is set to provide clean water in Pien-Saimaa

A new pumping station intended to purify the water in the Pien-Saimaa area of Lake Saimaa is approaching completion in Kivisalmi, Lappeenranta.  Work will begin on the installation of the pump in week 9. Testing and full use should then follow in the same week. The energy-saving pump has been designed entirely in Finland, as a result of research conducted at LUT.

The Kivisalmi pump station's energy-efficient pump was designed by LUT professors, Jaakko Larjola and Juha Pyrhönen. The new pump is intended to speed up the work to improve the water quality in in the Pien-Saimaa area of Lake Saimaa. Currently, the water purity level in this area of the lake is somewhere between poor and adequate.

"The northern and western parts of Pien-Saimaa are suffering from the effects of eutrophication and the presence of cyanobacterial blooms. Also, Pien-Saimaa is shallow and partially isolated, thus making the waterflow slow. As such, controlling the supply of supplementary water is a big part of supporting the other restorative measures being taken", explains Ilkka Räsänen, Director of Environmental Services for the Lappeenranta Region.

The completion of the pump was slightly delayed owing to a change in one of the subcontractors on the project. The manufacturer of the pump's impeller blade had to be replaced, which resulted in a delay of around 6 months.

Better than the traditional solutions

According to calculations, the unique LUT-designed pump will reduce energy costs by around EUR 30,000 a year in comparison to the best commercially available alternatives. Lappeenranta's Environmental Services decided that the pump should be powered by wind turbines, significantly reducing its carbon footprint. Solar panels were another alternative. On this occasion, however, the decision was made to go with wind power.

The new pump can transfer vast quantities of water and only generates enough lifting height as is needed in order to maintain the desired waterflow. In relation to its giant size, the pump is inexpensive, ecological, and has very low maintenance requirements. In fact, it uses between 17% and 33% less energy than the equivalent commercially available pumps.

The pump has a large impeller diameter, a new kind of blade, correctional blades, oil-free direct drive, and a low-speed, high-torque permanent magnet synchronous motor. The motor is powered by a frequency inverter and the corner blades of the impeller can be adjusted when needed. This is one of the ways in which the pump's energy consumption can be kept to a minimum. The pump has been supplied by WP Waterpumps Oy and its motor manufactured by AXCO Motors Oy. In fact, it has been designed and manufactured entirely in Finland.

"This pump represents brand new technology and is unique on a global scale", reveals Professor Juha Pyrhönen from LUT. The aim is to productise the pump and launch it in global markets. And there is an abundance of potential applications, as stagnant or standing water sources can be found around the world.  "We have even given this brand new kind of pump a name – ProPurAqva – which means 'for the sake of clean water'", explains fellow LUT professor, Jaakko Larjola.

An open-minded approach from the City of Lappeenranta

"The City of Lappeenranta had a completely open-mind when they chose the pump designed at LUT.  The deciding factors were the energy-efficiency of the pump and its overall green credentials", says Lappeenranta's Director of Environmental Services, Ilkka Räsänen.

The Pien-Saimaa area is extremely important to the success of the Western Saimaa region. The City of Lappeenranta uses the water drawn from Pien-Saimaa to produces artificial groundwater in its Huhtaniemi water intake.  This water supplies around 40,000 homes in the area. The Pien-Saimaa waterway is also very important to hobbyists and tourists who use it for recreational purposes.

Monitoring the impact of the pump

The pump will be monitored from the moment it is installed and the testing commences. Particular attention will be paid to any changes in the water quality. In addition, the impact that the pumping station has on ice levels will also be monitored. Even though the pump transfers a notable amount of water (approx. 10 m3/s i.e. around 300 million m3 per year), it only makes a small impact on the speed of the current in the waterway. There might, however, be some changes in the freezing conditions of the water, primarily in Kivisalmi. The melt-water areas in Kirjamoinsalmi and Voisalmi may also grow.

Following the pump installation

The installation of the pump is a major undertaking. First it has to be transported to Lappeenranta in two parts by a specialist haulier before it can be assembled in Kivisalmi. A crane will be required to lift the 6x6x4 m3 pump unit into the water channel. The installation can be followed from the pedestrian lane on the Kivisalmi bridge. A precise schedule  will be announced in the current events section of the City of Lappeenranta website.

Additional information:

About the pump:

Professor Jaakko Larjola, tel. +358 (0)40 505 3322,

Professor Juha Pyrhönen, tel. +358 (0)40 571 1645,             

About the installation:

Director of Environmental Services Ilkka Räsänen, tel. +358 (0)400 815 284,

Project Coordinator Raija Aura, tel. +358 (0)40 5843 278,