Failure at an unmanned wastewater pump station (WWPS) would be disastrous, with contaminated water causing damage to both people and the environment. Because reliability is crucial, one Finnish utility installed ABB’s water dedicated variable speed drives to ensure effective management.
Few people outside the wastewater industry give a second thought to what happens to the volumes of wastewater produced daily from their households and industries, but it is essential that the water used goes to a treatment plant where it can be cleaned and returned safely and efficiently to the environment. Effective management In Pietarsaari, on the west coast of Finland, 80% of wastewater, 3 million m3, flows through one unmanned pumping station. With a community of 20,000, Pietarsaari is a key example of how crucial reliable wastewater management is and, with this in mind, in 2016 municipal water utility Pietarsaaren Vesi installed ABB’s water-dedicated ACQ580 variable speed drives (VSDs) to ensure its main wastewater pump station is effectively managed.
Pietarsaaren Vesi’s five submersible pumps are linked to ensure that the optimal number of pumps are operating at any given time to maintain the correct water flow. Water levels are closely monitored and the pumps adjusted as needed. If the wastewater tank suddenly starts filling up faster than normal, several of the pumps can be activated at once in order to cope with this.
“It has to be reliable. In the worst-case scenario raw wastewater would flow directly into the sea if levels rose too high in the pumping station," says Mika Dahlman, Process Manager at Pietarsaaren Vesi, which pumps around 3 million m3 of wastewater through the station every year.
Clogging problem All wastewater facilities have to deal with the problem of clogging. Over time pump impellers can be-come clogged, lowering pump efficiency and, in some cases, even causing the pump to jam completely. Cleaning by hand is time-consuming and pulling up the pumps for cleaning in a confined space with a strong flow of wastewater can pose safety hazards for maintenance personnel.
Due to the pumping station being unmanned, a remote monitoring option to access drive data is essential for reducing the amount of routine site visits. The new drives have several built-in functions including the pump cleaning function which can be scheduled without interrupting the normal pumping duty. This reduces downtime and lowers manual cleaning costs, while improving pumping efficiency.
Perhaps one of the most attractive features of the ACQ580 drive is that it is so easy to use. “The approach taken in these drives is similar to the approach – just plug and play, and you’re ready to go,” says Andreas Ek, the specialist in charge of installing and commissioning the new drives for technical support company Pietec.
Control panel design The drives are designed to speak the operator's language and Mika Dahlman has praise for the usability of the control panels. ”The layout of the drive display is more lucid and easier to use. The menu is more logical, more clearly showing amps for voltage and current, rotation speed and direction, and other important data.”
But it is the reliability of these drives, even in the tough conditions present in wastewater pumping envi-ronments, that sets them apart from others. “You can trust that they are going to do what you want. They've been running for over a year now and I have not needed to go to the site to look at anything, so that's a good sign that everything is just working,” says Andreas Ek.
