22.02.06 | Siemens has installed an automatic water purification system in the polar bear exhibit at the Nuremberg Zoo. The system ensures that the big carnivores will enjoy the most natural conditions possible — all year long. Leaves and twigs, pollen and trash discarded by visitors — there’s always something to be filtered or fished out of the bears’ outdoor pool which covers 600 square meters. The three full-grown polar bears that live here, however, make this work too dangerous for maintenance personnel. That’s why the job will be handled by a control system from Siemens. At first it will be used to control the water treatment facility, but it can be expanded if desired to control all of the zoo’s technical units, which would give Nuremberg an automated high-tech zoo.

And the new automated system will be virtually invisible to visitors. For the public, a geyser that gushes up between the rocks at intervals and a waterfall are the technology’s only visible features. Treatment of the pool is controlled by the Simatic system. There are several treatment cycles for the various purification processes. Pumps draw cans and containers into special discharge points on the floor of the pool, leaves and twigs are sucked into outlets just beneath the water’s surface, and pollen is filtered out with a large strainer on the pool’s inside wall. The system recirculates 1,200 cubic meters of water a day.

Until recently the zoo had used a number of pumps to do the work, each controlled by its own system. The new treatment facility uses a single system with five pumps, which cuts costs and boosts efficiency. The Simatic control system handles the fine-tuned coordination of the pumps. When lots of leaves are accumulating in the fall, for example, the control system draws more water from the surface than in summer, and it recirculates more water during cold weather to prevent ice from forming.

The control system is a particularly effective energy-saver thanks to its frequency converters, which ensure that the pump motors don’t run all the time at a constant speed. The converters adjust the motor speed, and thus the pumps’ performance, to the workload at hand. This reduces the electricity needed to operate a pump by between 30 and 50 percent.