According to United Press International, robotic "pigs" are constantly roving over German sewage plants. These electrical pigs, which look like child-sized Volkswagen Beetles, have only one task to perform: help dry the 60 million tons of sewage sludge produced every year in Germany alone. Using solar energy to dry mud, these robots are environmentally friendly and cost-effective. There are currently 100 of them in use around the world, and more are being installed every month. The manufacturer, Thermo-System, says:
Conventional drying processes burn up non-renewable energy, but Thermo-System harvests the sun's infinite resources to dry the mud. The sludge absorbs the heat from the solar rays, and an innovative ventilation system based on sensors and microprocessors keeps the air inside the shed warm and dry. In comes the electrical pig, a fully automated robot. With its mixing tools, it turns over and aerates the microbiologically highly active sludge and thus accelerates the drying process and helps prevent rotting. The whole system works fully automatically, uses up very little energy and can be easily maintained.
Here's a photo of the robot at work:
For more information about these technologies, here is a link to a description of the Electric Mole (PDF format).