As part of the upcoming Aqua Metropolis festival in Osaka, engineering firm NTT Facilities has developed a pair of solar-powered, UFO-shaped floating water purifiers that will be deployed in the city’s canals and in the moat at Osaka Castle. (as reported in pnktentacle.com)
These appear to be solar powered units which float in the canals and pump oxygenated water down into the deeper parts of the canals.