How it began
The Chaipattana low-speed surface aerator, Model RX-2, was invented by King Bhumibol Adulyadej. According to the secretary-general of the Chaipattana Foundation, quoted by The Nation, the king devised it after observing how polluted water in canals affected people, and directed the foundation to fund research on raising oxygen levels in water. A pilot model was first installed at Bowonniwet Wihan Temple. Thailand's Department of Intellectual Property granted the patent on February 2, 1993, which The Nation describes as the first patent granted to a reigning monarch.
How it works
The machine is a paddlewheel mounted on a floating buoy. Its scoops are trapezoid in shape so that they lift more water and increase the surface of water in contact with air. As the lifted water falls back, air bubbles are carried under the surface, and oxygen is absorbed faster. The National Research Council of Thailand states that the device can treat polluted water with a biochemical oxygen demand of 250 milligrams per liter at 600 cubic meters per day and cut that demand by more than 90 percent.
What changed first
The pilot worked well enough to lead to continued development and use in several areas. Because it floats, the aerator suits places where tidal water is polluted, and it can be installed as a fixed or a mobile unit. The research council put its running cost at 0.96 baht per cubic meter of water. Besides treating wastewater, it oxygenates ponds used for raising aquatic animals.
What lasted
The date of the patent, February 2, was made Thailand's Inventors' Day. In 2000 the Belgian Chamber of Inventors presented the king with a gold award for the aerator at the Eureka exhibition in Brussels, and a unit was later installed in a park in Brussels as a gift to Belgium. A second model, the RX-5, was patented in 2001.
Where it stands today
The Nation reports that the aerator is widely used in both the private and government sectors in Thailand. A review indexed on ResearchGate examines improvements to its performance and the development of a stand-alone solar-powered water wheel based on the design.
