To clean up the highly polluted Makasan swamp, the King developed an inexpensive natural filter relying on water hyacinths, which have a great capacity to absorb wastes. After absorbing pollutants the saturated plants are detoxified and used as fuel, compost and material for making baskets and place mats for poor people who live around the swamp. He also introduced paddle-wheel-like devices that aerate the water in the stagnant pools of Bangkok's Bavornnives Temple. Fish have returned to Makasan swamp and turtles once again occupy the pools of Bavornnives Temple.