Abstract
In order to clarify the puddled water by sedimentation, flocculation aids were tested by the flocculation test in a laboratory. Eight flocculation aids were selected to test among the soil amendment inputs and the feritilizers which contain relatively high percentage of calcium. They are considered to be used safely, because they are not special but are frequently used in usual farming. Among the eight flocculation aids tested, gypsum showed the most remarkable effect. The addition of 25kg/10a gypsum to the puddled water caused a rapid flocclation and clarified the water in a short time. The way of addition was also examined. A simple mixing method, spreading the gypsum on the puddled water and stirring them slowly for a short time, resulted a successful flocculation.
