Simplified Experiments on the Changes of Water Quality Made Using Tofu to Understand the Phenomena of Water Pollution and Eutrophication in Environmental Education

In this study, the authors propose simplified model experiments which show the phenomena of water pollution in rivers and closed bodies of water and of eutrophication in closed bodies of water, using a piece of tofu and two cups of clean water. Tofu is used to representative of organic matter. The water without organic matter (tofu) in the cup remains clear forever, but the water containing a piece of tofu in the cup gradually becomes polluted in a few days. The water containing a piece of tofu is polluted with phytoplankton, and becomes green in two to three weeks which shows the phenomenon of eutrophication. In this study, the authors explained the phenomena of water pollution and eutrophication which occur in the cup by analyzing water quality using transparency, pH, BOD, SS, T-N, T-P and chl-a. The simplified model experiments proposed in this study are very useful for the environmental education at primary and junior high schools.