1Department of Ocean Science, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, 2TOYO Construction Co. Ltd. Environmental Engineering Department, Chiyoda, Tokyo 101-8463, 3Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 405-8572, 4Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan
Sea algal paste was obtained by soaking brown alga in sodium carbonate solution and was found to have a flocculating effect on muddy water in the presence of calcium chloride as a cross linking agent. This technique does not involve the extraction of alginic acid and production of secondary waste. The sea alga paste obtained by soaking in sodium carbonate solution for five minutes at 70°C demonstrated an excellent flocculating effect, which did not depend on the density of muddy water. Stirring time after mixing all ingredients was found to affect the flocculation. Furthermore, the amount of sea alga paste and calcium chloride also influenced the coagulating effect.