| Long term persistent turbidity is a major problem in reservoirs of Japan and other countries. We are examining the practical methods using natural coagulants, such as allophane (clay), which can be deposited in the reservoirs, to prove experimentally the effectiveness of allophanes coagulation performance, and to develop a useful and environmental friendly coagulation method for turbid water. The experiments conducted in this study provided two important findings. The first is that, through the laboratory experiments, we proved that the new practical dispersers, which are a cavitation mixer and a high pressure water sprayer, can be used effectively to disperse allophane. And we confirmed the usage of these dispersers raises the zeta potential of allophane. This effect is presumed to promote coagulation. The second is that the coagulation effect at the depth of more than 10 m was confirmed through the field experiment, where the new dispersers were used. As mentioned above, we can propose more practical, useful, and environmental friendly treatment method for turbid water using allophane at dam reservoirs. |
