Development of Water Pollution Control System for Urban Lakes using Algae Trap

漂浮的藻类，被称为水华，由于它们的外观不美观，并且在分解时释放出有毒的味道和气味，在湖泊和其他蓄水池中造成了滋扰。这被称为富营养化造成的水污染。目前存在一些方法，如使用铜离子，但它们会造成大量鱼类死亡等二次水污染。我们开发了一种名为“藻类陷阱”的收获系统。它由堰作为入口和分离罐作为出口组成。浮藻是由风聚集而成的。将捕集器设置在背风的岸边，可以在没有任何能量的情况下高密度捕获它们，因为它们被漫天的波浪带入捕集器，然后在分离池中通过自动漂浮将它们与水分离。我们进行了诱捕的现场实验和模型实验。现场试验结果表明，该系统能以较低的成本有效地收集水华。非常有趣的是，模型实验的结果表明，流入陷阱的漂浮粒子是势分析预测的数倍。对SMAC方法进行改进，求解带有表面张力的navierstorks方程。分析表明，马兰戈尼效应加速了颗粒的流动。通过测量水华的垂直迁移速度来设计分离池。然后测量再浮藻的密度，以了解分离效率。测定了藻类的比过滤阻力。这些结果表明，藻类很容易从水中分离出来，但可能需要进行预处理，过滤再浮藻以回收资源。

Accumulations of floating algae, known as water-blooms, cause nuisances in lakes and other water impoundments because of their unsightly appearances and the release of noxious taste and odors as they decompose. This is called water pollution by eutrophication. A few methods exist such as application of copper ions, but they cause secondary water pollutions like massive fish-kills.We developed a harvesting system named algae trap. It consists of a weir as an inlet and a separation tank with outlet. Floating algae are accumulated by wind. By setting the trap on the lee-ward shore, we can harvest them in high density without any energy because they are carried into the trap by overtopping wave and then separated from water in separation tank by autofloatation.We carried out on-site and model experiments on trapping. The results of onsite experiments show the system can harvest water-blooms effectively at low cost.It is very interesting that the result of model experiments showed that floating particles flowed into the trap as several times much as ones predicted by potential analysis. The SMAC method was modified to solve navierstorks equation with the surface tension. This analysis showed that marangoni effect acceralated the particle flow.Vertical migration speeds of water-blooms were measured to design the separation tank. After that densities of reflaoted algae were measured to know the efficiency of separation. Specific filtration resistances of algae were also measured. These results show that it is easy to separate algae from water but some pre-treatment may be need to filtrate refloated algae for resources recovery.