水質浄化技術におけるDO改善性能評価方法について

DO improvement performance evaluation for water purification technology

Creators Hadano Kesayoshi

Creators Ohgi Kyo

Creators Ma Jun

Creators Asai Koji

Creators Nakano Yoishi

Creators Fujisato Tetsuhiko

In order to improve the DO condition of a lake or sea, authors are developing the liquid film gas dissolution technique. This paper presents a summary of this technique, experimental results of DO improvement, and performance evaluation method for the DO improvement considering the DO concentration of the water to be treated. This DO improvement method transforms the water into bubble clusters which essentially makes water elements of the thin film of bubbles. This method yields a large value of the dissolved gas concentration gradient in the water and therefore attains an efficient gas dissolution. Also, this method treats deep water utilizing the airlift effect by aeration in the shallow part of the pipe, thus saving energy. The authors have shown experimentally that the DO increment depends on the DO concentration of the water to be treated, and proposed the equivalent DO increment as an index of the DO increment which can be used irrespective of the DO concentration to be treated and which indicates the potential of the DO increment for the same working condition from the theory of the aeration device. The validity of this index was checked using the result of the present experiments.