Author(s)

K. Fujisaki & M. Terashi

Abstract

The newly developed settler is an application of the lamella settler, which arranges inclined parallel plates in the vertical direction, contrary to the usual horizontal arrangement. In this method, the separated clear water is removed directly by suction from the top end of the parallel plates. For the removal of clear water, the right and left edges of the plates are closed, to make a tube with a rectangular cross section. These are the unique and original features of the equipment. Since each settling tube acts as a small settling tank, the treatment capacity is proportional to the number of settling tubes. Based on the results of the laboratory and on-site experiments, it is shown that the new tube settler system is very effective for the enhancement of settling tank performance. It is also shown from a numerical estimation that the settling tank installed with the new system has extremely high performance compared with the conventional settling tank. Keywords: settling tank, tube settler, lamella settler, overflow rates, treatment capacity. 1 Introduction In combined sewerage systems, storm waters often exceed the capacity of the treatment plant, which may cause environmental problems. To meet this problem, the enhancement of settling tank capacity is an important and urgent issue to the sewage treatment plant in the city. To improve the performance of the space limited settling tank, the lamella settler is widely used (for example, Takayanagi et al [1], Bridoux et al [2], Daligault et al [3], Kolisch and Schirmer [4]).

Keywords

settling tank, tube settler, lamella settler, overflow rates, treatment capacity.