Abstract
As domestic waste water becomes the high density, treatment of waste water using septic
tank gradually became difficult. Therefore, we showed a newly pretreatment unit (Mashiko-Clean
type III) for septic tank. This characteristic of this unit is a bubble column type aerator of three
towers, and it has strong aerating system. In this paper, we evaluated an ability of waste water
treatment from various parameters with water analysis. As a result, this unit has degradability of
carbon compounds in simulation waste water. COD and BOD were always less than a discharge
lower limit value. On the other hand, there was not an anaerobic space, this unit could not removal
nitrogen (nitrite nitrogen) and phosphorus compounds. To give the performance of this unit
conventionally, we must improve setting (or auditioning) of the anaerobic areas and circulation function between the towers.
