Abstract
Removal efficiency of a new equipment for treating gray water was analysed from the test results reported in the previous paper. Amounts of pollutants of the raw water, the pretreated water in the first tank and the treated water from the second tank were calculated by integration of the relationships between flow volume and water quality. The mean removal efficiency of the amounts of BOD, COD, SS, TOC and MBAS were 82, 74, 62, 64 and 83% respectively. Solid in the screening net and sediment in the first tank were also investigated in detail. The solid in the screening net increased about 1.8 wet-kg (0.2 dry-kg) in the first month but only 6 wet-kg at six monthes because of biodegradation. The volume of sediment in the first tank approached to the small constant values of 20-60 l.Wherefore, the sediment need to remove only once a year or two years. The typical carbon balance and microorganisms in the second tank were also discussed. From the above results, an improved equipment was designed and put into practical use.
