| 摘要 |
<p>PURPOSE:To remove colloidal components in night soil and to reduce foaming by subjecting the night soil and the sludge subjected to a secondary treatment to solid-liquid sepn. after mixing and agitating, subjecting the supernatant liquid thereof to the secondary treatment then to the solid-liquid sepn. and returning part of the settled sludge. CONSTITUTION:Night soil is introduced together with the sludge which is settled in a secondary treatment and is returned from a settling tank 5 into a mixing and agitating tank 1, where the colloidal parts which are frothing substrates are adsorbed on the sludge. The liquid mixture in the tank 1 is introduced into a settling tank 2 where the same is subjected to solid-liquid sepn., whereby the mixture is separated to an upper layer part and a lower layer part. The supernatant liquid in said upper layer part is supplied to a secondary treating tank 4 performing essentially of an aerating treatment for the purpose of the secondary treatment. The colloidal components in the night soil are already removed by the treatments thus far and the frothing is decreased considerably. The secondarily treated liquid from the part 4 is supplied to the tank 5 where the liquid is subjected to solid-liquid sepn., and part of the precipitate of the secondary treatment is returned as the sludge of the secondary treatment to the tank 1.</p> |
