The treatment of sewage

摘要

Raw sewage enters through pipe 10 and passes through a suitable grit chamber 11. If a primary settler is used in connection with this process, grit chamber overflow enters the primary settler and the overflow from the primary settler flows into an aeration tank 15 fitted with swing diffusers 16. Grit chamber effluent enters the tank 15 through a pipe 14, and is mixed with return sludge which is recirculated into the system from a splitter tank 24. After a period in the aerator the aerated mixed liquor overflows through a pipe 17 to a settling tank 18 where the suspended solids in the mixed liquor precipitate to form a sludge and clear effluent is discharged from the settling tank through conduit 19. Sludge accumulated in the bottom of the settling tank 18 is moved to a sump 21 by means of a scraper 22. Sludge is removed from the sump 21 by means of a conduit 23 and is conducted to a proportioning or splitter tank 24 by a pump 25 and a conduit 26. The proportioning tank 24 is provided with an adjustable proportioning weir 27 adapted to make a suitable split in the flows to recirculation and waste disposal. The loading rate of sewage, aeration volume, recycle waste sludge and recycle to incoming sewage ratios are specified. Specifications 885,602 and 885,603 are referred to.