Water treatment using filters, aerators, return of treated water and backwashing

摘要

Wastewater treatment apparatus comprising upper 62 and lower 33 chambers separated by a plate 32. A filter layer 50 is supported on the plate 32. Aerators 42 over the plate 32 supply process air to the filter medium 50. Treated water is discharged 48 and returned 57 to the lower chamber 33. The apparatus has an outlet 60 for drawing off water and sludge in the lower chamber 33 before backwashing, means 40 for introducing waste water into the lower chamber 33, pipes 35, 44 for supplying the aerators 42, means for supplying backwashing air 34 and water 41 into the lower chamber 33 and nozzles 46 extending through the plate. The batch style treatment uses repeated aerobic and optionally anaerobic biological filtering processes. The process removes organic matter, suspended solids, nitrogen and phosphorous.