As a new sludge reduction technology with a phosphorus removal mechanism, a vibration milling technology that uses iron balls have been applied to the wastewater treatment process. Three anaerobic–aerobic cyclic activated sludge processes: one without sludge disintegration; one disintegrated sludge by ozonation; and the other disintegrated sludge with the vibrating ball mill were compared. Ozonation achieved the best sludge reduction performance, but milling had the best phosphorus removal. This is because iron was mixed into the wastewater treatment tank due to abrasion of the iron balls, leading to settling of iron phosphates. Thus, the simple means of using iron balls as the medium in a vibrating ball mill can achieve both a sludge reduction of half and excellent phosphorus removal. Material balances in the processes were calculated and it was found that carbon components in disintegrated sludge were more resistant to biological treatment than nitrogen.
Keywords: activated sludge, disintegration, excess sludge, phosphorus removal, vibration milling, wastewater treatment