Updated: July 2002

1. Outline of system

Attached growth type bio-reactor is a system to treat BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand) and nitrogen contained in various waste water in a faster and more efficient way than conventional and standard activated sludge process.
(1) Faster treatment enables it to economize space.
(2) Rotary atomizer enables it to save power.
(3) The treatment capacity of existing aeration tank can be increased easily.
(4) Tough to bulking
(5) Tough to the load fluctuations of raw water

2. Characteristics

1) High-speed Treatment
By feeding the carrier into the aeration tank and by retaining the activated sludge on the carrier in high density, volumetric load, which is the treatment speed of living thing, can be set to higher levels. Therefore, the aeration tank can be designed more compact.
2) Power-saving
The rotary atomizer improves oxygen dissolution efficiency by dissolving air into the water mechanically (3 times as compared with the conventional diffuser tube type). Since only one-third or so of air is required, blower of smaller capacity may be used, thus reducing power consumption.
3) Treatment capacity of existing aeration tank can be increased easily.
Only by feeding the carrier into existing aeration tank, the concentration of activated sludge in the aeration tank can be set to higher levels. Therefore, the treatment capacity of existing aeration tank can be increased easily. The rotary atomizer further improves the system efficiencies.
4) Tough to Bulking
Activated sludge is retained on the carrier in high density. Therefore, the process is tough to bulking.
5) Tough to Load Fluctuations of Raw Water
Since the concentration of the activated sludge in the aeration tank can be set to higher levels, load increase of the raw water can be followed.

3. Performance

Performance Comparison with Conventional Type (result of case study)
Flow rate of treated water: 1000 m³/d
BOD concentration: 2000 mg/l

Fig.1 Attached growth type bio-reactor