Updated: July 2002

1. Purpose

The BIOPAC is a fixed bed type aerobic biological wastewater treatment system which has high removal ability of SS, COD, BOD or ammonium from the wastewater and performs both biological treatment and filtration. Therefore the BIOPAC is widely applied such as to organic wastewater treatment, sewage secondary treatment, advanced treatment and purification of lakes, marshes or rivers water.
The BIOPAC is similar to the sand filtration system in its feature and flow system.
Raw water flows in from the top of the BIOPAC and goes downward through the granular media and outflows from the discharge pipe located at the bottom.
The air is supplied to the microorganisms attached on the granular media from the bottom of the BIOPAC and the counter-current between air and water realizes the high oxygen dissolving efficiency and effective decomposition of organic substances and nitrification.

2. Performance

BOD removal rate: 80 to 95%
Installation area: 1/10 to 1/6 of that of activated sludge process or contact aeration process
Specific Surface Area (Microbial attached area per reactor volume): 5 times that of contact aeration process or rotating biological contactor
Power consumption: less than ½ of that of activated sludge process or contact aeration process

3. Advantages

(1) High oxygen transfer efficiency of the BIOPAC can reduce blower power up to ½ of that of ordinary biological treatment process and also realizes a high loading treatment.
(2) Since the BIOPAC has the filtration function, the sedimentation basin in a later stage can be dispensed with and as a result, installation area can be reduced.
(3) The BIOPAC does not have operational parameters such as SRT or DO. The optimized back-washing system prevents clogging of the filled media and is operated automatically.
(4) High dense microorganisms held in the fixed bed and high filtration efficiency of the microbial attached media makes the system stable against the load fluctuation.