Updated: July 2002

1. Outline

For the purpose of biologically removing nitrogen and phosphorus, the anaerobic-deoxidizing-aerobic method has been used. This method, however, has the disadvantage that the reactor tank needs about double of the volume comparing with conventional activated sludge process.
We have developed an epoch-making system called "BIOERG" which removes nitrogen and phosphorus simultaneously with a reactor tank capacity usually used in the conventional activated sludge process by feeding carriers that adsorb and fix microorganisms in the aerobic tank inside the reactor tank to increase the microbial density.

2. Features

The BIOERG provide the following features:
1) High Treatment Capability in Reactor Tank
The adoption of the carrier-borne anaerobic-deoxidizing-aerobic method enables simultaneous biological removal of nitrogen and phosphorus in the secondary treatment process.
2) Biological Treatment Process employing Carriers that adsorb and fix Microbes
The carriers which adsorb and fix microorganisms significantly accelerate and stabilize the nitrification process.
3) Reduction of Treatment Time by Half
4) High Purification Performance
From ordinary sewage, for example, highly purified water which includes less than 10 mg/l of BOD, 10mg/l of T-N and 0.5mg/l of T-P can be obtained.
5) Adoption of submersible Aerator
An improved submersible aerator is used to distribute the carriers in the aerobic tank and enable energy saving operation.
6) Separation of Carriers by Special Screen
At the outlet of the aerobic tank a special screen is placed. This enables easy separation of carriers without clogging.
7) Easy Application to existing Facilities

3. Performance

In terms of removing eutrophic salt contents the following features can be realized.
1) Nitrogen Removal Rate
60 - 80% of T-N can be removed.
2) Phosphorus Removal Rate
70 - 90% of T-P can be removed

4. Areas of Application

The BIOERG may be applied to various kinds of wastewater treatment plants. Examples include treatment facilities for a wide range of substances, such as sewage, waste water from exhaust gas scrubber, contaminated water from waste landfill sites, etc

5. Special Features of Carriers

The carriers are made of hydrophilic gel comprising polymers which mainly consist of polyethylene glycol and are formed into pellets 3-5mm in diameter having a specific gravity of 1.02.
The BIOERG carriers provide the following features:
1) The carriers are based on an improved form of biological membrane technology and are highly practical.
2) Such carriers are easy to produce in large quantities and provide excellent physicochemical resistance.
3) The specific gravity can be arbitrarily set in the range from 0.95 to 1.10. Since the carriers are hydrophilic, they are suitable for multiplication of microorganisms.
4) Pellets can be manufactured in uniform diameters (3, 4, 5mm), allowing easy handling.
5) The compression strength is higher than 1.5 - 2.0 MPa (15 - 20kg/cm²) on average.
6) No need of additional operation to fix sludge which contains microbial germs.