The OD process is a low-load activated sludge
process for wastewater treatment.
Mechanical aeration equipment is not only for providing oxygen
necessary for
treatment but also for circulating activated sludge within the
oxidation ditch
without letting it settle down.
Features of the OD Process
1)
Easy to operate and manage.
2)
Possible to remove organic matters and nitrogen constantly
in spite of
chronological changes in the quality and quantity of wastewater
influent.
3)
The sludge generation volume will be reduced as compared
with the conventional activated sludge process.
What is the Advanced Oxidation Ditch Process?
The OD process can constantly deal with influent
load changes and advanced wastewater treatment by introducing
the Aerobic Solid Retention Time Control or ASRT Control. With
this process, it is possible to remove organic matters and nitrogen
constantly as it reduces the Operation and Maintenance costs
without conducting unnecessary aeration.
Nitrogen removal by ASRT Control
In facilities with the treatment flow as shown
below, it is possible to achieve the nitrogen removal rate of
more than 85% through operation and management based upon the
ASRT Control.
Conducting accurate ASRT Control according to
the fluctuation of the influent volume.
Achieving the nitrogen removal rate of over 85%
by operating at
Aerobic Agitation Time : Anoxic Agitation Time =
1:1 in the case of the design maximum daily influent
flow.
Flow
Sheet of the OD process utilizing ASRT Control (An example of operation and management
facilitated by direct sludge withdrawal from the OD)
The ASRT Control is the following
control to secure the minimum ASRT required for keeping
nitrifying bacteria, irrespective of the fluctuation of
the influent volume:
1)
In order for the system to keep a sufficient amount
of nitrifying bacteria and
other microorganisms required in the case of high
loading, it increases /
reduces the sludge withdrawal volume according to
the influent load.
2)
To prevent the death or inactivation of microorganisms,
it controls aeration
time according to the influent load.
