 Type
of Plant
The plant works as a sequential batch reactor (SBR). Pollutants
from the wastewater are absorbed by the activated sludge and
converted into biomass. The micro-organisms are activated
by the oxygen intake during the aeration period. The process
employs a four-stage cycle: fill, react, settle and empty.
The SBR process is time-based rather than flow-based so there
is much more control of the treatment process.
How does it work
The domestic wastewater is introduced into the first primary
treatment chamber. This serves as storage for primary and
surplus sludge and as a buffer for the inflow. The nominal
BOD5-load of the biological treatment basin is 60 g BOD5/
(PE*d). From first chamber, wastewater flows by gravity to
the second primary treatment chamber. From the second primary
settlement chamber, the retained waste water is transmitted
to the biological treatment chamber via a siphon pipe. The
wastewater is agitated with pump. Anoxic conditions are created.
Commencing the denitrification process. The wastewater is
aerated causing the nitrification process. During the aeration
period the surplus sludge is returned to the first chamber.
In this way, the sludge content of approximately 400 ml/l
is maintained. These activities take approximately 2 hours
and are repeated 3 times during the cycle. The full cycle
takes approximately 6 hours. After that sedimentation takes
place. During that period, aeration and agitation are turned
off, so that the activated sludge sinks to the bottom of the
activation chamber until only purified water remains in the
chamber’s upper area. After two hours of settlement,
the clear water is pumped out. Approximately eight hours after
commencement, the cycle comes to an end and another cycle
recommences. |
