Joint International Conference on Long-term Experiments ...

The effluent from the anaerobe reactors flows due to gravity towards the tank where the
aerobe purification of the anaerobe pre-treated water takes place. A smaller flow will be
recirculated towards the correction tank through a recirculation pipe.
The percolating filters existent before the plant was extended will be used as
aeration tanks. When the biofilter is filled up to a height of 5,1 m (the tank’s volume is
770 m 3 ), o decrease of BOD is produced for an anaerobe productivity of 80% of: 0,71
kg BOD / m 3 . The four aeration tanks are used in a series configuration.
The anaerobe effluent will flow together with the recirculation course of the sludge
decanters in the first aeration compartment, passing then through all the four
compartments. The dissolved oxygen will be measured with the help of a measuring
device placed in the third and forth aeration compartment. The aeration is achieved with
the help of a bubble aeration system, supplied by two bellows, the retention type being
2,9 hours. The tank is aerated with a capacity of 334 Nm 3 /h.
At the forth compartment outlet of aerobe treatment, a sludge/effluent separation is
achieved with the help of sludge decanters, with a total area of 226 m 2 .
The sludge resulted after the purification should be processed by thickening, as a
result the thickened sludge is separated and the excess water from the sludge thickener
will flow in the pH correcting tank.
The decanted effluent has the following parameters: Flow: 86 m 3 /h
BOD: 82 mg/l
TSS: 158 mg/l
pH : 6,5 – 8,5
temperature: < 30 o C
Figure 1. The scheme of the technological process
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