298 94 307/02 Untersuchungen zum Stand der Umsetzung des ...

BSB5 – load Bd (BSB )
NH4 -N – load Bd (NH - N)
COD: N
BSB5 – volume load BR (BSB )
N – volume load BR (N)
BSB5 – sludge load BTS (BSB )
N – sludge load BTS (N)
Excess sludge incidence TSÜS
Age of sludge tTS
Specific O2 consumption (BSB5) OVC
Specific O2 consumption (N) OVN
Flow of return sludge QRS
Teil 3 Seite 4-42
346 kg/d
90 kg/d
5,6 : 1
0,19 kg/(m 3 ·d)
0,05 kg/(m 3 ·d)
0,05 kg/(kg·d)
0,015 kg/(kg·d)
66 kg/d
95 d
2,09 kg O2/ kg BSB5
1,91 kg O2/ kg BSB5
43%
The entry of air and the circulation of the biomass takes place by means eight aerator
chains. The aerator chains consist of 7 floating aerators each, connected to one another
by means of air supply hoses. The air is introduced in the form of small bubbles through
aerator "candles" (Friox system) suspended over the basin floor. The required quantity of
air is made available through sliding vane rotary compressors. A compressor constantly
runs on base load in order to ensure a specific minimum level of circulation of the acti-
vated sludge. The connection of further compressors is regulated by a superordinate tim-
ing programme and an automatic O2/Redox control.
Through the time interval control, one or more chains are deliberately targeted more
strongly with air than the others. Through the intensive aeration of the non-throttled chains
the formation of oxic zones occurs there, whereas at the throttled chains the formation of
anoxic zones takes place. After a settable running time, the control ensures a change-
over of throttled chains. In this way, the oxic zones migrate throughout the entire basin.
The demand for oxygen is regulated through O2/redox control, in which process the re-
dox measurement supplements the oxygen measurement downwards. Through the redox
measurement, the necessary information for the control of the de-nitrification in the anoxic
range is obtained.
For the purposes of nutrient equalisation or increasing oxygen capacity, the plant is
equipped with the necessary dosage stations. The separation of the biomass/effluent mix-
ture takes place by means of buoyant final treatment. The off-flow of the final treatment
plant is then also channelled through an aerated pond before it is channelled into a bio-
trench through a further sedimentation zone.
The official investigation yielded the results outlined in Table 4-12 for the period 1992 to
1996 These allow the conclusion that the plant would have fully complied with the regula-
tions applicable at the time.