Page 256 - Industrial Wastewater Treatment, Recycling and Reuse

230 Industrial Wastewater Treatment, Recycling, and Reuse

B. Bayer AG, Brunsbuttel Works (Germany)
Following several years of experience with the 8 m-high biotanks, the sec-
ond phase of construction was completed in 1979. Six tanks then went into
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operation ( 10 15 m, volume 1200 m ) having a total volume of 7200 m ;
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these carry out the biological purification of 5600 m /day of waste water
with a BOD 5 load of 4.2 t/day. This requires an O 2 uptake of 7.2 t/day.
The secondary clarifiers (sedimentation funnels) are situated between the
tower and are also covered.
C. Bayer Factory at Thane (India) (not in operation from year 2007)
Tower Biology in concrete towers (2 tanks of 15 17 m, water level 15 m)
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with adjacent sedimentation funnels. Wastewater throughput 3600 m /day
with a BOD 5 load of 2 t/day; O 2 uptake 4 t/day. This treatment plant com-
menced operation in 1981.
D. Konigsbacher Brewery, Koblenz (Germany)
One of the main reasons for the choice of Tower Biology in this case
was the lack of space available. The treatment plant consists of a
tower ( 20 20 m) with an adjacent funnel-shaped secondary clarifier.
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2000 m /day of effluent are treated; the BOD 5 load is 3 t/day. O 2 uptake
is 4.2 t/day. The organisms’ one-sided diet (carbohydrates) encourages the
formation of filamentous activated sludge, which tends to rise to the surface
during de-aeration of the Tower Biology outlet. To deal with this, a new
type of flotation unit was installed, consisting of a single flotation cell
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(D¼2.5 m; V¼3m ) with a funnel-shaped nozzle (induced air flotation).
This gives a recycled sludge with about 10 g/L dry matter and a water-clear
outflow of the purified wastewater. The Tower Biology went onstream
in 1981.
E. Petrochemical Plant in Wesseling, North Rhine–Westphalia (Germany)
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Here, there is 8000 m of wastewater to be treated daily, containing an
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ammonium (NH 4 )loadof8 t/dayaswellasBOD 5 load of 6 t/day. Nitri-
fication and denitrification processes therefore have to be integrated into
the biological treatment for purposes of nitrogen elimination. Following
extensive trials on a semi-technical scale, the industrial-scale plant shown
in the sketch in Figure 5.13 was designed. The plant comprises a two-step
nitrification, the first step also incorporating the aerobic oxidation of car-
bon as well as 70% nitrification (from 800–1000 ppm to 100–150 ppm).
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In the second step, the remaining NH 4 is degraded to 5–30 ppm. The
nitrites and nitrates thus formed then have to be reduced to nitrogen with
the aid of hydrogen donors (e.g., methanol). To save on methanol, the
outflow from the second nitrification step is divided into two streams;