Rütgers Deutschland GmbH submerged aerated fixed bed system
Task
The company Rütgers Deutschland GmbH produces diverse aromatic
compounds at its site in Castrop-Rauxel; for which tar oils constitute
the raw materials. The fixed bed facility serves the biological pre-treatment
of the waste water from the distillation and subsequent treatment of these tar oils.
Solution
For the pre-treatment of the waste water the immersed, ventilated fixed bed process was chosen, as the full advantages of this process become particularly apparent with waste water that is difficult to treat.
The construction of the plant was based on the following loads:
| Inflow for pre-treatment |
1,250,000 m³/p.a. |
| COD freight |
1,600 tonnes/p.a. |
| Nitric freight |
175 tonnes/p.a. |
The designing of the biological cleaning treatment was based on pilot tests.
System technology
For the large-scale construction of the plant, a fixed bed facility was chosen, comprising 12 cascades with a total volume of 4,000 m³ filling material. The cascades for carbon and nitrogen decomposition are separated by an intermediate waste water treatment in order to increase the efficiency of the nitrification.
A BIO-NET® with a specific surface area of 150 m²/m³, which was especially developed for this plant, was used as filling material.
The BIO-NET® is mounted on a stainless steel support grate by means of connecting rods. The ventilation is effected through ceramic ventilation pipes.
Discharge values
The discharge values from the plant for COD are 90% with an average surface load of 14.5 g/m²*d. 90% was also achieved for the elimination of nitrogen, with a surface load averaging 2.1 g/m²*d. With these discharge values, the plant exceeds what was expected of it.
Kriebethal medium-load trickling filter
Task
The Kriebethal sewage treatment plant has a plant size of 45,000 PE.
The wastewater to be treated primarily comes from the local paper mill and is biologically treated along with communal wastewater and excrement. In order to meet current requirements, the plant was converted to enable the complete removal of nitrogen.
Solution
Follow the primary treatment phase, the treatment plant is designed as a two-line, two-stage system. The first stage comprises two trickling filters that are operated in parallel and must achieve a treatment efficiency of at least 45% at a maximum volumetric load of 2 kg BSB5/(m³d). Without intermediate treatment, the trickling filter discharge including the excess sludge is fed into a downstream conventional activation unit with a three-stage cascade design.
System technology
Both trickling filters are equipped with SESSIL® support material. This trickling filter material consists of film strips that are suspended from a supporting grid beneath the water distribution element.
Technical data for trickling filters:
| Volume |
V = 1.610 m³ |
| Fill level |
h = 6,0 m |
| Diameter |
D = 18,50 m |
Specific surface of SESSIL®
|
Aspez= 100 m²/m³ |
Discharge values
The plant operator confirms that the performance of the trickling filters is excellent. Despite considerable intake fluctuations, the treatment efficiency has remained stable at 63%, which is significantly more than the required treatment performance.
Leudelsbach denitrification trickling filters
Task
The plant operator confirms that the performance of the trickling filters is excellent. Despite considerable intake fluctuations, the treatment efficiency has remained stable at 63%, which is significantly more than the required treatment performance.
Solution
The procedural design of the plant was based on scientific research carried out by the University of Stuttgart. Two denitrification trickling filters are now operated in parallel in order to effect the targeted removal of nitrogen. The trickling filters are also covered with GRP domes.
In order to avoid hampering the performance of the nitrification process, which also takes place in a trickling filter plant, the excess sludge from the denitrification plant is separated be means of an intermediate treatment.
System technology
Both denitrification trickling filters were fitted with the trickling filter variant of the SESSIL® support material.
Technical data for the denitrification trickling filters:
| Volume |
V = 1.445 m³ |
| Fill level |
h = 4,6 m |
| Diameter |
D = 20,00 m |
Specific area of installed material
|
Aspez= 120 m²/m³ |
Discharge values
Carbon decomposition with the following limit values:
CSB = 90 mg/l
BSB5 = 20 mg/l