Application
RITTER has developed a CO₂ absorption bottle which reliably absorbs more than 99% of CO₂ from biogas. Guaranteed! Without any indicator liquid for absorption limit! This absorption bottle combined with the »RITTER Biogas Batch Fermentation System« provides the ideal solution for professional biogas research.
Operating Principle
The biogas generated in the fermentation bottles flows through a dip pipe into the absorption bottle (“bubbler”) containing the absorption solution. Due to the unique dip pipe design RITTER guarantees a CO₂ absorption rate of at least 99% up to reaching the absorption capacity limit. This capacity limit will be indicated by the MilliGascounter by measuring the volume of methane remaining in the gas stream after absorbing the CO₂.
The high CO₂ absorption rate is achieved as a result of …
Due to this design, the absorption capacity of the RITTER CO₂ absorption bottle is far superior to that of absorption bottles with surface absorption as the following diagram shows:

Technical Specifications
Dimensions absorption bottle (»bubbler«) | Volume 250 ml Wide mouth GL80 with screw cap ø D 95 mm x H 106 mm |
Material | Borosilicate glass |
Dip pipe chamber volume | 8.3 ml |
Holding time of CO₂ bubble in dip pipe chamber | dependent on gas flow rate |
Absorption solution | 3-molar caustic potash solution (KOH 3 mol/ltr in aqua dest.) |
Gas in/outlet ports | PVDF screw-type tube connection for tube Ø 4i / 6o mm |

Absorption Capacity
Definition:
The absorption capacity is the volume of CO₂ which is absorbed until the absorption rate is decreased from 100% at start of absorption process to 99%. When the limit of absorption capacity is reached, the gas at the absorption bottle outlet contains 1% of CO₂.
Table of absorption capacities at various flow rates and CO₂ concentrations: (1)
Biogas Input | Flow Rate (ml/h) | ||||||||
---|---|---|---|---|---|---|---|---|---|
0 | 50 | 100 | 200 | 300 | 500 | 750 | 1000 | ||
CO₂ absorption capacity, approx. (ltr) (2) | 40% CO₂ / 60% CH₄ | 17.0 | 13.4 | 12.1 | 8.8 | 7.9 | 7.8 | 7.7 | 7.6 |
60% CO₂ / 40% CH₄ | 17.0 | 13.5 | 11.8 | 8.9 | 8.5 | 8.3 | 8.0 | 8.1 | |
Max. volume of methane, approx. (ltr) (3) | 40% CO₂ / 60% CH₄ | 25.5 | 20.1 | 18.2 | 13.2 | 11.9 | 11.7 | 11.6 | 11.4 |
60% CO₂ / 40% CH₄ | 11.3 | 9.0 | 7.9 | 5.9 | 5.7 | 5.5 | 5.3 | 5.4 |
(1) This table will be updated with additional CO₂ concentration values when new data becomes available. For determination of CO₂ concentration values the RITTER »MultiGas« Sensors are recommended. With the RITTER »MultiGas« Sensor duo IR2, the concentration values for both Methane and CO₂ can be determined simultaneously. If no determination of the CO₂ concentration value is possible, it is recommended to use the smallest amount of CO₂ concentrations stated in the above table.
(2) Per bottle filling 250 ml, absorption solution KOH 3 mol
(3) After the CO₂ was absorbed from the biogas, the MilliGascounter displays the volume of the pure methane. The CO₂ absorption capacity limit is reached when the MilliGascounter indicates the values the stated in the table above.
Please note: The values for the max. volume of methane stated at a specific flow rate were obtained at a constant flow rate of biogas. However, with biogas fermentation processes the flow rate varies in general significantly during a fermentation test run. In order to get a more meaningful value for the remaining CO₂ absorption capacity the use of the data acquisition software »RIGAMO« is highly recommended.
Calculation of Absorption Capacity with Data Acquisition Software »RIGAMO«
The table above shows that the absorption capacity with the RITTER absorption bottle …
The following diagram shows the CO₂ absorption capacity as a function of the flow rate:

Features of the software:
V 2.1 / Rev. 2024-07-03 / Subject to alterations.
https://www.ritter.de/en/data-sheets/co%E2%82%82-absorption-bottle/
Dr.-Ing. RITTER Apparatebau GmbH & Co. KG · Coloniastrasse 19-23 · D-44892 Bochum · Germany
For questions please contact mailbox@ritter.de or your local distribution partner (on our overview page)