On-line measurement of dissolved and gaseous hydrogen sulphide in anaerobic biogas reactors

• Published in: Applied microbiology and biotechnology 1995, Vol.43 (2), p.341-345
• Main Authors: MEYER-JENS, T, MATZ, G, MÄRKL, H
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biological treatment of waters; Biotechnology; Environment and pollution; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/BF00172836

The paper presented demonstrates the calibration of a silicone membrane probe for measurement of hydrogen sulphide in liquid and gas phase. The probe is connected to a quadrupole mass spectrometer as detector. The calibration of the probe results in linear calibration functions for different liquids and the gas phase. An example of the application of the measuring device for on-line measurement is reported for an experiment where sulphide is precipitated as iron sulphide by the addition of ferrous chloride. As a consequence of the addition of ferrous chloride, the concentration of H sub(2)S in the biogas rapidly decreases from 4.2% to 1.0% (by volume). The inhibition of the anaerobic treatment process is calculated on the basis of the reduction of dissolved total organic carbon before and during the experiment. The reduction of dissolved total organic carbon before the experiment starts is constant at 60%, rising to a maximum of 70% during the addition of FeCl sub(2). The difference in the conversion rate corresponds to an inhibition of about 14%. The gas production increases from 7.5 l l super(-1) day super(-1) to 8.5 l l super(-1) day super(-1). This inhibition observed before the addition of FeCl sub(2) is caused by 65 mg/l undissociated hydrogen sulphide in the liquid phase as calculated from the data obtained after precipitation of sulphide as zinc sulphide. The data show clearly that the conversion of acetic acid to methane is inhibited by dissolved H sub(2)S. The concentration of acetic acid drops sharply from about 25 mM to 15 mM after the FeCl sub(2) dosage has been started. The concentration of propionic acid decreases slightly from 12 mM to 9 mM. Most of the iron introduced during the experiment is immediately precipitated. The maximum concentration of dissolved iron measured in the effluent is 93 mg/l.