Monitoring toxicity in anaerobic digesters by the rantox biosensor: Theoretical background
✍ Scribed by Alberto Rozzi; Maria C. Tomei; Appio C. Di Pinto; Nicola Limoni
- Book ID
- 101242431
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 112 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0006-3592
No coin nor oath required. For personal study only.
✦ Synopsis
Process control of anaerobic reactors is difficult
Direct process control of these reactors is difficult due to the complexity of the methabolic pathways in the due to the complexity of the methabolic pathways in microbial consortium and to the difficulty of detecting the microbial consortium and to the difficulty of deand monitoring process instability in short time, before tecting and monitoring process instability in short time, the biomass is poisoned by incoming toxicants. Process before the biomass is poisoned by incoming toxicants.
control based on the Rantox biosensor is based on the following principle: the wastewater that can potentially Several investigations have been carried out on expert induce an overload or contains a toxicant is first tested systems or other computerized strategies designed to on a small ''upstream'' digester (the Rantox). This reactor control the digesters ''on-line'' (Mathiot et al., 1992; makes possible to detect the potential instability and, if Barnett & Andrews, 1992).
necessary, to divert the concentrated and/or contami-These approaches allow monitoring of the real condinated wastewater to a buffer tank and consequently to protect the active biomass of the full-scale reactor. It is tions of the reactor, but by their own nature, the consegenerally accepted that methanogens are the most sensiquent control actions are possible only after the instabiltive microorganisms in anaerobic digestion. Among ity has somehow affected the operation of the reactor.
these bacteria, the acetoclastic methanogens are of pri-In case of organic overload this fact is not particularly mary importance because some 70% of the converted important, but in case of addition of toxicants the relechemical oxygen demand (COD) mass flow passes through acetic acid. Therefore the first objective in the vance could be different, especially if the effect of the development of the Rantox biosensor has been to monitoxic compound does build up slowly and refers to more tor the metabolism of acetoclastic methanogens in the or less irreversible toxicity. presence of toxicants. This article presents the theoretical Process control based on the Rantox biosensor makes background required to evaluate the toxicity effects by use of a somewhat different principle, already applied determining the kinetic constants of the considered microorganisms from experimental data. The results of two in aerobic treatment process control [e.g., the Rodtox series of calibration tests, performed in order to obtain (Vanrollegehem et al., 1994)]: The wastewater that can a preliminary evaluation of the biosensor response to potentially induce an overload or contains a toxicant is overload and toxicity conditions, are reported. In a second first tested on a small ''upstream'' digester (the Rantox).
article, calibration tests will be described which refer to This reactor makes it possible to detect the potential two prototypes of the biosensor tested in different operating conditions. The crucial point related to the Rantox, instability and, if necessary, to divert the concentrated i.e., its comparison with a ''normal'' laboratory-scale diand/or contaminated waste to a buffer tank and consegester to simulate a full-scale plant, will be the subject quently to protect the active biomass of the full-scale of the third (and last) article, which is planned to describe reactor.