ONCOFIRE · Online control of fixed-bed reactors applied to aerobic wastewater treatment
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2005-01-01 → 2006-12-31
- EU contribution
- €80,000
- Participants
- 1
- Scheme
- IRG
Lines connect the coordinator with its partners.
Results in brief
Final Activity Report Summary - ONCOFIRE (Online control of fixed-bed reactors applied to aerobic wastewater treatment)
Biological wastewater treatment and other processes using microbes to degrade noxious effluents or to produce compounds of industrial interest are well developed in our industrial society. In comparison to other reactor designs, i.e. pieces of equipment where the biological reaction takes place, fixed-bed biological reactors are of major interest for treating wastewater. In this reactor design, the microbial biomass that is in charge of the process is fixed on an inorganic carrier. Fixed-bed reactors are difficult to characterise and control due to the complexity of the process and the sampling difficulty. The aim of the project was to develop new methods for the characterisation of fixed-bed biomass. The proposed method was based on respirometry, which could be defined as the measurement of the oxygen uptake rate under controlled conditions. In particular, our project focussed on the measurement of the oxygen uptake rate after the injection of a pulse of substrate into the reactor. This method was called 'in-situ pulse respirometry'. The main results obtained showed that the injection of substrate pulses was effectively achieved in suspended biomass reactors and allowed for the retrieval of seven stoichiometric and kinetic parameters which were all important for the process characterisation. In case applied to fixed-bed reactors, the developed method was subject to some limitations. Indeed, we observed that the method could not be applied in reactors where the microbial growth generated non homogeneous hydrodynamic conditions. These application constraints were identified and were under analysis by the time of the project completion.
Data: CORDIS, © European Union
Project objective
Fixed bed reactors are often used in aerobic wastewater treatment. They are advantageously used in order to increase the biomass concentration within the reactor and are preferred when the maximum specific growth rate is close to the dilution rate to be applied. The use of carriers allows increasing significantly the microbial residence time and reduces the washing-out risk at short hydraulic retention times. One of the best given example of aerobic processes based on slow growing microbes is the so-called nitrification". Nitrification is the most commonly used nitrogen removal process and consists of aerobic ammonia oxidation to nitrites (nitritation) and then to nitrates (nitratation). Nitrosomonas and Nitrobacter genus are the major autotrophic groups involved in ammonia and nitrites oxidation, respectively. Both genus are characterised by a maximum specific growth rate ranging from 0.014 to 0.064 h-1, which are approximately 10 times lower than commonly accepted values for heterotrophic microbes. These specific growth rates implies that in suspended biomass reactor (CSTR, for instance) the hydraulic retention time must be kept higher than 15 to 70 hours, to avoid biomass wash-out.By comparison, fixed-bed nitrification reactors can work at residence time lower than five hours. Fixed -bed reactors are therefore an important tool for wastewater treatment and nitrification is probably the best example of a biological process that can be advantageously integrated in fixed-bed reactors. Together with biomass measurements, respirometry allows the process characterisation. In fixed-bed reactors these measurements are significantly more complex than in suspended sludge reactors. The aim of this project is to develop new in-situ respirometric tools and associate t hem to stoichiometric measurements for on-line control of fixed-bed processes. Nitrification will be taken as first experimental model and the expected results will be applied to other fixed-bed process."
Original text from CORDIS.
Participants
- UNIVERSIDADE DO MINHO · BRAGACoordinatorPortugal
Links
Data: CORDIS, © European Union