107 results on '"Volcke E"'
Search Results
2. Modelling salinity effects on aerobic granular sludge treating fish-canning wastewater
- Author
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Carrera, P., primary, Strubbe, L., additional, Val del Río, A., additional, Mosquera-Corral, A., additional, and Volcke, E. I. P., additional
- Published
- 2023
- Full Text
- View/download PDF
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3. Model-based analysis of sulfur-based denitrification in a moving bed biofilm reactor
- Author
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Decru, S. O., Baeten, J. E., Cui, Y.-X., Wu, D., Chen, G.-H., and Volcke, E. I. P.
- Abstract
In this study, a biofilm model was developed for sulfur-based denitrification in a moving bed biofilm reactor (MBBR), including mass transport as well as the conversion kinetics of sulfur-oxidizing bacteria (SOB). The experimental reactor simulated received a synthetic wastewater containing nitrate, sulfide and thiosulfate. The substrate affinity of SOB for intermediary elemental sulfur (S0) was found the most sensitive parameter. After estimating this single parameter, the model could adequately describe the steady state performance of the experimental MBBR. The experimental and simulated mass balances indicated that a fraction of influent sulfur accumulated into intermediate S0. Furthermore, the simulations showed that SOB were active over the entire thickness of a 200 µm biofilm. The simulation results allowed to quantify the extent of diffusion and substrate limitation. Scenario analyses indicated that the specific nitrogen loading rate could be increased from 0.05 to 0.20 kg N.kg−1 VSS.day−1 (corresponding to 0.22–0.86 kg N.m−2.day−1 expressed per biofilm surface area) while maintaining nitrogen removal efficiencies above 70%. An increasing specific nitrogen loading rate in this range resulted in an almost linearly increasing specific nitrogen removal rate, independent from whether it was realized through a decreasing HRT, carrier filling ratio or biofilm thickness. more...
- Published
- 2021
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- View/download PDF
4. Model-based analysis of sulfur-based denitrification in a moving bed biofilm reactor.
- Author
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Decru, S. O., Baeten, J. E., Cui, Y.-X., Wu, D., Chen, G.-H., and Volcke, E. I. P.
- Subjects
MOVING bed reactors ,DENITRIFICATION - Abstract
In this study, a biofilm model was developed for sulfur-based denitrification in a moving bed biofilm reactor (MBBR), including mass transport as well as the conversion kinetics of sulfur-oxidizing bacteria (SOB). The experimental reactor simulated received a synthetic wastewater containing nitrate, sulfide and thiosulfate. The substrate affinity of SOB for intermediary elemental sulfur (S
0 ) was found the most sensitive parameter. After estimating this single parameter, the model could adequately describe the steady state performance of the experimental MBBR. The experimental and simulated mass balances indicated that a fraction of influent sulfur accumulated into intermediate S0 . Furthermore, the simulations showed that SOB were active over the entire thickness of a 200 µm biofilm. The simulation results allowed to quantify the extent of diffusion and substrate limitation. Scenario analyses indicated that the specific nitrogen loading rate could be increased from 0.05 to 0.20 kg N.kg−1 VSS.day−1 (corresponding to 0.22–0.86 kg N.m−2 .day−1 expressed per biofilm surface area) while maintaining nitrogen removal efficiencies above 70%. An increasing specific nitrogen loading rate in this range resulted in an almost linearly increasing specific nitrogen removal rate, independent from whether it was realized through a decreasing HRT, carrier filling ratio or biofilm thickness. [ABSTRACT FROM AUTHOR] more...- Published
- 2022
- Full Text
- View/download PDF
5. Model-based analysis of sulfur-based denitrification in a moving bed biofilm reactor
- Author
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Decru, S. O., primary, Baeten, J. E., additional, Cui, Y.-X., additional, Wu, D., additional, Chen, G.-H., additional, and Volcke, E. I. P., additional
- Published
- 2021
- Full Text
- View/download PDF
6. Onderzoeksrapport Pocket Power
- Author
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Vandendriessche, S., Verleden, I., Dobbelaere, A. De, Leenknegt, J., Vergote, T., Meers, E., Volcke, E., Buysse, J., Vandendriessche, S., Verleden, I., Dobbelaere, A. De, Leenknegt, J., Vergote, T., Meers, E., Volcke, E., and Buysse, J. more...
- Published
- 2020
7. Heat recovery during treatment of highly concentrated wastewater: economic evaluation and influencing factors
- Author
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Corbala-Robles, L., primary, Ronsse, F., primary, Pieters, J. G., primary, and Volcke, E. I. P., primary
- Published
- 2018
- Full Text
- View/download PDF
8. Trickling filters following anaerobic sewage treatment: state of the art and perspectives
- Author
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Bressani-Ribeiro, T., primary, Almeida, P. G. S., additional, Volcke, E. I. P., additional, and Chernicharo, C. A. L., additional
- Published
- 2018
- Full Text
- View/download PDF
9. Quo Vadis Benchmark Simulation Models? 8th IWA Symposium on Systems Analysis and Integrated Assessment
- Author
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Jeppsson, U., Alex, J., D, Batstone, Benedetti, L., Comas, J., Copp, J. B., Corominas, L., Xavier Flores Alsina, Krist Gernaey, Nopens, I., Rodriguez-Roda, I., Rosen, C., P Steyer, J., Vanrolleghem, P. A., Volcke, E. I. P., and Vrecko, D. more...
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Benchmarking ,Process monitoring ,Control ,BSM ,Wastewater treatment ,Evaluation ,Simulation ,Modelling - Abstract
As the work of the IWA Task Group on Benchmarking of Control Strategies for WWTPs is coming towards an end, it is essential to disseminate the knowledge gained. For this reason, all authors of the IWA Scientific and Technical Report on benchmarking have come together to provide their insights, highlighting areas where knowledge may still be deficient and where new opportunities are emerging, and to propose potential avenues for future development and application of the general benchmarking framework and its associated tools. The paper focuses on the topics of temporal and spatial extension, process modifications within the WWTP, the realism of models, control strategy extensions and the potential for new evaluation tools within the existing benchmark system. more...
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- 2011
10. Modelling microbial competition in nitrifying biofilm reactors
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Vannecke, T. P. W., primary and Volcke, E. I. P., additional
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- 2015
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11. Modelling ammonium-oxidizing population shifts in a biofilm reactor
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Vannecke, T. P. W., primary, Bernet, N., primary, Steyer, J.-P., primary, and Volcke, E. I. P., primary
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- 2013
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12. Benchmark simulation models, quo vadis?
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Jeppsson, U., primary, Alex, J., primary, Batstone, D. J., primary, Benedetti, L., primary, Comas, J., primary, Copp, J. B., primary, Corominas, L., primary, Flores-Alsina, X., primary, Gernaey, K. V., primary, Nopens, I., primary, Pons, M.-N., primary, Rodríguez-Roda, I., primary, Rosen, C., primary, Steyer, J.-P., primary, Vanrolleghem, P. A., primary, Volcke, E. I. P., primary, and Vrecko, D., primary more...
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- 2013
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13. Modelling nitrous and nitric oxide emissions by autotrophic ammonia-oxidizing bacteria
- Author
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Mampaey, K. E., primary, Beuckels, B., additional, Kampschreur, M. J., additional, Kleerebezem, R., additional, van Loosdrecht, M. C.M., additional, and Volcke, E. I.P., additional
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- 2013
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14. Methane and nitrous oxide emissions from municipal wastewater treatment – results from a long-term study
- Author
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Daelman, M. R. J., primary, van Voorthuizen, E. M., primary, van Dongen, L. G. J. M., primary, Volcke, E. I. P., primary, and van Loosdrecht, M. C. M., primary
- Published
- 2013
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15. N2O and NO emissions during autotrophic nitrogen removal in a granular sludge reactor – a simulation study
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Van Hulle, S. W.H., primary, Callens, J., additional, Mampaey, K. E., additional, van Loosdrecht, M. C.M., additional, and Volcke, E. I.P., additional
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- 2012
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16. Systematic model development for partial nitrification of landfill leachate in a SBR
- Author
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Ganigué, R., primary, Volcke, E. I. P., primary, Puig, S., primary, Balaguer, M. D., primary, Colprim, J., primary, and Sin, G., primary
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- 2010
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17. Improved nitrogen removal by application of new nitrogen-cycle bacteria (Review)
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Jetten, M.S.M., Schmid, M., Schmidt, I., Wubben, M., Dongen, U. van, Abma, W., Sliekers, O., Revsbech, N.P., Beaumont, H.J.E, Ottosen, L., Volcke, E., Laanbroek, H.J., Campos-Gomez, J.L., Cole, J., Loosdrecht, M. van, Mulder, J.W., Fuerst, J., Richardson, D., Pas, K. van de, Mendez-Pampin, R., Third, K., Cirpus, I., Spanning, R. van, Bollmann, A., Nielsen, L.P., Camp, H. op den, Schultz, C., Gundersen, J., Vanrolleghem, P., Strous, M., Wagner, M., Kuenen, J.G., Jetten, M.S.M., Schmid, M., Schmidt, I., Wubben, M., Dongen, U. van, Abma, W., Sliekers, O., Revsbech, N.P., Beaumont, H.J.E, Ottosen, L., Volcke, E., Laanbroek, H.J., Campos-Gomez, J.L., Cole, J., Loosdrecht, M. van, Mulder, J.W., Fuerst, J., Richardson, D., Pas, K. van de, Mendez-Pampin, R., Third, K., Cirpus, I., Spanning, R. van, Bollmann, A., Nielsen, L.P., Camp, H. op den, Schultz, C., Gundersen, J., Vanrolleghem, P., Strous, M., Wagner, M., and Kuenen, J.G. more...
- Published
- 2002
18. Calculating pH in pig manure taking into account ionic strength
- Author
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Nielsen, A. M., primary, Spanjers, H., additional, and Volcke, E. I. P., additional
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- 2008
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19. Combined anaerobic digestion and biological nitrogen removal for piggery wastewater treatment: a modelling approach
- Author
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Rousseau, P., primary, Steyer, J.-P., primary, Volcke, E. I. P, primary, Bernet, N., primary, and Béline, F., primary
- Published
- 2008
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20. An overview of the posters presented at Watermatex 2000. II. Sensor/monitoring, control and decision support systems
- Author
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Volcke, E. I., primary, Clement, L., additional, Van De Steene, M., additional, and Vanrolleghem, P. A., additional
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- 2001
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21. Modelling ammonium-oxidizing population shifts in a biofilm reactor.
- Author
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Vannecke, T. P. W., Bernet, N., Steyer, J.-P., and Volcke, E. I. P.
- Subjects
BIOFILMS ,NITRIFICATION ,AMMONIA-oxidizing bacteria ,NITROSOMONAS europaea ,DISSOLVED oxygen in water ,BIOMASS - Abstract
The dynamic reactor behaviour of a nitrifying inverse turbulent bed reactor, operated at varying loading rate, was described with a one-dimensional two-step nitrification biofilm model. In contrast with conventional biofilm models, this model includes the competition between two genetically different populations of ammonia-oxidizing bacteria (AOB), besides nitrite-oxidizing bacteria (NOB). Previously gathered experimental evidence showed that different loading rates in the reactor resulted in a change in the composition of the AOB community, besides a different nitrifying performance. The dissolved oxygen concentration in the bulk liquid was put forward as the key variable governing the experimentally observed shift from Nitrosomonas europaea (AOB1) to Nitrosomonas sp. (AOB2), which was confirmed by the developed one-dimensional biofilm model. Both steady state and dynamic analysis showed that the influence of microbial growth and endogenous respiration parameters as well as external mass transfer limitation have a clear effect on the competition dynamics. Overall, it was shown that the biomass distribution profiles of the coexisting AOB reflected the ecological niches created by substrate gradients. [ABSTRACT FROM AUTHOR] more...
- Published
- 2014
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22. N 2 O and NO emissions during autotrophic nitrogen removal in a granular sludge reactor – a simulation study.
- Author
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Van Hulle, S. W.H., Callens, J., Mampaey, K. E., van Loosdrecht, M. C.M., and Volcke, E. I.P.
- Subjects
NITROGEN oxides & the environment ,NITROGEN dioxide & the environment ,EMISSIONS (Air pollution) ,CHEMICAL reactors ,SLUDGE management ,SIMULATION methods & models ,MATHEMATICAL statistics - Abstract
This contribution deals with NO and N2O emissions during autotrophic nitrogen removal in a granular sludge reactor. Two possible model scenarios describing this emission by ammonium- oxidizing biomass have been compared in a simulation study of a granular sludge reactor for one-stage partial nitritation–Anammox. No significant difference between these two scenarios was noticed. The influence of the bulk oxygen concentration, granule size, reactor temperature and ammonium load on the NO and N2O emissions has been assessed. The simulation results indicate that emission maxima of NO and N2O coincide with the region for optimal Anammox conversion. Also, most of the NO and N2O are present in the off-gas, owing to the limited solubility of both gases. The size of granules needs to be large enough not to limit optimal Anammox activity, but not too large as this implies an elevated production of N2O. Temperature has a significant influence on N2O emission, as a higher temperature results in a better N-removal efficiency and a lowered N2O production. Statistical analysis of the results showed that there is a strong correlation between nitrite accumulation and N2O production. Further, three regions of operation can be distinguished: a region with high N2O, NO and nitrite concentration; a region with high N2 concentrations and, as such, high removal percentages; and a region with high oxygen and nitrate concentrations. There is some overlap between the first two regions, which is in line with the fact that maximum emission of NO and N2O coincides with the region for optimal Anammox conversion. [ABSTRACT FROM AUTHOR] more...
- Published
- 2012
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23. Effect of granule size on autotrophic nitrogen removal in a granular sludge reactor.
- Author
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Volcke, E. I. P., Picioreanu, C., De Baets, B., and van Loosdrecht, M. C. M.
- Subjects
BIOFILMS ,OXYGEN ,SEWAGE sludge ,BULK solids ,CHEMICAL reactors - Abstract
Autotrophic nitrogen removal through sequential partial nitritation and anammox reactions can be achieved in biofilm reactors by controlling the oxygen concentration in the bulk liquid in such a way that nitrite oxidizers are outcompeted by anammox bacteria. In the case of granular sludge reactors, the granule size may influence the optimal range of oxygen concentration, as has been confirmed in the present study by means of numerical simulations. The range of oxygen concentrations for which combined partial nitritation and anammox conversion is established becomes broader for larger particles and with increasing influent ammonium concentrations. At the same time the likelihood of nitrite accumulation in the reactor effluent also increases. [ABSTRACT FROM AUTHOR] more...
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- 2010
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24. Interaction between control and design of a SHARON reactor: economic considerations in a plant-wide (BSM2) context.
- Author
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Volcke, E. I. P., Van Loosdrecht, M. C. M., and Vanrolleghem, P. A.
- Subjects
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NITROGEN removal (Sewage purification) , *DENITRIFICATION , *SEWAGE sludge , *AMMONIA , *NITROGEN compounds , *SEWAGE sludge digestion - Abstract
The combined SHARON-Anammox process is a promising technique for nitrogen removal from wastewater streams with high ammonium concentrations. It is typically applied to sludge digestion reject water, in order to relieve the activated sludge tanks, to which this stream is typically recycled. This contribution assesses the impact of the applied control strategy in the SHARON-reactor, both on the effluent quality of the subsequent Anammox reactor as well as on the plant-wide level by means of an operating cost index. Moreover, it is investigated to which extent the usefulness of a certain control strategy depends on the reactor design (volume). A simulation study is carried out using the plant-wide Benchmark Simulation Model no. 2 (BSM2), extended with the SHARON and Anammox processes. The results reveal a discrepancy between optimizing the reject water treatment performance and minimizing plant-wide operating costs. [ABSTRACT FROM AUTHOR] more...
- Published
- 2007
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25. Operation of a SHARON nitritation reactor: practical implications from a theoretical study.
- Author
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Volcke, E. I. P., Loccufier, M., Noldus, E. J. L., and Vanrolleghem, P. A.
- Subjects
- *
WATER quality management , *NITRIFICATION , *BIOREACTORS , *WASTEWATER treatment , *SYSTEM analysis , *MATHEMATICAL models , *INDUSTRIAL wastes , *BIOLOGICAL nutrient removal , *NITROGEN removal (Sewage purification) - Abstract
This contribution deals with the behaviour of a SHARON reactor for nitrogen removal from wastewater streams with high ammonium concentrations. A system analysis is performed on a two-step nitrification model, describing the behaviour of such a reactor. Steady states are identified through direct calculation using a canonical state space model representation. Practical operation of a SHARON reactor aims at reaching ammonium conversion to nitrite only (nitritation), while suppressing further conversion to nitrate. It is shown how this desired behaviour can be obtained by setting the dilution rate dependent on the influent ammonium concentration. The impact of microbial growth characteristics on the suitable operating region is examined, as well as the effect of reactor temperature and pH. Advice is given for robust reactor design and operation. [ABSTRACT FROM AUTHOR] more...
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- 2007
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26. Plant-wide (BSM2) evaluation of reject water treatment with a SHARON-Anammox process.
- Author
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Volcke, E. I. P., Gernaey, K. V., Vrecko, D., Jeppsson, U., Van Loosdrecht, M. C. M., and Vanrolleghem, P. A.
- Subjects
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SEWAGE purification , *EFFLUENT quality , *NITROGEN , *WATER quality management , *SEWAGE sludge digestion , *SIMULATION methods & models , *OPERATING costs - Abstract
In wastewater treatment plants (WWTPs) equipped with sludge digestion and dewatering systems, the reject water originating from these facilities contributes significantly to the nitrogen load of the activated sludge tanks, to which it is typically recycled. In this paper, the impact of reject water streams on the performance of a WWTP is assessed in a simulation study, using the Benchmark Simulation Model no. 2 IBSM2), that includes the processes describing sludge treatment and in this way allows for plant-wide evaluation. Comparison of performance of a WWTP without reject water with a WWTP where reject water is recycled to the primary clarifier, i.e. the BSM2 plant, shows that the ammonium load of the influent to the primary clarifier is 28% higher in the case of reject water recycling. This results in violation of the effluent total nitrogen limit. In order to relieve the main wastewater treatment plant, reject water treatment with a combined SHARON-Anammox process seems a promising option. The simulation results indicate that significant improvements of the effluent quality of the main wastewater treatment plant can be realized. An economic evaluation of the different scenarios is performed using an Operating Cost Index (OCI). [ABSTRACT FROM AUTHOR] more...
- Published
- 2006
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27. Controlling the nitrite:ammonium ratio in a SHARON reactor in view of its coupling with an Anammox process.
- Author
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Volcke, E. I. P., van Loosdrecht, M. C. M., and Vanrouleghem, P. A.
- Subjects
- *
SEWAGE analysis , *INDUSTRIAL wastes , *AMMONIA , *NITRITES , *AMMONIUM , *NITROGEN compounds , *FEEDBACK control systems , *AUTOMATIC control systems , *AUTOMATION - Abstract
The combined SHARON—Anammox process for testing wastewater streams with high ammonia load is the focus of this paper. In particular, partial nitritation in the SHARON reactor should be performed to such an extent that a nitrite:ammonium ratio is generated which is optimal for full conversion in an Anammox process. In the simulation studies performed in this contribution, the nitrite:ammonium ratio produced in a SHARON process with fixed volume, as well as its effect on the subsequent Anammox process, is examined for realistic influent conditions and considering both direct and indirect pH effects on the SHARON process. Several possible operating modes for the SHARON reactor, differing in control strategies for O2, pH and the produced nitrite:ammonium ratio and based on regulating the air flow rate and/or acid/base addition, are systematically evaluated. The results are quantified through an operating coat index. Best results are obtained by means of cascade feedback control of the SHARON effluent nitrite:ammonium ratio through setting an O2 set-point that is tracked by adjusting the air flow rate, combined with single loop pH control through acid/base addition. [ABSTRACT FROM AUTHOR] more...
- Published
- 2006
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28. Coupling the SHARON process with Anammox: Model-based scenario analysis with focus on operating costs.
- Author
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Volcke, E. I. P., Van Hulle, S. W. H., Donckels, B. M. R., Van Loosdrecht, M. C. M., and Vanrolleghem, P. A.
- Subjects
- *
SEWAGE sludge digestion , *OXIDATION , *SIMULATION methods & models , *AMMONIUM , *AMMONIA & the environment , *NITROGEN compounds , *AIR flow , *HYDROGEN-ion concentration , *OPERATING ratios , *OPERATING costs - Abstract
The combined SHARON-Anammox process for treating wastewater streams with high ammonia concentration is discussed. Partial nitritation in the SHARON reactor should be performed to such an extent that an Anammox-optimal nitrite:ammonium ratio is generated. The SHARON process is typically applied to sludge digestion rejection water in order to relieve the ammonium load recycled to the main plant. A simulation study for realistic influent conditions on a SHARON reactor with a fixed volume and operated with constant air flow rate reveals that the actual nitrite:ammonium ratio might deviate significantly from the ideal ratio and might endanger operation of the subsequent Anammox reactor. It is further examined how the nitrite:ammonium ratio might be optimized. A cascade pH control strategy and a cascade O2 control strategy are tested. Simulation results are presented and the performance of the different strategies is assessed and quantified in an economic way by means of an operating cost index. Best results are obtained by means of cascade feedback control of the SHARON effluent nitrite:ammonium ratio through setting an O2-set-point that is tracked by adjusting the air flow rate. [ABSTRACT FROM AUTHOR] more...
- Published
- 2005
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- View/download PDF
29. Modelling nitrous oxide emissions from a Sharon reactor
- Author
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Mampaey, K. E., Beuckels, B., Kampschreur, M., Kleerebezem, R., Mark van Loosdrecht, and Volcke, E. I.
30. The effect of temperature and pH on the kinetics of a partial nitritation process
- Author
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Hulle, S. W., Volcke, E. I., López Teruel, J., Donckels, B., Loosdrecht, M. C., and Peter Vanrolleghem
31. Coupling the SHARON process with Anammox: Model-based scenario analysis with focus on operating costs
- Author
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Volcke, E. I. P., Hulle, S. W. H., Donckels, B. M. R., Mark van Loosdrecht, and Vanrolleghem, P. A.
32. Practical experiences with start-up and operation of a continuously aerated lab-scale SHARON reactor
- Author
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Hulle, S. W., Den Broeck, S., Maertens, J., Villez, K., Schelstraete, G., Volcke, E. I., and Peter Vanrolleghem
33. Sulfur transformations during two-stage anaerobic digestion and intermediate thermal hydrolysis.
- Author
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Forouzanmehr F, Solon K, Maisonnave V, Daniel O, Volcke EIP, Gillot S, and Buffiere P
- Subjects
- Anaerobiosis, Hydrolysis, Sulfur, Sewage, Wastewater
- Abstract
The formation of hydrogen sulfide (H
2 S) during anaerobic digestion (AD) imposes constraints on the valorisation of biogas. So far, inorganic sulfur compounds -mainly sulfate - have been considered as the main contributors to H2 S formation, while the contribution of organic sulfur compounds is mostly neglected. This study investigates the fate of organic and inorganic sulfur compounds during two-stage anaerobic digestion with intermediate thermal hydrolysis for treatment of primary and secondary sludge in a WWTP treating domestic wastewater. The results of a seven-week monitoring campaign showed an overall decrease of organic sulfur compounds in both stages of anaerobic digestion. Further fractionation of organic sulfur revealed a high conversion of the particulate organic fraction during the first digestion stage and of the soluble organic fraction during the second digestion stage. The decrease of soluble organic sulfur during the second digestion stage was attributed to the solubilisation and hydrolysis of sulfur-containing organic compounds during thermal hydrolysis. In both digestion stages, more organic sulfur was taken up than particulate inorganic sulfur (metal sulfide) was produced, indicating the formation of other reduced sulfur forms (e.g. H2 S). Further batch experiments confirmed the role of organic sulfur uptake in the formation of H2 S during anaerobic digestion as sulfate reduction only partly explained the total sulfide formed (H2 S in biogas and precipitated FeS). Overall, the conversion of organic sulfur was demonstrated to play a major role in H2 S formation (and thus the biogas quality), especially in case of thermal hydrolysis pretreatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.) more...- Published
- 2022
- Full Text
- View/download PDF
34. Plant-wide investigation of sulfur flows in a water resource recovery facility (WRRF).
- Author
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Forouzanmehr F, Le QH, Solon K, Maisonnave V, Daniel O, Buffiere P, Gillot S, and Volcke EIP
- Subjects
- Sewage, Sulfur, Wastewater, Waste Disposal, Fluid, Water Resources
- Abstract
Even though sulfur compounds and their transformations may strongly affect wastewater treatment processes, their importance in water resource recovery facilities (WRRF) operation remains quite unexplored, notably when it comes to full-scale and plant-wide characterization. This contribution presents a first-of-a-kind, plant-wide quantification of total sulfur mass flows for all water and sludge streams in a full-scale WRRF. Because of its important impact on (post-treatment) process operation, the gaseous emission of sulfur as hydrogen sulfide (H
2 S) was also included, thus enabling a comprehensive evaluation of sulfur flows. Data availability and quality were optimized by experimental design and data reconciliation, which were applied for the first time to total sulfur flows. Total sulfur flows were successfully balanced over individual process treatment units as well as the plant-wide system with only minor variation to their original values, confirming that total sulfur is a conservative quantity. The two-stage anaerobic digestion with intermediate thermal hydrolysis led to a decreased sulfur content of dewatered sludge (by 36%). Higher (gaseous) H2 S emissions were observed in the second-stage digester (42% of total emission) than in the first one, suggesting an impact of thermal treatment on the production of H2 S. While the majority of sulfur mass flow from the influent left the plant through the treated effluent (> 95%), the sulfur discharge through dewatered sludge and gaseous emissions are critical. The latter are indeed responsible for odour nuisance, lower biogas quality, SO2 emissions upon sludge combustion and corrosion effects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.) more...- Published
- 2021
- Full Text
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35. Mass and heat balances for biological nitrogen removal in an activated sludge process: to couple or not to couple?
- Author
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Corbala-Robles L and Volcke EIP
- Subjects
- Bioreactors, Denitrification, Hot Temperature, Waste Disposal, Fluid, Wastewater, Nitrogen, Sewage
- Abstract
Models adapt constantly, usually increasing the degree of detail describing physical phenomena. In water resource recovery facilities, models based on mass and/or heat balances have been used to describe and improve operation. While both mass and heat balances have proven their worth individually, the question arises to which extent their coupling, which entails increased model complexity, warrants the supposedly more precise simulation results. In order to answer this question, the need for and effects of coupling mass and heat balances in modelling studies were evaluated in this work for a biological nitrogen removal process treating highly concentrated wastewater. This evaluation consisted on assessing the effect of the coupling of mass and heat balances on the prediction of: (1) nitrogen removal efficiency; (2) temperature; (3) heat recovery. In general, mass balances are sufficient for evaluating nitrogen removal efficiency and effluent nitrogen concentrations. If one desires to evaluate the effect of temperature changes (e.g. daily, weekly, seasonally) on nitrogen removal efficiency, the use of temperature profiles as an input variable to a mass balance-based model is recommended over the coupling of mass and heat balances. In terms of temperature prediction, considering a constant biological heat generation term in the heat balance model provides sufficient information - i.e. without the coupling of mass and heat balances. Also, for evaluating the heat recovery potential of the system, constant biological heat generation values provide valuable information, at least under normal operating conditions, i.e. when the solids retention time is large enough to maintain nitrification. more...
- Published
- 2021
- Full Text
- View/download PDF
36. Inorganic carbon limitation during nitrogen conversions in sponge-bed trickling filters for mainstream treatment of anaerobic effluent.
- Author
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Bressani-Ribeiro T, Almeida PGS, Chernicharo CAL, and Volcke EIP
- Subjects
- Anaerobiosis, Bioreactors, Carbon, Nitrification, Sewage, Waste Disposal, Fluid, Denitrification, Nitrogen analysis
- Abstract
Anaerobic sewage treatment is a proven technology in warm climate regions, and sponge-bed trickling filters (SBTFs) are an important post-treatment technology to remove residual organic carbon and nitrogen. Even though SBTFs can achieve a reasonably good effluent quality, further process optimization is hampered by a lack of mechanistic understanding of the factors influencing nitrogen removal, notably when it comes to mainstream anaerobically treated sewage. In this study, the factors that control the performance of SBTFs following anaerobic (i.e., UASB) reactors for sewage treatment were investigated. A demo-scale SBTF fed with anaerobically pre-treated sewage was monitored for 300 days, showing a median nitrification efficiency of 79% and a median total nitrogen removal efficiency of 26%. Heterotrophic denitrification was limited by the low organic carbon content of the anaerobic effluent. It was demonstrated that nitrification was impaired by a lack of inorganic carbon rather than by alkalinity limitation. To properly describe inorganic carbon limitation in models, bicarbonate was added as a state variable and sigmoidal kinetics were applied. The resulting model was able to capture the overall long-term experimental behaviour. There was no nitrite accumulation, which indicated that nitrite oxidizing bacteria were little or less affected by the inorganic carbon limitation. Overall, this study indicated the vital role of influent characteristics and operating conditions concerning nitrogen conversions in SBTFs treating anaerobic effluent, thus facilitating further process optimization., (Copyright © 2021. Published by Elsevier Ltd.) more...
- Published
- 2021
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37. Relating N 2 O emissions during biological nitrogen removal with operating conditions using multivariate statistical techniques.
- Author
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Vasilaki V, Volcke EIP, Nandi AK, van Loosdrecht MCM, and Katsou E
- Subjects
- Ammonium Compounds analysis, Ammonium Compounds metabolism, Bioreactors, Multivariate Analysis, Nitrates analysis, Nitrates metabolism, Nitrification, Nitrites analysis, Nitrites metabolism, Nitrogen analysis, Nitrogen metabolism, Oxygen analysis, Oxygen metabolism, Temperature, Waste Disposal, Fluid instrumentation, Waste Disposal, Fluid statistics & numerical data, Wastewater chemistry, Nitrous Oxide analysis, Waste Disposal, Fluid methods
- Abstract
Multivariate statistical analysis was applied to investigate the dependencies and underlying patterns between N
2 O emissions and online operational variables (dissolved oxygen and nitrogen component concentrations, temperature and influent flow-rate) during biological nitrogen removal from wastewater. The system under study was a full-scale reactor, for which hourly sensor data were available. The 15-month long monitoring campaign was divided into 10 sub-periods based on the profile of N2 O emissions, using Binary Segmentation. The dependencies between operating variables and N2 O emissions fluctuated according to Spearman's rank correlation. The correlation between N2 O emissions and nitrite concentrations ranged between 0.51 and 0.78. Correlation >0.7 between N2 O emissions and nitrate concentrations was observed at sub-periods with average temperature lower than 12 °C. Hierarchical k-means clustering and principal component analysis linked N2 O emission peaks with precipitation events and ammonium concentrations higher than 2 mg/L, especially in sub-periods characterized by low N2 O fluxes. Additionally, the highest ranges of measured N2 O fluxes belonged to clusters corresponding with NO3 -N concentration less than 1 mg/L in the upstream plug-flow reactor (middle of oxic zone), indicating slow nitrification rates. The results showed that the range of N2 O emissions partially depends on the prior behavior of the system. The principal component analysis validated the findings from the clustering analysis and showed that ammonium, nitrate, nitrite and temperature explained a considerable percentage of the variance in the system for the majority of the sub-periods. The applied statistical methods, linked the different ranges of emissions with the system variables, provided insights on the effect of operating conditions on N2 O emissions in each sub-period and can be integrated into N2 O emissions data processing at wastewater treatment plants., (Copyright © 2018. Published by Elsevier Ltd.) more...- Published
- 2018
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- View/download PDF
38. Plant-wide modelling of phosphorus transformations in wastewater treatment systems: Impacts of control and operational strategies.
- Author
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Solon K, Flores-Alsina X, Kazadi Mbamba C, Ikumi D, Volcke EIP, Vaneeckhaute C, Ekama G, Vanrolleghem PA, Batstone DJ, Gernaey KV, and Jeppsson U
- Subjects
- Phosphates chemistry, Sewage chemistry, Waste Disposal, Fluid, Phosphorus chemistry, Wastewater
- Abstract
The objective of this paper is to report the effects that control/operational strategies may have on plant-wide phosphorus (P) transformations in wastewater treatment plants (WWTP). The development of a new set of biological (activated sludge, anaerobic digestion), physico-chemical (aqueous phase, precipitation, mass transfer) process models and model interfaces (between water and sludge line) were required to describe the required tri-phasic (gas, liquid, solid) compound transformations and the close interlinks between the P and the sulfur (S) and iron (Fe) cycles. A modified version of the Benchmark Simulation Model No. 2 (BSM2) (open loop) is used as test platform upon which three different operational alternatives (A
1 , A2 , A3 ) are evaluated. Rigorous sensor and actuator models are also included in order to reproduce realistic control actions. Model-based analysis shows that the combination of an ammonium ( [Formula: see text] ) and total suspended solids (XTSS ) control strategy (A1 ) better adapts the system to influent dynamics, improves phosphate [Formula: see text] accumulation by phosphorus accumulating organisms (XPAO ) (41%), increases nitrification/denitrification efficiency (18%) and reduces aeration energy (Eaeration ) (21%). The addition of iron ( [Formula: see text] ) for chemical P removal (A2 ) promotes the formation of ferric oxides (XHFO-H , XHFO-L ), phosphate adsorption (XHFO-H,P , XHFO-L,P ), co-precipitation (XHFO-H,P,old , XHFO-L,P,old ) and consequently reduces the P levels in the effluent (from 2.8 to 0.9 g P.m-3 ). This also has an impact on the sludge line, with hydrogen sulfide production ( [Formula: see text] ) reduced (36%) due to iron sulfide (XFeS ) precipitation. As a consequence, there is also a slightly higher energy production (Eproduction ) from biogas. Lastly, the inclusion of a stripping and crystallization unit (A3 ) for P recovery reduces the quantity of P in the anaerobic digester supernatant returning to the water line and allows potential struvite ( [Formula: see text] ) recovery ranging from 69 to 227 kg.day-1 depending on: (1) airflow (Qstripping ); and, (2) magnesium ( [Formula: see text] ) addition. All the proposed alternatives are evaluated from an environmental and economical point of view using appropriate performance indices. Finally, some deficiencies and opportunities of the proposed approach when performing (plant-wide) wastewater treatment modelling/engineering projects are discussed., (Copyright © 2017 Elsevier Ltd. All rights reserved.) more...- Published
- 2017
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39. Continuous measurements of ammonia, nitrous oxide and methane from air scrubbers at pig housing facilities.
- Author
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Van der Heyden C, Brusselman E, Volcke EIP, and Demeyer P
- Subjects
- Agriculture, Animals, Environmental Pollution analysis, Nitrification, Swine, Air Pollutants analysis, Ammonia analysis, Environmental Monitoring, Housing, Animal, Methane analysis, Nitrous Oxide analysis
- Abstract
Ammonia, largely emitted by agriculture, involves a great risk for eutrophication and acidification leading to biodiversity loss. Air scrubbers are widely applied to reduce ammonia emission from pig and poultry housing facilities, but it is not always clear whether their performance meets the requirements. Besides, there is a growing international concern for the livestock related greenhouse gases methane and nitrous oxide but hardly any data concerning their fate in air scrubbers are available. This contribution presents the results from measurement campaigns conducted at a chemical, a biological and a two-stage biological air scrubber installed at pig housing facilities in Flanders. Ammonia, nitrous oxide and methane at the inlet and outlet of the air scrubbers were monitored on-line during one week using a photoacoustic gas monitor, which allowed to investigate diurnal fluctuations in the removal performance of air scrubbers. Additionally, the homogeneity of the air scrubbers, normally checked by gas detection tubes, was investigated in more detail using the continuous data. The biological air scrubber with extra nitrification tank performed well in terms of ammonia removal (86 ± 6%), while the two-stage air scrubber suffered from nitrifying bacteria inhibition. In the chemical air scrubber the pH was not kept constant, lowering the ammonia removal efficiency. A lower ammonia removal efficiency was found during the day, when the ventilation rate was the highest. Nitrous oxide was produced inside the biological and two-stage scrubber, resulting in an increased outlet concentration of more than 200%. Methane could not be removed in the different air scrubbers because of its low water solubility., (Copyright © 2016 Elsevier Ltd. All rights reserved.) more...
- Published
- 2016
- Full Text
- View/download PDF
40. Effect of foam on temperature prediction and heat recovery potential from biological wastewater treatment.
- Author
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Corbala-Robles L, Volcke EI, Samijn A, Ronsse F, and Pieters JG
- Subjects
- Hot Temperature, Models, Theoretical, Temperature, Wastewater
- Abstract
Heat is an important resource in wastewater treatment plants (WWTPs) which can be recovered. A prerequisite to determine the theoretical heat recovery potential is an accurate heat balance model for temperature prediction. The insulating effect of foam present on the basin surface and its influence on temperature prediction were assessed in this study. Experiments were carried out to characterize the foam layer and its insulating properties. A refined dynamic temperature prediction model, taking into account the effect of foam, was set up. Simulation studies for a WWTP treating highly concentrated (manure) wastewater revealed that the foam layer had a significant effect on temperature prediction (3.8 ± 0.7 K over the year) and thus on the theoretical heat recovery potential (30% reduction when foam is not considered). Seasonal effects on the individual heat losses and heat gains were assessed. Additionally, the effects of the critical basin temperature above which heat is recovered, foam thickness, surface evaporation rate reduction and the non-absorbed solar radiation on the theoretical heat recovery potential were evaluated., (Copyright © 2016 Elsevier Ltd. All rights reserved.) more...
- Published
- 2016
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41. Inoculum selection influences the biochemical methane potential of agro-industrial substrates.
- Author
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De Vrieze J, Raport L, Willems B, Verbrugge S, Volcke E, Meers E, Angenent LT, and Boon N
- Subjects
- Anaerobiosis, Biotransformation, Manure, Molasses, Methane metabolism, Microbial Consortia, Sewage microbiology, Waste Products
- Abstract
Obtaining a reliable estimation of the methane potential of organic waste streams in anaerobic digestion, for which a biochemical methane potential (BMP) test is often used, is of high importance. Standardization of this BMP test is required to ensure inter-laboratory repeatability and accuracy of the BMP results. Therefore, guidelines were set out; yet, these do not provide sufficient information concerning origin of and the microbial community in the test inoculum. Here, the specific contribution of the methanogenic community on the BMP test results was evaluated. The biomethane potential of four different substrates (molasses, bio-refinery waste, liquid manure and high-rate activated sludge) was determined by means of four different inocula from full-scale anaerobic digestion plants. A significant effect of the selected inoculum on the BMP result was observed for two out of four substrates. This inoculum effect could be attributed to the abundance of methanogens and a potential inhibiting effect in the inoculum itself, demonstrating the importance of inoculum selection for BMP testing. We recommend the application of granular sludge as an inoculum, because of its higher methanogenic abundance and activity, and protection from bulk solutions, compared with other inocula., (© 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.) more...
- Published
- 2015
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42. Modelling simultaneous anaerobic methane and ammonium removal in a granular sludge reactor.
- Author
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Winkler MK, Ettwig KF, Vannecke TP, Stultiens K, Bogdan A, Kartal B, and Volcke EI
- Subjects
- Anaerobiosis, Biomass, Bioreactors, Models, Theoretical, Oxidation-Reduction, Ammonium Compounds metabolism, Bacteria, Anaerobic metabolism, Methane metabolism, Nitrites metabolism, Sewage chemistry, Waste Disposal, Fluid
- Abstract
Anaerobic nitrogen removal technologies offer advantages in terms of energy and cost savings over conventional nitrification-denitrification systems. A mathematical model was constructed to evaluate the influence of process operation on the coexistence of nitrite dependent anaerobic methane oxidizing bacteria (n-damo) and anaerobic ammonium oxidizing bacteria (anammox) in a single granule. The nitrite and methane affinity constants of n-damo bacteria were measured experimentally. The biomass yield of n-damo bacteria was derived from experimental data and a thermodynamic state analysis. Through simulations, it was found that the possible survival of n-damo besides anammox bacteria was sensitive to the nitrite/ammonium influent ratio. If ammonium was supplied in excess, n-damo bacteria were outcompeted. At low biomass concentration, n-damo bacteria lost the competition against anammox bacteria. When the biomass loading closely matched the biomass concentration needed for full nutrient removal, strong substrate competition occurred resulting in oscillating removal rates. The simulation results further reveal that smaller granules enabled higher simultaneous ammonium and methane removal efficiencies. The implementation of simultaneous anaerobic methane and ammonium removal will decrease greenhouse gas emissions, but an economic analysis showed that adding anaerobic methane removal to a partial nitritation/anammox process may increase the aeration costs with over 20%. Finally, some considerations were given regarding the practical implementation of the process., (Copyright © 2015 Elsevier Ltd. All rights reserved.) more...
- Published
- 2015
- Full Text
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43. Specific growth rate observer for the growing phase of a Polyhydroxybutyrate production process.
- Author
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Jamilis M, Garelli F, Mozumder MS, Volcke E, and De Battista H
- Subjects
- Biomass, Cupriavidus necator growth & development, Hydroxybutyrates metabolism, Models, Biological, Polyesters metabolism
- Abstract
This paper focuses on the specific growth rate estimation problem in a Polyhydroxybutyrate bioplastic production process by industrial fermentation. The kinetics of the process are unknown and there are uncertainties in the model parameters and inputs. During the first hours of the growth phase of the process, biomass concentration can be measured online by an optical density sensor, but as cell density increases this method becomes ineffective and biomass measurement is lost. An asymptotic observer is developed to estimate the growth rate for the case without biomass measurement based on corrections made by a pH control loop. Furthermore, an exponential observer based on the biomass measurement is developed to estimate the growth rate during the first hours, which gives the initial condition to the asymptotic observer. Error bounds and robustness to uncertainties in the models and in the inputs are found. The estimation is independent of the kinetic models of the microorganism. The characteristic features of the observer are illustrated by numerical simulations and validated by experimental results. more...
- Published
- 2015
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44. Evaluation of the 5 and 8 pH point titration methods for monitoring anaerobic digesters treating solid waste.
- Author
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Vannecke TP, Lampens DR, Ekama GA, and Volcke EI
- Subjects
- Anaerobiosis, Chromatography, High Pressure Liquid, Hydrogen-Ion Concentration, Photometry, Fatty Acids, Volatile analysis, Garbage, Waste Management
- Abstract
Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness. more...
- Published
- 2015
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- View/download PDF
45. Effect of aeration regime on N₂O emission from partial nitritation-anammox in a full-scale granular sludge reactor.
- Author
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Castro-Barros CM, Daelman MR, Mampaey KE, van Loosdrecht MC, and Volcke EI
- Subjects
- Air Movements, Anaerobiosis, Nitrites metabolism, Oxidation-Reduction, Reproducibility of Results, Sewage microbiology, Waste Disposal, Fluid methods, Air, Ammonium Compounds metabolism, Bioreactors, Nitrification, Nitrous Oxide metabolism, Sewage chemistry
- Abstract
N₂O emission from wastewater treatment plants is high of concern due to the strong environmental impact of this greenhouse gas. Good understanding of the factors affecting the emission and formation of this gas is crucial to minimize its impact. This study addressed the investigation of the N₂O emission dynamics in a full-scale one-stage granular sludge reactor performing partial nitritation-anammox (PNA) operated at a N-loading of 1.75 kg NH₄⁺-N m⁻³ d⁻¹. A monitoring campaign was conducted, gathering on-line data of the N₂O concentration in the off-gas of the reactor as well as of the ammonium and nitrite concentrations in the liquid phase. The N₂O formation rate and the liquid N₂O concentration profile were calculated from the gas phase measurements. The mean (gaseous) N₂O-N emission obtained was 2.0% of the total incoming nitrogen during normal reactor operation. During normal operation of the reactor under variable aeration rate, intense aeration resulted in higher N₂O emission and formation than during low aeration periods (mean N₂O formation rate of 0.050 kg N m⁻³ d⁻¹ for high aeration and 0.029 kg N m⁻³ d⁻¹ for low aeration). Accumulation of N₂O in the liquid phase was detected during low aeration periods and was accompanied by a relatively lower ammonium conversion rate, while N₂O stripping was observed once the aeration was increased. During a dedicated experiment, gas recirculation without fresh air addition into the reactor led to the consumption of N₂O, while accumulation of N₂O was not detected. The transition from a prolonged period without fresh air addition and with little recirculation to enhanced aeration with fresh air addition resulted in the highest N₂O formation (0.064 kg N m⁻³ d⁻¹). The results indicate that adequate aeration control may be used to minimize N₂O emissions from PNA reactors. more...
- Published
- 2015
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46. Modelling microbial community dynamics in a nitrifying biofilm--effect of the nitrogen loading rate.
- Author
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Vannecke TP and Volcke EI
- Subjects
- Ammonium Compounds chemistry, Bacteria chemistry, Bioreactors microbiology, Kinetics, Models, Biological, Nitrites chemistry, Oxidation-Reduction, Ammonium Compounds metabolism, Bacteria metabolism, Biofilms, Nitrites metabolism
- Published
- 2014
47. Effect of nitrite pulses on N20 production during nitrification.
- Author
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Castro-Barros CM, Rodríguez-Caballero A, Volcke EI, and Pijuan M
- Subjects
- Biodegradation, Environmental, Bioreactors microbiology, Nitrification, Bacteria metabolism, Nitric Oxide metabolism, Nitrites metabolism, Sewage microbiology
- Published
- 2014
48. Biomethane potential of agro-industrial substrates depends on the inoculum type.
- Author
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Raport L, De Vrieze J, Willems B, Volcke EI, Meers E, and Boon N
- Subjects
- Agriculture, Animals, Archaea genetics, Bacteria genetics, Biomass, Crops, Agricultural, Industrial Waste, Linear Models, Polymerase Chain Reaction, RNA, Ribosomal, 16S genetics, RNA, Ribosomal, 16S metabolism, Sus scrofa, Archaea metabolism, Bacteria metabolism, Bioreactors microbiology, Methane metabolism, Sewage
- Published
- 2013
49. Online monitoring of N2O emissions from a partial nitritation (SHARON) reactor.
- Author
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Mampaey KE, Van Loosdrecht MC, and Volcke EI
- Subjects
- Bioreactors, Nitrification, Air Pollutants analysis, Environmental Monitoring methods, Nitrous Oxide analysis, Online Systems instrumentation, Spectroscopy, Fourier Transform Infrared methods, Waste Disposal, Fluid, Water Pollutants, Chemical analysis
- Published
- 2013
50. The granule size distribution in an anammox-based granular sludge reactor affects the conversion--implications for modeling.
- Author
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Volcke EI, Picioreanu C, De Baets B, and van Loosdrecht MC
- Subjects
- Ammonia isolation & purification, Autotrophic Processes, Equipment Design, Models, Biological, Nitrites isolation & purification, Nitrogen isolation & purification, Oxidation-Reduction, Particle Size, Software, Waste Disposal, Fluid methods, Ammonia metabolism, Bacteria metabolism, Bioreactors microbiology, Nitrites metabolism, Nitrogen metabolism, Sewage microbiology
- Abstract
Mathematical models are useful tools to optimize the performance of granular sludge reactors. In these models, typically a uniform granule size is assumed for the whole reactor, even though in reality the granules follow a size distribution and the granule size as such affects the process performance. This study assesses the effect of the granule size distribution on the performance of a granular sludge reactor in which autotrophic nitrogen removal is realized through one-stage partial nitritation-anammox. A comparison is made between different approaches to deal with particle size distributions in one-dimensional biofilm models, from the use of a single characteristic diameter to applying a multiple compartment model. The results show a clear impact on the conversion efficiency of the way in which particle size distribution is modeled, resulting from the effect of the granule size on the competition between nitrite oxidizing and anammox bacteria and from the interaction between granules of different sizes in terms of the exchange of solutes. Whereas the use of a uniform granule size is sufficient in case only the overall reactor behavior needs to be assessed, taking into account the detailed granule size distribution is required to study the solute exchange between particles of different sizes. For the latter purpose, the application of the widespread software package Aquasim is limited and the development of dedicated software applications is required., (Copyright © 2012 Wiley Periodicals, Inc.) more...
- Published
- 2012
- Full Text
- View/download PDF
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