Anaerobic model for high-solids or high-temperature digestion - additional pathway of acetate oxidation.
Current anaerobic digestion models cannot properly simulate processes that are operated under high solids concentrations or high temperatures. A modification to existing models has been implemented by adding important missing degradation pathways, to accommodate these systems without artificially recalibrating the model parameters. Specifically, we implemented the alternate acetate oxidizing mechanism that is more tolerant to ammonia than the standard aceticlastic pathway. Inhibition values were estimated and an empirical function has been used to apply ammonia inhibition. The model also relates metabolic activity to un-ionised species such as undissociated acetic acid as substrate (although not obligatory for all organisms) and unionised ammonia as inhibitor. The model relies on an equilibrium chemistry module (e.g. including the phosphate buffer), resulting in more accurate pH predictions, which is crucial for proper modeling of CO2 and NH3 stripping. Calibration results from three case-studies modeling thermal hydrolysis and subsequent digestion of sludge are presented.
ARAconsult, Unterbergerstr.1, A-6020 Innsbruck, Austria E-mail: wett@araconsult.at.
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Wett
Dynamita, 66 bis Avenue du Parc d'Espagne, Pessac, Bordeaux, France.
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Takács
Advanced Water Management Centre, The University of Queensland, St Lucia 4072, Australia.
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Batstone
Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA 24060, USA.
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Wilson
DC Water, DWT, 5000 Overlook Ave, SW Washington, DC 20032, USA.
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Murthy
D000085:Acetates / Q000737:chemistry* / Q000378:metabolism*; D000641:Ammonia / Q000737:chemistry; D000693:Anaerobiosis; D019149:Bioreactors; D006358:Hot Temperature; D008954:Models, Biological; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism*
D000085:Acetates; D014874:Water Pollutants, Chemical; D000641:Ammonia