Determination of Methane and Carbon Dioxide Formation Rate Constants for Semi-Continuously Fed Anaerobic DigestersReport as inadecuate




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1

Tekniska verken i Linköping AB public, Department of Biogas Research and Development, Box 1500, SE-581 15 Linköping, Sweden

2

Department of Microbiology, BioCenter, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden



These authors contributed equally to this work.



Present address: Swedish National Laboratory of Forensic Science, SE-581 94 Linköping, Sweden





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Author to whom correspondence should be addressed.



Academic Editor: Thomas E. Amidon

Abstract To optimize commercial-scale biogas production, it is important to evaluate the performance of each microbial step in the anaerobic process. Hydrolysis and methanogenesis are usually the rate-limiting steps during digestion of organic waste and by-products. By measuring biogas production and methane concentrations on-line in a semi-continuously fed reactor, gas kinetics can be evaluated. In this study, the rate constants of the fermentative hydrolysis step kc and the methanogenesis step km were determined and evaluated in a continuously stirred tank laboratory-scale reactor treating food and slaughterhouse waste and glycerin. A process additive containing Fe2+, Co2+ and Ni2+ was supplied until day 89, after which Ni2+ was omitted. The omission resulted in a rapid decline in the methanogenesis rate constant km to 70% of the level observed when Ni2+ was present, while kc remained unaffected. This suggests that Ni2+ mainly affects the methanogenic rather than the hydrolytic microorganisms in the system. However, no effect was initially observed when using conventional process monitoring parameters such as biogas yield and volatile fatty acid concentration. Hence, formation rate constants can reveal additional information on process performance and km can be used as a complement to conventional process monitoring tools for semi-continuously fed anaerobic digesters. View Full-Text

Keywords: anaerobic digestion; kinetics; rate constants; trace elements; nickel anaerobic digestion; kinetics; rate constants; trace elements; nickel





Author: Jan Moestedt 1,2,†, Jonas Malmborg 1,†,‡ and Erik Nordell 1,†,*

Source: http://mdpi.com/



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