Transflexive embedded near infrared monitoring for key process intermediates in anaerobic digestion/biogas production. An Abstract from Journal of Near Infrared Spectroscopy

Jens Bo Holm-Nielsen,^a,* Helga Andree,^b Harald Lindorfer^c and Kim H. Esbensen^a
^aACABS Research Group, Esbjerg Institute of Technology, Aalborg University, Niels Bohrs Vej 8, 6700 Esbjerg, Denmark. E-mail: jhn@aaue.dk
^bInstitute of Agricultural Process Engineering, University of Kiel, Germany
^cInstitute for Environmental Biotechnology, Department for Agrobiotechnology (IFA), University of Natural Resources and Applied Life Sciences, Vienna, Austria

This work reports an off-line method development simulating at-line anaerobic co-digestion process monitoring using a new transflexive embedded near infrared sensor (TENIRS) system as a process analytical chemistry (PAC) facility. The operative focus is on optimising anaerobic digestion biogas production with energy crops as the main feedstock. Results show that several key monitoring intermediates in the anaerobic fermentation process can be quantified directly using near infrared spectroscopy with good results, especially ammonium and total volatile fatty acids. Good feasibility study prediction validations have been obtained for total solids (TS), volatile solids (VS), ammonium, acetic acid and total volatile fatty acids. The TENIRS system is a new option for real-time, at-line/on-line monitoring of biogas fermentation operations, offering a robust, low-budget PAC approach to a rapidly growing bulk volume industry.