title: An improved titration model reducing over estimation of total volatile fatty acids in anaerobic digestion of energy crop, animal slurry and food waste.
abstract: Titration methodologies have been used for the many years for low cost routine monitoring of full scale anaerobic digestion plants. These methodologies have been correlated to indicate the carbonate alkalinity and the volatile fatty acids (VFA) content within digesters. Two commonly used two end-point titration methods were compared using a dataset of 154 samples from energy crop and animal slurry digestates and were shown to be inaccurate in the estimation of tVFA. Using this dataset correlated with HPLC VFA analysis, two empirical bivariate linear regression equations were derived, where the validation dataset showed an absolute tVFA mean error improvement from ±3386 and ±3324 mg kg(-1) tVFA to ±410 and ±286 mg kg(-1) tVFA, respectively. The same equation was then applied to a food waste dataset where an absolute tVFA mean error was improved from ±3828 to ±576 mg kg(-1) tVFA. The newly derived titration equations can provide greater confidence in digester performance monitoring and are tools that can improve digester management.
authors.affiliation: Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, UK. Electronic address: ben.jobling-purser@southwales.ac.uk.
authors.forename: B J Jobling
authors.initials: BJ
authors.lastname: Purser
authors.affiliation: Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, UK.
authors.forename: S-M
authors.initials: SM
authors.lastname: Thai
authors.affiliation: ISF GmbH (Schaumann Research & Development), An der Mühlenau 4, D-25421 Pinneberg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Fritz
authors.affiliation: Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, UK.
authors.forename: S R
authors.initials: SR
authors.lastname: Esteves
authors.affiliation: Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Dinsdale
authors.affiliation: Sustainable Environment Research Centre, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Guwy
mesh_terms: D000693:Anaerobiosis; D002851:Chromatography, High Pressure Liquid; D005232:Fatty Acids, Volatile / Q000032:analysis*; D008372:Manure / Q000032:analysis*; D008962:Models, Theoretical; D012037:Refuse Disposal / Q000379:methods*; D062611:Solid Waste / Q000032:analysis*
chemical_list: D005232:Fatty Acids, Volatile; D008372:Manure; D062611:Solid Waste
keywords: Anaerobic digestion; Digester stability; Empirical model; Process monitoring; Titration volatile fatty acids