title: Mesophilic co-digestion of dairy manure and lipid rich solid slaughterhouse wastes: process efficiency, limitations and floating granules formation.
abstract: Lipid and protein rich solid slaughterhouse wastes are attractive co-substrates to increase volumetric biogas production in co-digestion with dairy manure. Addition of decanter sludge (DS), containing 42.2% of lipids and 35.8% of proteins (total solids basis), up to 5% of feed mixture resulted in a stable process without any indication of long chain fatty acids (LCFA) or free ammonia (NH3) inhibition and in 3.5-fold increase of volumetric biogas production. Contrary, only lipids addition as technical fat (TF) at over 2% of feed mixture resulted in formation of floating granules (FG) and process efficiency decrease. Formed FG had low biodegradability and its organic part was composed of lipids and calcium salts of LCFAs. Anaerobic digestion process intentionally directed to FG formation, could be a viable option for mitigation and control of lipids overload and derived LCFA inhibition.
authors.affiliation: Department of Chemistry, Tallinn University of Technology, 12618 Tallinn, Harjumaa, Estonia. Electronic address: peeppitk@gmail.com.
authors.forename: Peep
authors.initials: P
authors.lastname: Pitk
authors.affiliation: IRTA, GIRO Joint Research Unit IRTA-UPC, Torre Marimon, E-08140 Caldes de Montbui, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Palatsi
authors.affiliation: Department of Biological and Environmental Sciences, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland.
authors.forename: Prasad
authors.initials: P
authors.lastname: Kaparaju
authors.affiliation: IRTA, GIRO Joint Research Unit IRTA-UPC, Torre Marimon, E-08140 Caldes de Montbui, Barcelona, Spain.
authors.forename: Belén
authors.initials: B
authors.lastname: Fernández
authors.affiliation: Department of Chemistry, Tallinn University of Technology, 12618 Tallinn, Harjumaa, Estonia.
authors.forename: Raivo
authors.initials: R
authors.lastname: Vilu
mesh_terms: D000003:Abattoirs; D000383:Agriculture / Q000379:methods; D000818:Animals; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D056804:Biofuels; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002849:Chromatography, Gas; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D050356:Lipid Metabolism / Q000502:physiology*; D008372:Manure / Q000032:analysis*; D008697:Methane / Q000096:biosynthesis*; D013052:Spectrometry, X-Ray Emission; D014866:Waste Products / Q000032:analysis*
chemical_list: D056804:Biofuels; D005227:Fatty Acids; D008372:Manure; D014866:Waste Products; D008697:Methane; D002118:Calcium
keywords: Anaerobic digestion; Dairy manure; Long chain fatty acid (LCFA) inhibition; Solid slaughterhouse waste