Anaerobic digestion of thermal pre-treated emulsified slaughterhouse wastes (TESW): Effect of trace element limitation on process efficiency and sludge metabolic properties. (June 2018)

• Record Type: Journal Article
• Authors: Eftaxias, Alexandros; Diamantis, Vasileios; Aivasidis, Alexandros
• Is Part Of: Waste management. Volume 76(2018)
• Page Start: 357
• Page End: 363
• Publication Date: 2018-06
• Subjects: Slaughterhouse solid wastes -- Animal by-products -- Fat oil and grease -- Anaerobic digestion -- Trace elements -- Thermal emulsification; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2018.02.032
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: Thermal pre-treated slaughterhouse wastes were digested in a CSTR with biomass recirculation. Under optimum conditions COD removal was >96% and the biogas yield 0.53 L g −1 COD. A low trace element dosage resulted in COD and VFA accumulation, and sludge floatation. Anaerobic sludge metabolic activity was improved after inhibition from a low trace element dosage. Abstract: Slaughterhouse solid wastes, characterized by a high lipid content, are considered a valuable resource for energy production by means of anaerobic digestion technologies. Aim of this study was to examine the effect of trace element limitation on the mesophilic anaerobic digestion of thermally pre-treated emulsified slaughterhouse wastes (TESW). Under two distinct experimental periods (Period I – low and Period II – high trace element dosage respectively) a CSTR with sludge recirculation was operated at increasing organic loading rate (OLR) from 1.5 to 10 g L −1 d −1 . Under optimum conditions, COD removal was higher than 96%, biogas yield equal to 0.53 L g −1 COD feed and the biogas methane content 77%. Trace element limitation however, resulted in a dramatic decline in process efficiency, with VFA accumulation and events of extreme sludge flotation, despite that the soluble concentration of Ni, Co and Mo were between 12 and 28 μg L −1 . This is indicative of mass transfer limitations caused by lipids adsorption onto the anaerobic biomass.