Optimization of the anaerobic co-digestion of pasteurized slaughterhouse waste, pig slurry and glycerine. (March 2017)

• Record Type: Journal Article
• Authors: Rodríguez-Abalde, Ángela; Flotats, Xavier; Fernández, Belén
• Is Part Of: Waste management. Volume 61(2017)
• Page Start: 521
• Page End: 528
• Publication Date: 2017-03
• Subjects: Co-digestion -- Slaughterhouse waste -- Pig slurry -- Glycerin -- C/N ratio; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2016.12.022
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: A stepwise C/N ratio increase was proposed as optimization strategy. Animal by-products binary blends led to synergic effect on methane production yield. A ternary co-digestion mixture with glycerin as a carbon source was proposed. Glycerin was a profitable co-substrate if enough buffer capacity was kept. Abstract: The feasibility of co-digestion of blends of two different animal by-products (pig manure and pasteurized slaughterhouse waste) and recovered glycerine was studied in mesophilic conditions. Experiments were performed in a lab-scale CSTR along 490 days, with a hydraulic retention time of 21–33 days and with a step-wise increased organic loading rate, by adding and/or changing the wastes ratio, from 0.8 to 3.2 kgCOD m −3 d −1 . The best methane production rate (0.64 Nm 3 CH4 m −3 d −1 ) represented an increment of 2.9-fold the initial one (0.22 Nm 3 CH4 m −3 d −1 with pig manure solely). It was attained with a ternary mixture composed, in terms of inlet volatile solids, by 35% pig slurry, 47% pasteurized slaughterhouse waste and 18% glycerine. This blend was obtained through a stepwise C/N adjustment: this strategy led to a more balanced biodegradation due to unstressed bacterial populations through the performance, showed by the VFA-related indicators. Besides this, an improved methane yield (+153%) and an organic matter removal efficiency (+83%), regarding the digestion of solely pig slurry, were attained when the C/N ratio was adjusted to 10.3.