Ángela Rodríguez-Abalde1, Xavier Flotats2, Belén Fernández3. 1. IRTA, GIRO Joint Research Unit IRTA-UPC, Torre Marimon, E-08140, Caldes de Montbui, Barcelona, Spain; EnergyLab, Edificio CITEXVI - Local 1, Fonte das Abelleiras, s/n, Campus Universitario de Vigo, E-36310 Vigo, Spain. 2. GIRO Joint Research Unit IRTA-UPC, Department of Agrifood Engineering and Biotechnology, Universitat Politècnica de Catalunya - BarcelonaTECH, Parc Mediterrani de la Tecnologia, Building D-4, E-08860, Castelldefels, Barcelona, Spain. 3. IRTA, GIRO Joint Research Unit IRTA-UPC, Torre Marimon, E-08140, Caldes de Montbui, Barcelona, Spain. Electronic address: belen.fernandez@irta.cat.
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 490days, with a hydraulic retention time of 21-33days and with a step-wise increased organic loading rate, by adding and/or changing the wastes ratio, from 0.8 to 3.2kgCODm-3d-1. The best methane production rate (0.64Nm3CH4m-3d-1) represented an increment of 2.9-fold the initial one (0.22Nm3CH4m-3d-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.
The feasibility of co-digestion of blends of two different animal by-products (pig manure and pasteurized slaughterhouse waste) and recovered n class="Chemical">glycerine was studied in mesophilic conditions. Experiments were performed in a lab-scale CSTR along 490days, with a hydraulic retention time of 21-33days and with a step-wise increased organic loading rate, by adding and/or changing the wastes ratio, from 0.8 to 3.2kgCODm-3d-1. The best methane production rate (0.64Nm3CH4m-3d-1) represented an increment of 2.9-fold the initial one (0.22Nm3CH4m-3d-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.