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Updated: Jun 21, 2026

Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
Published on: July 13, 2012
Anaerobic digestion of glycerol derived from biodiesel manufacturing
José Angel Siles López1, María de Los Angeles Martín Santos, Arturo Francisco Chica Pérez
1Departamento de Química Inorgánica e Ingeniería Química, Facultad de Ciencias, Universidad de Córdoba, Campus Universitario de Rabanales, Edificio C-3, Ctra. Madrid-Cádiz, km 396, 14071 Córdoba, Spain. a92siloj@uco.es
Abstract:
The anaerobic digestion of glycerol derived from biodiesel manufacturing, in which COD was found to be 1010 g/kg, was studied in batch laboratory-scale reactors at mesophilic temperature using granular and non-granular sludge. Due to the high KOH concentration of this by-product, H(3)PO(4) was added to recover this alkaline catalyst as agricultural fertilizer (potassium phosphates). Although it would not be economically viable, a volume of glycerol was distilled and utilised as reference substrate. The anaerobic revalorisation of glycerol using granular sludge achieved a biodegradability of around 100%, while the methane yield coefficient was 0.306 m(3) CH(4)/kg acidified glycerol. Anaerobic digestion could be a good option for revalorising this available, impure and low priced by-product derived from the surplus of biodiesel companies. The organic loading rate studied was 0.21-0.38 g COD/g VSS d, although an inhibition phenomenon was observed at the highest load.
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