title: Semi-continuous anaerobic co-digestion of orange peel waste and residual glycerol derived from biodiesel manufacturing.
abstract: The manufacturing of orange juice generates high volumes of orange peel waste which should not be deposited in landfill according to current recommendations. Furthermore, glycerol is a compound co-generated in biodiesel manufacturing, but the volume generated is higher than the current demand for pure glycerol. The anaerobic co-digestion of orange peel waste with residual glycerol could reduce the inhibitory effect of some compounds and provide a correct nutrient balance. Under mesophilic temperature and semi-continuous conditions, a mixture of orange peel waste-residual glycerol of 1:1 (in COD) operated favorably for organic loads up to 2.10 g VS/L. At higher organic loads, the accumulation of volatile fatty acids (VFA) and a decrease in the pH caused process destabilization. The methane yield coefficient was quite constant, with a mean value of 330±51 mL(STP)/g VSadded, while the organic loading rate (OLR) reached a mean value of 1.91±0.37 kgVS/m3 d (17.59±2.78 kgmixture/m3 d) and the hydraulic retention time (HRT) varied in a range of 8.5-30.0 d.
authors.affiliation: Inorganic Chemistry and Chemical Engineering Department, University of Cordoba, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Martín
authors.forename: R
authors.initials: R
authors.lastname: Fernández
authors.forename: A
authors.initials: A
authors.lastname: Serrano
authors.forename: J A
authors.initials: JA
authors.lastname: Siles
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D056804:Biofuels; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D032084:Citrus sinensis / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000378:metabolism; D019649:Food Industry; D005990:Glycerol / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007700:Kinetics; D008697:Methane / Q000096:biosynthesis; D013696:Temperature; D018505:Waste Management / Q000295:instrumentation / Q000379:methods*
chemical_list: D056804:Biofuels; D005232:Fatty Acids, Volatile; D007220:Industrial Waste; D008697:Methane; D005990:Glycerol