Grasas y Aceites, Vol 49, No 1 (1998)

Effect of organic loading rate on anaerobic digestion process of wastewaters from the washing of olives prior to the oil production process in a fluidized bed reactor


https://doi.org/10.3989/gya.1998.v49.i1.707

Rafael Borja
Instituto de la Grasa (CSIC)., Spain

José Alba
Instituto de la Grasa (CSIC)., Spain

Antonio Martín
Departamento de Ingeniería Química. Facultad de Ciencias. Universidad de Córdoba., Spain

Angela Mancha
Instituto de la Grasa (CSIC)., Spain

Abstract


A study of the anaerobic digestion process of wastewaters from the washing of olives prior to the oil production process was carried out in a fluidized bed reactor with sepiolite immobilised biomass at 35°G. The bioreactor worked satisfactorily using Influent COD concentrations of 4.5,3.5,2.5 and 1.5 g COD/I for a hydraulic retention time (HRT) range of 4.5 to 1,25 days. COD removal efficiencies in the range 50-90% were achieved in the reactor, when evaluated at organic loading rates of between 0.46 and 2.25 g COD/I day using the highest influent substrate concentration (So = 4.5 g COD/I). COD and volatile fatty acid (VFA) concentration were Increased In parallel with the increase of organic loading rate in the reactor, VFA concentration showing a maximum value of 1.55 g acetic acid/I at the most unfavourable case studied (So = 4,5 g COD/I and HRT = 1.25 days). The increase in effluent VFA concentrations was always counteracted by the high alkalinity values (3440-4670 mg CaCO3/l) which brought about the high stability of the process and values of the alkalinity/VFA ratio lower than 0.3-0.5, except for the above-mentioned case, limit value over which the anaerobic process is destabilized. The yield coefficient of methane production was 0.281 methane STP/g COD removed.

Keywords


Anaerobic digestion; Continuous regime; Fluidized bed; Olive; Waste water from washing.

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