Kinetic study of the anaerobic digestion of olive mill wastewater, from the oil extraction using olivex, previously biotreated with Geotrichum Candidum

Abstract

A kinetic study of the anaerobic digestion of olive mill wastewater (OMW) which was obtained with the technological helper "Olivex", was carried out. An identical wastewater, obtained without this enzyme was also used. Both OMW were pre-treated aerobically with Geotrichum Candidum to eliminate the greater part of the phenolic compounds responsible for inhibition. The anaerobic process was carried out in bioreactors with microorganisms immobilized on two micronized clay supports, Sepiolite and Bentonite. Assuming that the overall anaerobic digestion process conforms to a first-order kinetic, specific rate constants, Ko, were obtained by using the Roediger's equation in each case. In contrast to what takes place with both OMW without pretreatment, kinetic constant was observed virtually constant when the substrate concentration was increased, in the range of COD (chemical oxygen demand) studied. The mean value of this kinetic parameter was a 40% larger for the OMW obtained with Olivex compared to the reference OMW, in the two digesters used. Sepiolite favoured the kinetic and increased the yield coefficient compared to Bentonite.