ANAEROBIC DIGESTION OF CHEESE WHEY USING SWINE MANURE ANAEROBIC SLUDGE AT DIFFERENT INOCULUM-SUBSTRATE RATIOS

Abstract

Introduction:
Anaerobic digestion of cheese whey is a very attractive and widely used technology, although strategies are needed to counteract the rapid whey acidification, which causes a pH dismiss and subsequent failures.
Objective:
To evaluate cheese whey anaerobic digestion using anaerobic pig manure sludge as inoculum, as well as the influence of different inoculum-substrate relationships and the reaction kinetics in each case.
Materials and Methods:
Inoculum and serum characterization was carried out in the UNISS laboratories according to standard methods; 2 L batch reactors were used to determine methane yield at three inoculum-substrate ratios (1:1, 2:1 y 3:1).
Results and Discussion:
It is possible to degrade this serum with the pig manure inoculum in the first 24-48 hours, although the potential of contained methane is not reached, due to the necessary prior inoculum adaptation and the inhibition implied by the substrate acidity. Reactors with a 3:1 substrate- inoculum ratio showed the highest methane yield (191LNCH4kgVS-1). Kinetic analysis revealed that the Hill model was the best fit, although the fit of all the experimented models allows predicting the methane yield.
Conclusions:
This work demonstrates that it is possible to use anaerobic pig manure sludge to start bioreactors that treat cheese whey, and the Hill model can be used to predict methane formation.