Theoretical methane production generated by the co-digestion of organic fraction municipal solid waste and biological sludge

• Co-digestion of OFMSW and biological sludge could improve economics and productivity.
• Prediction methodologies give an indication of maximum methane productivity.
• Kinetics of the co-digestion could be obtained with Gompertz and First order models.
• COD, elemental and organic composition could be useful to predict methane potentials.
• Gompertz model determine productivities and kinetics within the 7th day of experiment.

The co-digestion of two problematic and available wastes, namely Organic Fraction Municipal Solid Waste (OFMSW) and biological sludge, was carried out in this work. Biochemical Methane Potential (BMP) tests are a useful tool for determining the best substrate and co-digestion configurations, however there are some methodologies destined to save costs and time from this process by using the theoretical final methane potential of a substrate from its organic composition. Besides there are some models capable not only of reproducing the methane curve behavior, but also of predicting final methane productions from the first days of experimentation. Methodologies based in the elemental composition for the determination of theoretical production fit better with the experimental results and behavior, nevertheless the Gompertz model was capable of predicting the final productivity within the 7th day of experiment, selecting at the same time the co-digestion of 80% OFMSW and 20% Biological sludge as the optimum.