Identifiability study of the proteins degradation model, based on ADM1, using simultaneous batch experiments

The objective of the present study is to analyse kinetic and stoichiometric parameter values of
gelatine anaerobic degradation at thermophilic range, based on an experiment designed to elucidate if
volatile fatty acids (VFA) are inhibitors of the hydrolysis process. Results showed that VFA are not inhibiting
the hydrolysis process. The ADM1 model adequately expressed the consecutive steps of hydrolysis and
acidogenesis, with estimated kinetic values corresponding to a fast acidogenesis and slower hydrolysis. The
hydrolysis was found to be the rate limiting step of anaerobic degradation. Estimation of yield coefficients
based on the relative initial slopes of VFA profiles obtained in a simple batch experiment produced
satisfactory results. From the identification study, it was concluded that it is possible to determine univocally
the related kinetic parameter values for protein degradation if the evolution of amino acids is measured in
simultaneous batch experiments, with different initial protein and amino acids concentrations.