Anaerobic acidogenic fermentation with high-solid sludge is a promising method for volatile fatty acid(VFA) production to realize resource recovery. In this study, to model inhibition by free ammonia in high-solid sludge fermentation, the anaerobic digestion model No. 1(ADM1) was modified to simulate the VFA generation in batch, semicontinuous and full scale sludge. The ADM1 was operated on the platform AQUASIM 2.0.Three kinds of inhibition forms, e.g., simple inhibition, Monod and non-inhibition forms,were integrated into the ADM1 and tested with the real experimental data for batch and semi-continuous fermentation, respectively. The improved particle swarm optimization technique was used for kinetic parameter estimation using the software MATLAB 7.0. In the modified ADM1, the Ksof acetate is 0.025, the km,acis 12.51, and the KI_NH3is 0.02,respectively. The results showed that the simple inhibition model could simulate the VFA generation accurately while the Monod model was the better inhibition kinetics form in semi-continuous fermentation at p H 10.0. Finally, the modified ADM1 could successfully describe the VFA generation and ammonia accumulation in a 30 m3full-scale sludge fermentation reactor, indicating that the developed model can be applicable in high-solid sludge anaerobic fermentation.
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