You can try general chemical process simulators such as aspen plus and hysys (commercial), coco, emso, dwsim (free). It also depends on how much info you have about your system, that will be important in choosing the type of reactor model (kinetic, equilibrium, gibbs).
SIMBA#biogas is a powerful biogas plant simulation software, which offers all components needed for a sound analysis of wet digestion biogas plants. ... The biokinetic model is based on a modified version of the Anaerobic Digestion Model No. 1 (ADM1) of the International Water Association (IWA).
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SIMBA#biogas is a powerful biogas plant simulation software, which offers all components needed for a sound analysis of wet digestion biogas plants. SIMBA#biogas was specifically developed for modeling and dynamic simulation of wet digestion biogas plants (e.g. for agricultural and solid waste).
The SIMBA#biogas process simulator includes explicit reactor models and a dynamic digestion model capable of handling multiple substrates. The biokinetic model is based on a modified version of the Anaerobic Digestion Model No. 1 (ADM1) of the International Water Association (IWA). The corresponding influent models are pre-configured for standard agricultural wastes but can easily be adapted to your specific substrates.
SIMBA#biogas allows the realization of a wide range of applications in engineering practice, research, and education. This includes design and optimization of biogas plant layouts and connected unit processes. The full process control library known from other SIMBA# packages is also available for SIMBA#biogas and enables the user to development tailored process control concepts.