The MELiSSA Pilot Plant integration phase is about to start. As a first step, compartments CIVa (which is composed of a cyanobacteria named Arthrospira platensis) and CV (the "crew" compartment, simulated by rats) will be connected in the gas phase. That means that the rats will consume the oxygen generated by the cyanobacteria and the cyanobacteria will consume the CO2 coming from the rats, everything in a closed loop. This integration step will start probably by January 2015 and will last for about three months. The main objective of this MSc thesis is to simulate the experiment above. Simulations on this process would be interesting to analyse the models and conditions before the experiment takes place, to foresee how the system will behave when both compartments are connected. Also, once the experiment is done, experimental data will be analysed and compared to the previously simulated model. This analysis could eventually lead to an improved simulation model, which could be used to enhance the existent process and to serve as a basis for the modelling of the whole system.