Both groups of acidogenic and methanogenic organisms are different with respect to their nutritional requirements, physiology, pH optima, growth, and nutrient uptake kinetics, and their ability to withstand environmental stress factors [13]. With conventional digestion processes, by combining acidogens and methanogens in one reactor, uniform conditions are imposed on both groups. However, two-phase anaerobic digestion implies a process configuration employing separate reactors for acidification and methanogenesis connected in series, allowing optimisation of both processes