Modeling herbivorous animal digestive system as 3- continuous stirred tank reactor (CSTR) and 1-plug flow reactor (PFR) in series with specific reference to Hippopotamus amphibious

Herbivores contain microflora in their guts which digest lignocellulosics in their stomachs and intestines by secreting the essential enzymes that perform the function so efficiently that the guts of these animals have been described as the best fermentation tanks known. Hippopotamus amphibious , a herbivorous animal, has three stomach compartments together with small and large intestines which are of similar structure and function. This work models each stomach compartment as continuous stirred tank reactor (CSTR) and the small and large intestines as plug flow reactor (PFR) arrangements in series in order to determine the performance of the herbivorous digestive system. Autocatalytic microbial fermentation takes place in the stomach, modeled as CSTR and described by Monod kinetics, whereas enzymatic digestion takes place in the intestines, modeled as PFR and described by Michaelis Menten equation. Designed equations derived from the two equations are used for the reactor sizing of the modeled reactors. This shows the efficiency of each reactor at converting the purely lignocellulosics substrates to useful products like protein, vitamin, fatty acid and the bye-products. The results showed that 3CSTR-IPFR model is the best and most efficient for converting lignocellulosics. Keywords: Lignocellulosics, microflora, herbivore, catalytic, reactor