2007 Volume 33 Issue 4 Pages 323-331
A kinetic model for methane fermentation of animal and kitchen waste was proposed based on the assumption that the biogas production rate is proportional to the concentration of volatile solids (VS) in the waste. The following equation for the biogas production rate was then derived from analysis of published data on a methane fermentation operation for pig manure.
−dCvs/dt = γ(4.61×1011)(exp(−7.47×104/RT))(Cvs)
The present model was also based on the following assumptions and sequence. (1) The digester was assumed to be a constant-volume batch reactor, and the integration time of the differential equation for the digester was one day. (2) The fermentation of organic waste fed on any given day was assumed to be independent of the waste previously fed into the digester. (3) The amount of waste degraded on a given day was calculated by applying the above rate equation to the residual VS of each batch of waste fed into the digester on each day within the retention time of the digester. (4) The summation of the calculated amounts of degraded waste gave the total amount of the biogas produced on the given day.
It was demonstrated that the present model could be used to predict the biogas production rate for animal waste, kitchen waste and mixtures of both types of waste during the mesophilic and thermophilic anaerobic digestion.
All the actual data used in this paper came from literature published by other researchers.
