Development of optimization model for livestock manure disposal system taking into account of supply-demand balance for recycled products

We developed a simulation model for optimizing the efficient use of livestock manure system taking into account of supply-demand balance of fertilizer. This model made it possible to calculate the most effective combination of livestock manure disposal systems and fertilizer transportation systems to minimize the total cost of disposal for a given maximum permitted total GHG emission from disposal and transportation systems. In this study, we proposed an efficient use system of livestock manure by using this optimization model in Iwate Prefecture. The result of the simulation indicated that manure heaped in a field should be utilized as a fertilizer to reduce GHG emission because GHG increase from disposal system and fertilizer transportation was less than GHG reduction by elimination of field heaping and decrease in the usage of chemical fertilizer. And a result of sensitivity analysis to variables in the optimization model for livestock manure disposal system showed that the fluctuations of compost and woodchip price, and manure emission style of especially beef cow and pig strongly influenced on the optimal selection of disposal technology rather than that of electricity price.