Composting optimization: Integrating cost analysis with the physical-chemical properties of materials to be composted

Composting can bring reductions in the cost of disposing of organic by-products and residues, as well as providing an income, since composts can possess chemical-physical properties of considerable interest for use as a soil improver. This study identifies in detail the types of chemical-physical as well as economic constraints that recur in composting mixture design and their mathematical formulations are generalized; a method for composting optimization has then been developed, through the implementation of a mathematical model and by defining the functional characteristics of a software application, which take into account simultaneously the economic variables, the physical-chemical properties and the operational constraints, required for a good start of the composting processes. This method allows processing costs to be reduced as much as possible in relation to all the physical-chemical parameters that ensure a high quality of the mixture to be composted will be obtained. The aim is to make this method effectively usable in actual compost production conditions involving large amounts of organic materials to be treated, a multiplicity of variables to be taken into account, very narrow profit margins, and the need to take certain decisions quickly. Through some application examples, it is shown how the model developed has made it possible to reduce the variable costs for preparation of the composting mixtures, while obtaining the right physical-chemical characteristics so that the process can start properly and proceed.