Horizontal fluxes
The horizontal fluxes consist of the carbon exchanges between the urban system and the municipal solid waste management system, including the following elements: (i) direct horizontal fluxes, consisting of transportation of the municipal solid waste generated from the urban inhabitants to the MSWM system, transportation of the compost produced from organic waste to urban green land, and transportation of the regenerated materials (paper, plastic, rubber, concrete, etc.); and (ii) indirect horizontal fluxes, consisting of the fossil fuel consumed for collecting, transporting, treating and disposing of the MSW.