The design of industrial symbiosis: An input-output approach

Industrial symbiosis (IS) has gained more attention in the production economics as the pressure on companies increases for the reduction of waste emissions and primary resources consumption. In fact, this has forced companies to provide other companies their wastes as primary resources and vice-versa. These supply circles lead to IS that can mitigate environmental impacts and costs in industrial areas (IA). The aim of this paper is to provide guidelines for the future evolution of IA operating on the basis of IS principles. Given a production network within an IA, perfect IS within the network is defined as a theoretical optimum for IS design where no primary resources is needed from outside and no wastes are discharged outside. Adopting an enterprise input-output approach, the conditions for a perfect IS are found for one-waste and multi-waste cases, and the distance between the states of the actual network and of the related perfect IS is measured. Proposed approach is empirically applied to Santa Croce sull'Arno industrial district of tannery where the recycling of chrome liquors, fleshing, and wastewater are investigated. Results show under which conditions perfect symbiosis is achievable for two waste types. Policy implications are also suggested for the design of IA when IS principles are adopted.