Evaluating chromium coupled with carbon metabolism and environmental performance in the chromate industrial symbiosis network in China

Abstract

The pollution of toxic and carcinogenic chromium slags of the chromate industry has been a public concern and industrial symbiosis is proved to be feasible and efficient in recycling chromium slags. How to appraise and improve sustainability of chromate industrial symbiosis networks is still an open problem where functional and structural performance are key approaches to solve. This paper aims to explore chromium and carbon metabolic behavior of a chromate industrial symbiosis network with ecological network analysis at intra-firm level. Results show that industrial symbiosis reduces chromium slags emissions and improves resource utilization efficiency. Influenced by flow type and quantity, the chromium metabolism realizes mutualism but the carbon metabolism fails due to intense competition for carbon resource among the recycling processes (the aluminum hydroxide, sodium sulfide and alloy steel processes). The sodium dichromate process is the largest controller on the chromium and carbon metabolism and the sodium sulfide and alloy steel processes both rely on carbon resource support of the sodium dichromate process even to 100% which may explain the intense competition. Under disharmonious connection pattern of metabolic processes, structural defects both occur to the chromium and carbon metabolism. Even though, the chromium metabolism is closed to the stable condition while the carbon metabolism still requires more network efficiency. Overall, the combination of chromium and carbon metabolism provide more details in exploring metabolic behavior of the chromate industrial symbiosis network. The applied method may be helpful to refine management and optimization in developing industrial symbiosis.