Interpretation of material flow analysis results and a case study on cleaner production for wastewater source reduction in a zinc electrolysis cellhouse

Abstract With the intensification of ecological and environmental problems due to increasing demand for resources, cleaner production (CP) is required to improve the production system for simultaneous resource conservation and environmental protection especially in the heavy pollution industries. Material flow analysis (MFA) is an effective way to investigate the causes of system problems, and however, interpretation of MFA results is one of the difficulties to convey meaningful information to CP decision makers. In this paper, a new evaluation method is proposed to interpret the results of MFA for CP implementation. Based on the concentration/dilution characteristics of the substance, two novel indicators ( S and Δ S ) were devised to quantify the hazardous potential and the resource potential of the flows, respectively, for CP opportunities identification and CP strategies selection. The evaluation method in combination with MFA is applied to the wastewater reduction in zinc electrolysis cellhouse. Results showed that in comparison with traditional indicators based on mass unit, S and Δ S integrated various dimensions of flow properties into single feature, which enabled comparing the quantity and quality of different zinc flows in a straightforward way. The two indicators are highly sensitive to the changes of the processes in the micro-scale material flow system, and are informative in CP decision-making by linking up the flow features with subsequent CP actions. The reduction potential of 97.3% of zinc emission and 70.6% of fresh water consumption in the case study was indicated by the evaluation and further validated by the implementation of CP in practice. Results demonstrated the effectiveness of the evaluation method to improve the transparency of the material transformation/transfer in MFA and the advantages to better identify the underlying structure of CP strategy decision problem especially when the target substance serves as both resource and pollutant.