Comparative study of electroplating sludge reutilization in China: environmental and economic performances

Harmless disposal and reutilization of electroplating sludge (ES) attract growing interests due to the high content of heavy metals, which requires economical-affordable and environmentally friendly processing technologies. Main reutilization alternatives in China, i.e., acid leaching, bioleaching, smelting, ironmaking blast furnace co-processing (IBFC), and cement kiln co-processing (CKC), were evaluated and compared via life cycle assessment (LCA) and life cycle costing (LCC) methods. In addition, the heavy metal recovery potential of these scenarios was also evaluated to focus on the sustainable use of metal resources. LCA results show that acid leaching outperforms other scenarios due to the environmental benefits originating from recovering heavy metals, while smelting exhibits the worst due to high energy consumption. The environmental contribution analysis reveals that the product nickel sulfate has a significant positive impact on acid leaching and bioleaching scenarios, and energy consumption is the key factor for smelting, IBFC, and CKC. LCC results show that bioleaching outperforms others, while CKC performs the worst because only inorganic materials are utilized. Bioleaching has the lowest externality cost while CKC has the highest. The heavy metal recovery assessment indicates that bioleaching exhibits the greatest potential with recovery rates of 99%, 99%, 93%, 96%, and 95% for Cu, Cr, Ni, Zn, and Fe, respectively. In contrast, the target heavy metal recovery rate for both acid leaching and smelting is 93%. Acid leaching and bioleaching scenarios are more advantageous from a comprehensive comparison.