Impact of waste slag reuse on the sustainability of the secondary lead industry evaluated from an emergy perspective

Abstract

Waste slag (WS) derived from the pyrometallurgical process of waste lead-acid battery (LAB) is becoming a potential contributor to environmental pollution. Therefore, WS treatment or disposal should be considered an integral part of waste LAB treatment systems to comprehensively analyze the sustainability of secondary lead industry. Given that emergy analysis (EmA) can evaluate all forms of energy, materials, and human services on a common basis by converting them into equivalents of one form of energy, our study proposes an emergy-based approach and several improved indicators. Unlike traditional emergy indicators, the output emergy and waste emergy in our approach were added into an improved emergy indicators. The improved indicators also converted emission impacts into equivalent emergy associated with economic activities, including the emergy of ecological services, emergy loss of affected natural resources, emergy losses associated with human health damage and land occupation. Next, four scenarios as study cases were evaluated using the proposed approach and indicators. Our study found that 1) the improved emergy indicators are more rigorous than their traditional counterparts; 2) although the reuse of WS raises the disposal costs (scenario C and scenario D), it can improve the environmental performance of waste LAB treatment systems, thereby greatly improving system sustainability; finally, the proposed approach can help policy-makers make decisions and guide enterprises to improve the overall performance of waste LABs treatment systems.