Investigating effects of phosphogypsum disposal practices on the environmental performance of phosphate fertilizer production using emergy analysis and carbon emission amounting: A case study from China

The phosphate fertilizer industry faces increasing environmental pressures related to phosphogypsum disposal. It is necessary to explore the impact of different phosphogypsum disposal schemes on the comprehensive performance to promote sustainable development in this industry. We propose a comprehensive approach based on emergy analysis and carbon emission accounting to compare the impacts of different phosphogypsum disposal schemes on phosphate fertilizer production in terms of environmental sustainability, pollutant emission impacts, carbon emission intensity, and their synergistic effects. As a case study, a monoammonium phosphate production enterprise (phosphogypsum storage, Scenario 1) in Hubei Province and three other scenarios based on different phosphogypsum resource utilization practices (Scenario 2: monoammonium phosphate production + phosphogypsum manufacturing building materials; Scenario 3: monoammonium phosphate production + phosphogypsum manufacturing fertilizer filling materials; and Scenario 4: monoammonium phosphate production + phosphogypsum manufacturing cement retarder) were investigated using the proposed approach. The results show that the three phosphogypsum resource utilization practices could enhance the synergistic effect of the integrated system to different degrees relative to Scenario 1 by improving the energy-use efficiency and/or reducing the impact of pollutant emissions. Scenario 3 had the best synergistic effect, followed by scenarios 4, 2, and 1. The three phosphogypsum reuse practices enhanced carbon emission intensity to varying degrees compared with Scenario 1 due to the increasing fossil energy use. Those phosphogypsum reuse practices, based on nonrenewable resources/energy source inputs, caused conflict between waste reduction and carbon emission reduction. This study helps construct an integrated approach for thoroughly investigating the environmental performance of an integrated system consisting of phosphate fertilizer production and phosphogypsum disposal, thus providing a decision-making tool for the phosphate fertilizer industry. We also present targeted decisionmaking information for phosphate fertilizer production in China.