Life cycle assessment of emissions in construction and operation phases of liquid swine manure management technologies

Aerobic composting (AC), anaerobic digestion (AD), and anaerobic manure storage tank (AMST) are conventional systems for treating liquid swine manure (LSM). In this study, life cycle assessment (LCA) was used to evaluate environmental impact in both construction and operation phases to compare AC, AD, and AMST systems. The results were obtained using SimaPro(& REG;) with ReCiPe impact assessment method. The system boundary was from cradle to grave, and the adopted functional unit was 10.0 m(3) of LSM. LCA results showed that steel and cement were the inputs with higher environmental impact in construction phase in AC and AD with average percentages of 74.25 and 24.56%, and 57.17 and 17.30%, respectively. For AMST, high-density polyethylene (HDPE) was more significant with average impact of 83.37%. The comparison between the construction and operation phases of each system individually showed that the construction causes the higher impact in AC and AD, while in AMST was the operation phase. The comparison between the construction phases of the systems showed that AC resulted in higher environmental impacts than in AD and AMST in all impact categories. In relation to operation phase, AMST system causes higher impact compared to AD and AC. Finally, the global comparison of systems showed that the AD with energy use has the better environmental performance. The high use of steel and cement in construction phase and methane production in operation phase have a significant impact on the global life cycle.