Research on the Ecological Economic Trade-off Mechanism and Synergistic Pathway of Liquid Pig Manure Treatment Technology

The resource utilization of livestock and poultry manure is crucial for improving rural ecological environments. This study employed Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCC) methods to conduct comprehensive environmental and economic evaluations of five pig liquid manure treatment approaches: conventional storage, nitrification/denitrification, ammonia stripping + struvite precipitation, membrane filtration + struvite precipitation, and ectopic fermentation bed. Results demonstrate that the ammonia stripping + struvite method achieved optimal environmental performance with the lowest global warming potential (GWP, 76.22 kg·CO₂-eq) and annual environmental costs of 130 700 yuan, whereas the ectopic fermentation bed approach exhibited the highest GWP (228.41 kg·CO₂-eq) and annual costs of 196 500 yuan. Economically, the ectopic fermentation bed generated the highest annual revenue of 778 500 yuan from organic fertilizer production, with a positive net present value (NPV = 587 500 yuan). In contrast, all three anaerobic fermentation technologies (nitrification/denitrification, ammonia stripping, and membrane filtration) showed negative NPVs due to high investment costs, indicating limited economic viability. Coupling analyses reveal that all treatment methods had cost-benefit.