The potential for livestock manure valorization and phosphorus recovery by hydrothermal technology - a critical review

Carbon neutrality has become one of the major challenges to the global sustainable development. The sector of livestock & manure, which accounts for 5.8% of greenhouse gas emissions, has attracted worldwide attentions. The implemention of sustainable technologies is considered an important step towards achieving the carbon reduction in livestock & manure sector. In this work, the recent trends in the potential for livestock manure valorization and phosphorus (P) recovery by hydrothermal technology were systematically studied. First of all, the current situation of livestock manure treatment and waste P utilization at domestic and international level were reviewed. The strengths and challenges of several technical means of livestock manure resource utilization, include composting, anaerobic digestion, and thermochemical conversion, were discussed. Then, the research advance of hydrothermal technology for P utilization and two techniques, include precipitation and adsorption methods, were summarized. Finally, the research perspective of waste P utilization was covered. This review provides the critical strategy for the utilization of livestock manure and waste P resource. Future research priorities in the sustainable management of carbon neutrality in these settings are also proposed.