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The function-led design of porous hydrochar from mineral-rich biowaste for environmental applications inevitably suffers from carbon–ash recalcitrance. However, a method to alter the original carbon skeleton with ash remains elusive and hinders the availability of hydrochar. Herein, we propose a facile strategy for breaking the rigid structure of carbon–ash coupled hydrochar using phase-tunable molten carbonates. A case system was designed in which livestock manure and NaHCO3 were used to prepare the activated hydrochar, and NH3 served as the target contaminant. Due to the redox effect, we found that organic fractions significantly advanced the melting temperature of Na2CO3 below 800 °C. The Na species steadily broke the carbon–ash interaction as the thermal intensity increased and transformed inorganic constituents to facilitate ash dissolution, rebuilding the hydrochar skeleton with abundant hierarchical channels and active defect edges. The surface polarity and mesopore distribution collectively governed the five cycles NH3 adsorption attenuation process. Manure hydrochar delivered favorable potential for application with a maximum overall adsorption capacity of 100.49 mg·g−1. Integrated spectroscopic characterization and theoretical computations revealed that incorporating NH3 on the carbon surface could transfer electrons to chemisorbed oxygen, which promoted the oxidation of pyridine-N during adsorption. This work offers deep insight into the structure function correlation of hydrochar and inspires a more rational design of engineered hydrochar from high-ash biowaste.

● Carbon reduction potential of manure treatment technologies was summarized.● Accounting methodologies of carbon emission and footprint of manure were analyzed.● The quote of carbon trading market at home and abroad was analyzed.● Some points for the boost of potential of manure carbon trading were advised. The rapid growth of the livestock and poultry production in China has led to a rise in manure generation, which contributes to the emissions of GHGs (greenhouse gases including CH4, N2O and CO2) and other harmful gases (NH3, H2S). Reducing and managing carbon emissions has become a critical global environmental imperative due to the adverse impacts of GHGs. Unlike previous reviews that focused on resource recovery, this work provides an unique insight of transformation from resource-oriented manure treatment to integration of resource recovery with pollution reduction, carbon accounting and trading, focusing on the sustainable development of manure management system. Considering the importance of accounting methodologies for carbon emission and trading system toward carbon neutrality society, suggestions and strategies including attaching high importance to the development of more accuracy accounting methodologies and more practical GHG emission reduction methodologies are given in this paper. This work directs the establishment of carbon reduction methodologies and the formulation of governmental policies for livestock and poultry manure management system in China.