Swine manure is an alternative to synthetic fertilizer for increasing crop production as it contains valuable recyclable nutrients (NH4+-N and ortho-PO43- P). However, it poses several environmental problems when disposed of or used improperly. In this study, we report the efficacy of a nutrient recovery scheme from swine manure using biochar and biochar-zeolite mixtures. Here, we evalauted: (1) two biochars- Fe-modified (Fe-BC) and unmodified (U-BC) corn stover biochars produced by autothermal fast pyrolysis; and (2) zeolite with a SiO2/Al2O3 ratio of 30:1. Results showed that both biochars can effectively recover manure NH4+-N (215 mg g-1 and 209 mg g-1 for Fe-BC and U-BC, respectively) and ortho-PO43- P (33.2 mg g-1 and 29.3 mg g-1 for Fe-BC and U-BC, respectively). The addition of zeolite to biochar increased the NH4+-N removal efficacy from manure by 38% and 28% for the Fe-BC and U-BC, respectively. The mixture of U-BC and zeolite experienced nitrogen breakthrough faster than the mixture of Fe-BC and zeolite. Desorption study and surface analyses showed that in addition to Fe, the presence of divalent Mg in swine manure effectively sorbed P at the working pH, which precipitated on the biochar at overloaded manure concentrations. This study reveals that the biochar-zeolite mixtures could be the basis for an integrated recycling system to recover N and P from swine manure.

Using biochar and zeolite to recycle phosphorus and nitrogen from swine manure: An integrative approach

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