Selectively Retaining Nutrients in Biochar by Magnesium Added Two-Zone
Staged Copyrolysis of Blue Algae and Corn Gluten
Abstract
Disposal of blue algae (BA) and corn gluten (CG) wastes and simultaneous
recovery of the abundant phosphorus (P) and nitrogen (N) by pyrolysis to
obtain biochars with high fertility is a promising strategy. However,
pyrolysis of BA or CG alone by a conventional reactor cannot reach the
target. Herein, we propose a novel MgO-enhanced N and P recovery method
by designing a two-zone staged pyrolysis reactor to highly efficiently
recover N and P with easily available plant forms in BA and CG. The
results show that a 94.58% TP retention rate was achieved by means of
the special two-zone staged pyrolysis method, in which the effective P
(Mg2PO4(OH) and R-NH-P) accounted for 52.9% of TP, while the total
nitrogen (TN) reached 4.1 wt%. In this process, stable P was formed
first at 400 ℃ to avoid rapid volatilization and then to form hydroxyl P
at 800 ℃.