The Utilization of Phosphogypsum as a Sustainable Phosphate-Based Fertilizer by Aspergillus niger

Abstract

Phosphogypsum (PG) is a by-product of the phosphorus (P) chemical industry, and usually contains ~2% residual phosphate. The P in PG would cause P pollution in the environment by the way of long-term stacking. Phosphate-solubilizing fungi (PSF) can effectively promote the release of P from insoluble phosphate. The aim of this study was to investigate the P release capacity between tricalcium phosphate (TCP) and PG by Aspergillus niger (ANG) via flask experiment. At the same time, the application of PG fertilizer (PGF) in soil was also performed. The dry biomass of ANG between TCP and PG treatment reached the maximum value of 0.71 and 0.38 g, respectively, after five days of incubation. The maximum P concentrations released from PG and TCP by ANG is five and seven days, i.e., 128 and 1103 mg/L, respectively. PG has a similar P release ratio compared with TCP by ANG, i.e., 52% vs. 55%. In the soil incubation experiment, PGF can significantly increase the soil available P content and continuously maintain the high concentration (17.2 mg/kg) after four weeks of incubation. The utilization of PG by ANG via the PGF is a feasible pathway to increase the soil P content, especially for the sustainable use of phosphate resources.