Macroscopic and microscopic variation in recovered magnesium phosphate materials: Implications for phosphorus removal processes and product re-use

Massey, M.S. and Ippolito, J.A. and Davis, J.G. and Sheffield, R.E. (2009) Macroscopic and microscopic variation in recovered magnesium phosphate materials: Implications for phosphorus removal processes and product re-use. Bioresource Technology. 101:877-885.

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Abstract

Phosphorus (P) recovery and re-use will become increasingly important for water quality protection and
sustainable nutrient cycling as environmental regulations become stricter and global P reserves decline.
The objective of this study was to examine and characterize several magnesium phosphates recovered
from actual wastewater under field conditions. Three types of particles were examined including crystalline
magnesium ammonium phosphate hexahydrate (struvite) recovered from dairy wastewater, crystalline
magnesium ammonium phosphate hydrate (dittmarite) recovered from a food processing facility,
and a heterogeneous product also recovered from dairy wastewater. The particles were analyzed using
‘‘wet” chemical techniques, powder X-ray diffraction (XRD), and scanning electron microscopy in conjunction
with energy dispersive X-ray spectroscopy (SEM–EDS). The struvite crystals had regular and
consistent shape, size, and structure, and SEM–EDS analysis clearly showed the struvite crystals as a surface
precipitate on calcium phosphate seed material. In contrast, the dittmarite crystals showed no evidence
of seed material, and were not regular in size or shape. The XRD analysis identified no crystalline
magnesium phosphates in the heterogeneous product and indicated the presence of sand particles. However,
magnesium phosphate precipitates on calcium phosphate seed material were observed in this product
under SEM–EDS examination. These substantial variations in the macroscopic and microscopic
characteristics of magnesium phosphates recovered under field conditions could affect their potential
for beneficial re-use and underscore the need to develop recovery processes that result in a uniform, consistent
product.

Item Type:	Article
NWISRL Publication Number:	1315
Subjects:	Manure Animal Manure > Chemistry
Depositing User:	Users 6 not found.
Date Deposited:	30 Nov 2009 21:59
Last Modified:	17 Oct 2016 15:50
Item ID:	1338
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1338