Struvite-based fertilizer and its physical and chemical properties

Abstract

This study describes a method to formulate struvite fine powder into pellets that are easy to spread on agricultural land. To evaluate the quality of produced pellets, some chemical and physical properties commonly measured for fertilizers were tested. The findings indicated that the salt index and heavy metal content of struvite pellets were significantly lower than those of commercial NPK fertilizers. In addition, the percentage of nutrient released from struvite pellets after 105 days was in the range of 9.6–23.2, 8.4–26.7 and 11.3–32.6% for nitrogen, phosphorous and magnesium, respectively, which is considerably lower than that of commercial NPK fertilizer. Among different formulations between struvite crystals and binders, starch and bentonite were the most efficient in agglomerating struvite powder, leading to an increase in the crush strength to over the recommended limit of>2.5 kgf for fertilizer hardness.

Keywords:

• fertilizer
• struvite
• pellet
• magnesium ammonium phosphate hexahydrate
• physical properties
• chemical properties

Acknowledgements

Swedish Energy Agency is gratefully acknowledged for the financial support that made this study possible.