Simultaneous amorphous silica and phosphorus recovery from rice husk poultry litter ash

The livestock sector is one of the most important sectors of the agricultural economy due to an increase in the demand for animal protein. This increase generates serious waste disposal concerns and has negative environmental consequences. Furthermore, the food production chain needs phosphorus (P), which is listed as a critical raw material due to its high demand and limited availability in Europe. Manure contains large amounts of P and other elements that may be recycled, in the frame of circular economy and zero waste principles, and reused as a by-product for fertilizer production and other applications. This paper focuses on the extraction and recovery of amorphous silica from rice husk poultry litter ash. Two different extraction procedures are proposed and compared, and the obtained silica is characterized. This work shows that amorphous silica can be recovered as an almost pure material rendering the residual ash free of P. It also addresses the possibility of more specific phosphorous extraction procedures via acid leaching.

Automated summary

The livestock sector faces serious waste disposal and environmental consequences, with manure containing large amounts of phosphorus and other elements that can be recycled. This paper focuses on the extraction and recovery of amorphous silica from rice husk poultry litter ash, showing that almost pure silica can be recovered, rendering the residual ash free of phosphorus. It also discusses the possibility of more specific phosphorous extraction procedures.