Effects of pyrolysis and incineration on the phosphorus fertiliser potential of bio-waste- and plant-based materials

Robinson, J. S. ORCID: https://orcid.org/0000-0003-1045-4412 and Leinweber, P. (2023) Effects of pyrolysis and incineration on the phosphorus fertiliser potential of bio-waste- and plant-based materials. Waste Management, 172. pp. 358-367. ISSN 0956-053X doi: 10.1016/j.wasman.2023.10.012

Abstract/Summary

Land application of biomass materials and their products of thermal treatment (biochars and ashes) can offset the unsustainable use of soluble P fertilisers. However, few evaluations of P fertiliser potential have systematically addressed diverse biomass types with contrasting P contents. This paper evaluates the relative P fertiliser potential of four P-rich biowastes (animal bone, poultry manure, pig slurry, and a municipal sewage sludge) and three low-P, plant-based materials (reeds [Phragmites australis L.], rice husks [Oryza sativa L.] and cocoa prunings [Theobroma cacao L.]) and their biochars and ashes. We utilised three complementary approaches: P extractability in single solvents (2% formic and citric acids, and 1 M neutral ammonium citrate); sequential chemical P fractionation, and P dissolution/desorption kinetics. In most cases, pyrolysis and incineration of the P-rich biowastes increased P extractability (% TP) in the single solvents, whilst decreasing water-soluble P. For pig slurry, for example, pyrolysis reduced water-soluble P 20-fold, with corresponding increases observed not only in the solvent-extractable P but also in the pool of potentially plant available, NaHCO3-Pi fraction (e.g., 17 to 35% TP). These complementary datasets were also evident for the low-P feedstocks and thermal products; e.g., pyrolysis increased the NaHCO3-Pi fraction in reed feedstock from 6 to 15% TP. For all biomass feedstocks, biochars and ashes, pseudo-second order P-release kinetics provided the best fit with the experimental data. The data demonstrate scope for using pyrolysis to upgrade the P fertiliser value of a wide range of biomass materials whilst reducing their environmental impact.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/119267
Identification Number/DOI	10.1016/j.wasman.2023.10.012
Refereed	Yes
Divisions	Science > School of Archaeology, Geography and Environmental Science > Department of Geography and Environmental Science
Publisher	Elsevier
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