Crop fertilisation potential of phosphorus in hydrochars produced from sewage sludge.

Autor: McIntosh S; Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia. Electronic address: Shane.mcintosh@scu.edu.au., Padilla RV; Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia., Rose T; Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia., Rose AL; Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia., Boukaka E; Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia., Erler D; Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2022 Apr 15; Vol. 817, pp. 153023. Date of Electronic Publication: 2022 Jan 11.
DOI: 10.1016/j.scitotenv.2022.153023
Abstrakt: Sewage sludges are a rich underused source of phosphorus (P) which contributes to environmental degradation, yet if recaptured, could return significant amounts of P to agricultural systems. Hydrothermal carbonisation (HTC) can efficiently recover P, with the added ability to transform P species into potentially more desirable forms for direct application to crops. P dynamics in hydrochars have primarily examined P speciation and chemical extractability as indicators of P bioavailability, but few studies directly evaluate the agronomic effectiveness of hydrochars as P fertilisers. As such, there is a clear need to assess the suitability of hydrochar as a source of bioavailable P in plant systems and the influence of HTC synthesis conditions. Response Surface Modelling of HTC synthesis conditions (pH, temperature and time), revealed initial pH significantly influence P distribution. Mild conditions of 180 °C for 30 min at pH 8.0 maximised P recovery (99%) along with carbon (62%) and nitrogen (43%) in hydrochars. Systematic characterisation of hydrochar P by chemical extraction and P L 2,3 -edge X-ray absorption near edge spectroscopy revealed H 2 O, NaHCO 3 and NaOH- P fractions were significantly (p < 0.05) reduced in all hydrochars, while HCl-P fraction increased with HTC temperatures at pH 7. In contrast, P L 2,3 -edge XANES spectra were remarkably similar in raw sludges and corresponding hydrochars, regardless of HTC temperature or pH, revealing P was predominantly present as ferric phosphate with some hydroxyapatite. Multiple linear regression modelling suggested a significant relationship between chemical extractability and P bioavailability to wheat present in the raw sludges and hydrochars. This research provides further insight into the potential to use hydrothermal treatment for recovery and agricultural reuse of P, the importance of operational conditions on P transformation and the relationship between P speciation and bioavailability. The value of sewage sludge in a more sustainable global P cycle is also highlighted.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2022 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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