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Driving forces and barriers in the removal of phosphorus from water using crop residue, wood and sewage sludge derived biochars

Driving forces and barriers in the removal of phosphorus from water using crop residue, wood and sewage sludge derived biochars
Driving forces and barriers in the removal of phosphorus from water using crop residue, wood and sewage sludge derived biochars

The removal of phosphorus (P) from sewage effluents is necessary to control eutrophication in receiving waters. Biochar has been proposed and is investigated for the capture and reuse of P, however the forces driving and limiting P adsorption are still largely unclear. To identify the forces governing P uptake by biochar, biochars with markedly different physicochemical characteristics derived from a variety of biomass (oilseed rape straw, wheat straw, miscanthus straw, rice husk, soft wood and sewage sludge residue), pyrolysed at various temperatures, were investigated. The biochar samples were characterised in terms of pH, electrical conductivity, total acidity, carbon chemistry, metal composition, surface area , and porosity, and the uptake and release of P was compared to the biochar properties using multivariate analysis. Uptake of P by the biochars as such was low (< 0.71 mg P/g biochar with feed solutions of 50 mg P/l) and, among the variables studied, the biochars' Ca and Mg content was key in P removal and found to be pH dependant. Enhancement of biochar surface area and porosity was carried out by activation with CO 2 at 800 °C and the uptake significantly improved (p < 0.05) (i.e. an increased surface area from <20 m 2 /g up to 781 m 2 /g gave a limited improvement in P removal to <1.2 mg P/g biochar at feed level of 50 mg P/l). These results confirm that the potential to use these unmodified biochars derived from a variety of biomass for P sorption is low, but that the material provides properties that may be modified or enhanced to increase sorption capacity. This study indicates that biochar/biochar feedstock with greater content of Ca and Mg will be more advantageous for P capture.

Biochar, Characterisation, P removal, Pyrolysis
0048-9697
623-631
Melia, Patrick M.
be45abd6-6cb7-40c5-b0fe-6c74b5b9cc24
Busquets, Rosa
d3f8511d-c34e-4bf7-956c-19e4c1c5949f
Hooda, Peter S.
e0e628c5-d7dd-49b1-9bd7-3b4e96c78e91
Cundy, Andrew B.
994fdc96-2dce-40f4-b74b-dc638286eb08
Sohi, Saran P.
a595774e-b59d-4aa2-b556-1c698361d000
Melia, Patrick M.
be45abd6-6cb7-40c5-b0fe-6c74b5b9cc24
Busquets, Rosa
d3f8511d-c34e-4bf7-956c-19e4c1c5949f
Hooda, Peter S.
e0e628c5-d7dd-49b1-9bd7-3b4e96c78e91
Cundy, Andrew B.
994fdc96-2dce-40f4-b74b-dc638286eb08
Sohi, Saran P.
a595774e-b59d-4aa2-b556-1c698361d000

Melia, Patrick M., Busquets, Rosa, Hooda, Peter S., Cundy, Andrew B. and Sohi, Saran P. (2019) Driving forces and barriers in the removal of phosphorus from water using crop residue, wood and sewage sludge derived biochars. Science of the Total Environment, 623-631. (doi:10.1016/j.scitotenv.2019.04.232).

Record type: Article

Abstract

The removal of phosphorus (P) from sewage effluents is necessary to control eutrophication in receiving waters. Biochar has been proposed and is investigated for the capture and reuse of P, however the forces driving and limiting P adsorption are still largely unclear. To identify the forces governing P uptake by biochar, biochars with markedly different physicochemical characteristics derived from a variety of biomass (oilseed rape straw, wheat straw, miscanthus straw, rice husk, soft wood and sewage sludge residue), pyrolysed at various temperatures, were investigated. The biochar samples were characterised in terms of pH, electrical conductivity, total acidity, carbon chemistry, metal composition, surface area , and porosity, and the uptake and release of P was compared to the biochar properties using multivariate analysis. Uptake of P by the biochars as such was low (< 0.71 mg P/g biochar with feed solutions of 50 mg P/l) and, among the variables studied, the biochars' Ca and Mg content was key in P removal and found to be pH dependant. Enhancement of biochar surface area and porosity was carried out by activation with CO 2 at 800 °C and the uptake significantly improved (p < 0.05) (i.e. an increased surface area from <20 m 2 /g up to 781 m 2 /g gave a limited improvement in P removal to <1.2 mg P/g biochar at feed level of 50 mg P/l). These results confirm that the potential to use these unmodified biochars derived from a variety of biomass for P sorption is low, but that the material provides properties that may be modified or enhanced to increase sorption capacity. This study indicates that biochar/biochar feedstock with greater content of Ca and Mg will be more advantageous for P capture.

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Accepted Manucript_STOTEN_Melia et al_2019
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More information

Accepted/In Press date: 15 April 2019
e-pub ahead of print date: 16 April 2019
Published date: 20 July 2019
Keywords: Biochar, Characterisation, P removal, Pyrolysis

Identifiers

Local EPrints ID: 431066
URI: https://eprints.soton.ac.uk/id/eprint/431066
ISSN: 0048-9697
PURE UUID: 236ee5dc-cc25-496e-96fe-31091162d545
ORCID for Andrew B. Cundy: ORCID iD orcid.org/0000-0003-4368-2569

Catalogue record

Date deposited: 22 May 2019 16:30
Last modified: 23 Jul 2019 00:30

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Contributors

Author: Patrick M. Melia
Author: Rosa Busquets
Author: Peter S. Hooda
Author: Andrew B. Cundy ORCID iD
Author: Saran P. Sohi

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