Characterisation of ashes from waste biomass power plants and phosphorus recovery

Lijian Leng; Anna A Bogush; Amitava Roy; Julia A Stegemann

doi:10.1016/j.scitotenv.2019.06.312

Characterisation of ashes from waste biomass power plants and phosphorus recovery

Sci Total Environ. 2019 Nov 10:690:573-583. doi: 10.1016/j.scitotenv.2019.06.312. Epub 2019 Jun 21.

Authors

Lijian Leng¹, Anna A Bogush², Amitava Roy³, Julia A Stegemann⁴

Affiliations

¹ School of Resources, Environmental & Chemical Engineering, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang University, Nanchang 330031, China.
² Centre for Resource Efficiency & the Environment, Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK.
³ J. Bennett Johnston, Sr., Center for Advanced Microstructures & Devices, Louisiana State University, 6980 Jefferson Hwy, Baton Rouge, LA 70806, USA.
⁴ Centre for Resource Efficiency & the Environment, Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK. Electronic address: j.stegemann@ucl.ac.uk.

PMID: 31301498
DOI: 10.1016/j.scitotenv.2019.06.312

Abstract

Biowastes, such as meat and bone meal (MBM), and poultry litter (PL), are used as energy sources for industrial combustion in the UK. However, the biomass ashes remaining after combustion, which contain nutrients such as phosphorus, are landfilled rather than utilised. To promote their utilisation, biomass ashes from industries were characterised in terms of their elemental and mineral compositions, phosphorus extractability, and pH-dependent leachability. These ashes were highly alkaline (pH as high as 13), and rich in calcium and phosphorus. The P bio-availabilities in the ash evaluated by Olsen's extraction were low. Hydroxyapatite and potassium sodium calcium phosphate were identified by X-ray powder diffraction (XRD) as the major phases in the MBM and PL ashes, respectively. The leaching of P, Ca, and many other elements was pH dependent, with considerable increase in leaching below about pH 6. P recovery by acid dissolution (e.g., with H₂SO₄) seems feasible and promising; the optimized acid consumption for ~90% P recovery could be as low as 3.2-5.3 mol H⁺/mol P.

Keywords: Acid neutralization capacity; Animal manure; Fertiliser; Incineration; Phosphorus recovery.