28.06.2018
Doctoral Dissertation

6.7.2018 M.Sc. Roshan Budhathoki (Faculty of Mathematics and Science, Chemistry)

Time:

6.7.2018 12:00 — 15:00


Location: Ylistonrinne , KEM4
Release: Phosphorus recovery from the biomass ash
Recovery of phosphorus from solid ash residues is seen as one of the conservation methods that assist to mitigate the threat for supply of affordable phosphorus.

Phosphorus (P), a biocritical element and a macronutrient for plants, is depleting from nature due to rapid mining of naturally occurring phosphate minerals. The demand for phosphorus is predicted to increase by 50-100 % by 2050 due to escalating food and feed demands for growing global population. Therefore, the supply of affordable phosphorus is at great risk and various phosphorus conservation methods, including recycling and recovery from secondary sources, are needed for its sustainability.

Challenges in waste management
Share of renewable resources, including forest biofuel, is increasing in energy sector for cogeneration of heat and electricity via CHP (combined heat and power) technology. As a result, solid ash residues are produced and create challenges in waste management. However, ash residues consist of phosphorus from 0.5 to 5.7 % by weight and can be used as a potential secondary resource for phosphorus recovery. This facilitates to solve two problems at once; phosphorus sustainability and waste management.

In his doctoral dissertation in chemistry, Roshan Budhathoki developed methods for production of pure phosphate compounds with higher value and usability from highly heterogeneous fly ash with high concentration of impurities. Various hydrometallurgical methods including beneficiation, desilication, ion exchange and precipitation were employed to procure high-grade phosphate products. However, the techniques employed herein can be applied to recover phosphorus from other solid ash residue, e.g., sludge ash.

- We showed that particle size based beneficiation is a feasible option to increase the phosphory content in the fly ash samples. Also removal of silicon and iron facilitates to precipitate high-grade aluminium phosphate and aluminium phosphate is converted into struvite, a slow releasing fertilizer, via a green approach that uses less acid reagents,says Roshan Budhathoki.

Budhathoki’s work emphasizes on conversion of fly ash derived biomass into high-grade phosphate products. However, the techniques employed herein can be applied to recover phosphorus from other solid ash residue, e.g., sludge ash. Recovery of phosphorus from solid ash residues is seen as one of the conservation methods that assist to mitigate the threat for supply of affordable phosphorus.

M.Sc. Roshan Budhathoki defends his doctoral dissertation in Chemistry “Beneficiation, desilication and selective precipitation techniques for phosphorus refining from biomass derived fly ash” on 6th of July 2018 at 12:00 in KEM4. Opponent Assistant Professor Mari Lundström (Aalto University) and custos Docent Ari Väisänen (University of Jyväskylä).The doctoral dissertation is held in English.

Roshan Budhathoki completed his bachelor’s degree in chemistry from Tri-Chandra College, Nepal in 2009 and master’s degree in renewable energy with major in chemistry from University of Jyväskylä in 2013.

For more information:

The dissertation is published in the series Department of Chemistry, University of Jyväskylä Research Report No. 209, 64 p., Jyväskylä 2018, ISSN: 0357-346X, ISBN 978-951-39-7500-5. It is available at the University Library’s Publications Unit, tel. +358 (0)40 805 3825, myynti@library.jyu.fi. Link to thesis: https://jyx.jyu.fi/handle/123456789/58756?locale-attribute=fi

More information

Roshan Budhathoki

roshan.budhathoki@jyu.fi