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Efficient Removal of Phosphate, Nitrate, and Ammonia from Wastewater Using Unmodified Woodchip Biochar
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Mohamed Ali Wahab
Water, Volume: 18, Issue: 2, Start page: 211
Swansea University Author:
Chedly Tizaoui
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© 2026 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.
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DOI (Published version): 10.3390/w18020211
Abstract
Excess nutrients in wastewater pose significant environmental risks, highlighting the need for low-cost treatment strategies that enable their removal. This study evaluated the adsorption capacity of woodchip biochar, a widely available waste material, for phosphate (PO43−), nitrate (NO3−), and ammo...
| Published in: | Water |
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| ISSN: | 2073-4441 |
| Published: |
MDPI AG
2026
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa71332 |
| Abstract: |
Excess nutrients in wastewater pose significant environmental risks, highlighting the need for low-cost treatment strategies that enable their removal. This study evaluated the adsorption capacity of woodchip biochar, a widely available waste material, for phosphate (PO43−), nitrate (NO3−), and ammonium (NH4+) in raw and secondary-treated wastewater, and compared the results against those obtained using synthetic solutions. Approach to equilibrium was reached quicker for NH4+ (≈20 min) than for NO3− and PO43− (≈40 min), with NH4+ removal reaching up to 80% at a dosage of 20 g/L. Nutrient adsorption kinetics were best described by the pseudo-second-order model for the anionic species (NO3− and PO43−), while the pseudo-first-order model provided a better fit for the cationic species NH4+. The Freundlich isotherm provided a good fit to the equilibrium data for all species, indicating the presence of heterogeneous adsorption sites. SEM–EDX and FTIR analyses confirmed nutrient adsorption onto the biochar surface and highlighted the involvement of carboxyl and hydroxyl functional groups, with FTIR showing the greatest spectral changes for NH4+. Adsorption tests using secondary-treated wastewater showed high removal efficiencies (100% PO43−, 25.4% NO3−, 89.5% NH4+), whereas performance in raw wastewater was poor (maximum 32% NH4+). Overall, woodchip biochar demonstrates strong potential as a tertiary treatment material, and its nutrient-saturated form may be reused as fertiliser, supporting nutrient recovery within a circular-economy framework. |
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| Keywords: |
woodchips biochar; adsorption; nutrients; wastewater; sustainability; environment |
| College: |
Faculty of Science and Engineering |
| Funders: |
This work is part of Amani Haddouk’s doctoral thesis, funded by the Ministry of Higher Education and Scientific Research, Tunisia |
| Issue: |
2 |
| Start Page: |
211 |