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Lookup NU author(s): Dr Catherine GandyORCiD, Dr Beate Christgen, Professor Adam Jarvis
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2025 by the authors.Deployment of nature-based systems for mine water treatment is constrained by system size, and the evidence suggests decreasing hydraulic conductivity (Ksat) of organic substrates over time compromises performance. In lab-scale continuous-flow reactors, we investigated (1) the geochemical and hydraulic performance of organic substrates used in nature-based systems for metals removal (via bacterial sulfate reduction) from mine water, and then (2) the potential to operate systems modestly contaminated with Zn (0.5 mg/L) at reduced hydraulic residence times (HRTs). Bioreactors containing limestone, straw, and wood chips, with and without compost and/or sewage sludge all achieved 88%–90% Zn removal, but those without compost/sludge had higher Ksat (929–1546 m/d). Using a high Ksat substrate, decreasing the HRT from 15 to 9 h had no impact on Zn removal (92.5% to 97.5%). Although the sulfate reduction rate decreased at a shorter HRT, microbial analysis showed high relative abundance (2%–7%) of sulfate reducing bacteria, and geochemical modelling pointed to ZnS(s) precipitation as the main attenuation mechanism (mean ZnS saturation index = 3.91–4.23). High permeability organic substrate treatment systems operated at a short HRT may offer potential for wider deployment of such systems, but pilot-scale testing under ambient environmental conditions is advisable.
Author(s): Gandy CJ, Christgen B, Jarvis AP
Publication type: Article
Publication status: Published
Journal: Minerals
Year: 2025
Volume: 15
Issue: 7
Online publication date: 21/07/2025
Acceptance date: 18/07/2025
Date deposited: 04/08/2025
ISSN (electronic): 2075-163X
Publisher: Multidisciplinary Digital Publishing Institute (MDPI)
URL: https://doi.org/10.3390/min15070765
DOI: 10.3390/min15070765
Data Access Statement: The data presented in this study are available upon request from the corresponding author, subject to the prior permission of the research funder being granted.
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