Novel approaches to passive and semi-passive treatment of zinc-bearing circumneutral mine waters in England and Wales

Kennedy, Julia ORCID: https://orcid.org/0000-0003-4482-6392, Okeme, Ilemona and Sapsford, Devin ORCID: https://orcid.org/0000-0002-6763-7909 2023. Novel approaches to passive and semi-passive treatment of zinc-bearing circumneutral mine waters in England and Wales. Fosso-Kankeu, Elvis and Mamba, Behkie B, eds. Hybridized Technologies for the Treatment of Mining Effluents, Scrivener Publishing LLC, pp. 147-175. (10.1002/9781119896920.ch6)

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Abstract

Circumneutral mine waters where the principal contaminants are Zn with lesser concentrations of other contaminants (such as Fe, Mn, As, Cd, Pb, Cu) are common across England and Wales, arising from legacy Zn/Pb/Cu/Sn mines. These affect 262 water bodies and lead to failures to meet European Union Water Framework Directive standards failures. In Wales, there are 1,300 legacy mines affecting over 700 km of rivers. Typical zinc concentrations in discharging mine water range from low mg L −1 to tens of mg L −1 , while these discharges are not as aggressive as acid mine drainage, they nevertheless cause substantial environmental harm. Typical passive treatment approaches to this type of mine water rely on sulphate reducing bioreactors and the removal of metals as sulphides. While these can be successful, a broad range of alternative treatment options needs to be developed and appraised. This chapter summarizes the chemistry of circum-neutral zinc rich discharges and highlights some of the constraints on standard approaches to treatment. The chapter then examines two novel approaches. These are (i) A semi-passive/active approach based on dosing sodium carbonate (pH 8.5–9), followed by passive settlement/filtration and (ii) aerobic Vertical Flow Reactors where coprecipitation/sorption of Zn, As, Cu and Pb with iron and manganese oxides can be utilised to polish low concentrations of contaminants. Outline assessment of reagent costs and sustainability analyses indicate that these promising approaches are worthy of further investigation.

Item Type:	Book Section
Date Type:	Publication
Status:	Published
Schools:	Engineering
Publisher:	Scrivener Publishing LLC
ISBN:	978-1-119-89642-5
Last Modified:	05 Sep 2023 08:41
URI:	https://orca.cardiff.ac.uk/id/eprint/162081

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