A novel approach to mine water treatment

Williams, Keith Philip; Dey, Matt; Sadler, P. J. K.

doi:10.2462/09670513.822

Cited by 5 publications

(5 citation statements)

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“…Unfortunately, quantitative target criteria recommendations, especially for pre-treatment, are limited to rather rough approximations, for instance aiming at 50-70% iron removal in upstream settling ponds (Dey et al 2003;Parker 2003). A 50% reduction of a highly ferruginous inflow may, however, still result in wetland overloading, especially if the wetland receives high concentrations of ferrous iron.…”

Section: Discussionmentioning

confidence: 99%

The Role of Macrophytes in Constructed Surface-flow Wetlands for Mine Water Treatment: A Review

Opitz

Alte²,

Bauer³

et al. 2021

Mine Water Environ

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Constructed wetlands are a standard sustainable technology in waste and mine water treatment. Whereas macrophytes actively contribute to decomposition and/or removal of wastewater’s organic pollutants, removal of hydrolysable metals from mine water is not attributable to direct metabolic, but rather various indirect macrophyte-related mechanisms. These mechanisms result in higher treatment efficiency of (vegetated) wetlands relative to (unvegetated) settling ponds. Contribution of macrophytes to treatment predominantly includes: enhanced biogeochemical oxidation and precipitation of hydrolysable metals due to catalytic reactions and bacterial activity, particularly on immersed macrophyte surfaces; physical filtration of suspended hydrous ferric oxides by dense wetland vegetation down to colloids that are unlikely to gravitationally settle efficiently; scavenging and heteroaggregation of dissolved and colloidal iron, respectively, by plant-derived natural organic matter; and improved hydrodynamics and hydraulic efficiency, considerably augmenting retention and exposure time. The review shows that constructed surface-flow wetlands have considerable advantages that are often underestimated. In addition to treatment enhancement, there are socio-environmental benefits such as aesthetic appearance, biotope/habitat value, and landscape diversity that need to be considered. However, there is currently no quantitative, transferrable approach to adequately describe the effect and magnitude of macrophyte-related benefits on mine water amelioration, let alone clearly assign optimal operational deployment of either settling ponds or wetlands. A better (quantitative) understanding of underlying processes and kinetics is needed to optimise assembly and sizing of settling ponds and wetlands in composite passive mine water treatment systems.

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Section: Discussionmentioning

confidence: 99%

The Role of Macrophytes in Constructed Surface-flow Wetlands for Mine Water Treatment: A Review

Opitz

Alte²,

Bauer³

et al. 2021

Mine Water Environ

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“…This led to the idea that perhaps this accidental but very effective iron removal could be engineered into a system specifically designed to achieve it. Subsequent trials at laboratory and small field scale indicated promising results (Dey et al 2003;Sapsford et al 2005). As a result of this initial promise a large pilot scale system was constructed at the former Taff Merthyr colliery site in South Wales where net-alkaline mine water is being treated in a conventional lagoon/wetland system.…”

Section: Introductionmentioning

confidence: 94%

Low Footprint Passive Mine Water Treatment: Field Demonstration and Application

Sapsford

Barnes

Dey³

et al. 2007

Mine Water Environ

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This paper presents iron and manganese removal data from a novel low footprint mine water treatment system. The paper discusses possible design configurations, and demonstrates that the system could treat 1 l/s of mine water containing 7.2 mg/l of Fe to \1 mg/l with a system footprint of 66 m 2 . A conventional lagoon and aerobic wetland system based on standard sizing criteria would require a minimum of 135 m 2 to achieve the same treatment. Other advantages of the system are that it polishes manganese concentrations, produces ochre that is dense (15% w/v) and free of plant detritus (and therefore amenable to recycling) and that heavy machinery will generally not be required for construction of similar scale systems.

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“…The gravity fed VFR system was adapted from the original design used in an initial field trial at the Taff Merthyr site in South Wales,[ 23 , 34 ] using an adapted 1 m³ intermediate bulk container. A length of coiled, slotted drainage pipe was placed in the bottom of the tank.…”

Section: Methodsmentioning

confidence: 99%

Iron-mineral accretion from acid mine drainage and its application in passive treatment

Florence

Sapsford

Johnson

et al. 2016

Environmental Technology

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This study demonstrates substantial removal of iron (Fe) from acid mine drainage (pH ≈3) in a passive vertical flow reactor (VFR) with an equivalent footprint of 154 m2 per L/s mine water and residence times of >23 h. Average Fe removal rate was 67% with a high of 85% over the 10-month trial. The fraction of Fe passing a 0.22 µm filter (referred to here as Fe-filt) was seen to be removed in the VFR even when Fe(II) was absent, indicating that the contribution of microbial Fe(II) oxidation and precipitation was not the dominant removal mechanism in the VFR. Removal rates of Fe-filt in the VFR were up to 70% in residence times as low as 8 h compared with laboratory experiments where much smaller changes in Fe-filt were observed over 60 h. Centrifugation indicated that 80–90% of the influent Fe had particle sizes <35 nm. Together with analyses and geochemical modelling, this suggests that the Fe-filt fraction exists as either truly aqueous (but oversaturated) Fe(III) or nanoparticulate Fe(III) and that this metastability persists. When the water was contacted with VFR sludge, the Fe-filt fraction was destabilized, leading to an appreciably higher removal of this fraction. Heterogeneous precipitation and/or aggregation of nanoparticulate Fe(III) precipitates are considered predominant removal mechanisms. Microbial analyses of the mine water revealed the abundance of extracellular polymeric substance-generating Fe-oxidizing bacterium ‘Ferrovum myxofaciens’, which may aid the removal of iron and explain the unusual appearance and physical properties of the sludge.

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A novel approach to mine water treatment

Cited by 5 publications

References 0 publications

The Role of Macrophytes in Constructed Surface-flow Wetlands for Mine Water Treatment: A Review

The Role of Macrophytes in Constructed Surface-flow Wetlands for Mine Water Treatment: A Review

Low Footprint Passive Mine Water Treatment: Field Demonstration and Application

Iron-mineral accretion from acid mine drainage and its application in passive treatment

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