Low Footprint Passive Mine Water Treatment: Field Demonstration and Application

Abstract

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.

International Trials of Vertical Flow Reactors for Coal Mine Water Treatment

“…The VFR trials removed Mn surprisingly well at circumneutral pH with average removal efficiencies of 97% at the NZ1 trial, and average removal efficiencies of 69.5% at the SK trial, which often achieved 100% removal, consistent with those obtained in the UK1 trial (Sapsford et al 2007). Given that abiotic oxidation rates for Mn(II) are low below pH 9, Mn removal mechanisms within NZ1 and SK were Table 3 Average total acidity and alkalinity, SO expected to be similar to those observed in UK1, where Mn removal took place within the bed rather than in the water column, potentially through bacterial oxidation and/or heterogeneous catalysis of Mn(II) oxidation on HFO and Mn oxide surfaces (Geroni 2011).…”

“…XRD and ICP-OES analyses (Table 5) indicated that the sludge layer consisted of an amorphous Fe precipitate with trace concentrations of Mn and Ca as the main second and third element concentrations, in similar proportions to UK1 sludge samples (Sapsford et al 2007). …”

“…The MW passed through the bed into the underdrain, under a baffle wall, and up through a rise chamber where it exited the system. A detailed description of the system, schematics, photographs, and water and sludge sampling and analysis are available in previous publications (Sapsford et al 2007;Barnes 2008;Sapsford and Williams 2009).…”

“…The SK trial followed the design used by Sapsford et al (2007) and received water collected directly from the shaft of an abandoned underground coal mine. The trial consisted of a 1.5 m 2 footprint container as a VFR treatment tank with a bed of 10 mm coarse gravel 100 mm thick, overlain by a sand layer 100 mm thick.…”

“…In circumneutral net-alkaline water, iron removal occurred by self-filtration through the ochre bed and heterogeneous iron oxidation and precipitation of hydrated ferric oxides and oxyhydroxides within the ochre bed (Sapsford and Williams 2009;Sapsford et al 2007). Under acidic conditions, iron removal occurred predominantly by heterogeneous precipitation and/or aggregation of nano-particulate Fe(III) precipitates (Florence et al 2016).…”