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Generation of Acid Mine Drainage
Published in Bruno Bussière, Marie Guittonny, Hard Rock Mine Reclamation, 2020
Benoît Plante, Gary Schudel, Mostafa Benzaazoua
This Fe release will also be increased when highly oxidized wastes are placed in more reduced conditions—for example, if an oxygen barrier–type cover is installed over tailings (e.g., see Chapters 6, 7, and 8). As a result, covering weathered AMD-generating tailings in a manner that prevents oxygen ingress will not instantly improve the water quality. Instead, a gradual improvement is to be expected, as a new equilibrium is established within the more reduced, induced conditions (e.g., Bussière et al. 2009; Ethier 2018; Ethier et al. 2018; Pabst et al. 2017, 2018). An increase in acid generation and metals release can even be anticipated within the first months or years after reclamation, which will gradually decrease upon depletion of the accumulated secondary iron oxyhydroxides (e.g., Ribeta et al. 1995; Ethier et al. 2018). In the meantime, it can be appropriate to install a passive treatment system in order to meet the water quality criteria (see Chapter 11 for a review of passive treatment methods).
Leaching, bioleaching, and acid mine drainage case study
Published in Katalin Gruiz, Tamás Meggyes, Éva Fenyvesi, Engineering Tools for Environmental Risk Management – 4, 2019
H.M. Siebert, G. Florian, W. Sand, E. Vaszita, K. Gruiz, M. Csővári, G. Földing, Zs. Berta, J.T. Árgyelán
The design of passive systems must accommodate slow reaction rates; thus, passive treatment systems are best suited to AMD with low acidity (<800 mg CaCO3/L), low flow rates (<50 L/sec), and therefore low acidity loads (<100–150 kg CaCO3/day) (Taylor et al., 2005). The life expectancy of a passive treatment system depends on the mass of limestone and/or organic matter in the system. The available porosity within the limestone and organic matter can also affect life expectancy, as porosity determines the capacity to store treatment precipitates. Passive treatment system may become ineffective if the system gets blocked with treatment precipitates due to insufficient porosity within the limestone/organic matter layers (Ziemkiewicz et al., 1994; Hedin et al., 1994a,b).
Role of multiple substrates (spent mushroom compost, ochre, steel slag, and limestone) in passive remediation of metal-containing acid mine drainage
Published in Environmental Technology, 2019
Verma Loretta M. Molahid, Faradiella Mohd Kusin, Zafira Madzin
In order to prevent problems arising from AMD formation, the AMD needs to be treated before being discharged into the stream. Previous researches have been mostly associated with the mitigation techniques or technologies for AMD. For instance, Chowdhury et al. [1] focused on AMD treatments that include the prevention and remediation technologies. The prevention techniques focused on controlling the source of AMD whereas the remediation techniques focused on treating AMD that is already produced before it can be released into the water bodies. Remediation techniques consist of two broad categories, namely active and passive treatments. Although active treatment systems are effective and reliable, their high installation cost, power, and intensive labour requirements for maintenance make them the second choice for treating AMD [1,3]. Passive treatment system on the other hand is based on naturally occurring chemical and biological processes, which does not require continuous chemical input. Examples of passive treatment technologies for AMD are aerobic and anaerobic wetlands, sulphate-reducing bioreactors, successive alkalinity producing system (SAPS), slag leach beds (SLB), and limestone leach beds (LSB) [3]. Goetz and Riefler [4] stated that the use of steel slag leach beds for AMD treatment is effective, but it should have enhanced performance if some factors are considered. Whereas Patil et al. [5] described the effectiveness of limestone as a filter media for manganese (MnII) removal. Muhammad et al. [6] found that spent mushroom compost (SMC) has high removal efficiency for removing heavy metals, and has the potential of removing sulphate. The SMC greatly assisted the overall treatment when mixed with other treatment media. In addition, Sapsford et al. [7] demonstrated that the ochre from both active and passive treatments of coal mine drainage can be transformed into an effective water treatment reagent by simple acid dissolution for the removal of dissolved phosphorous from municipal wastewater and zinc from non-coal mine waters.