A pilot-scale field experiment for the microbial neutralization of a holomictic acidic pit lake

Iron Transformations Induced by an Acid-Tolerant Desulfosporosinus Species

“…Under conditions representative of AMD (i.e., initially low pH, high Fe concentrations), anaerobic microbial activities [i.e., Fe(III) and sulfate reduction] may lead to two major mineralogical (trans)formations: (i) the formation of the ferrimagnetic mineral phase greigite under conditions of high Fe(II):Fe(III) ratios and (ii) the transformation of schwertmannite to goethite. A goal of anaerobic AMD treatment systems (e.g., anoxic limestone drains) is to minimize Fe(III) formation, while precipitating Fe(II) and other metals as sulfide phases (4,8,27,22). In these Fe(III)-free systems, greigite may be an important product of SRB activities.…”

“…While anaerobic microbial activities (notably sulfate reduction) have been exploited for AMD remediation (4,8,22,27), in the context of iron mound systems, they may be considered detrimental to the overall goal of oxidatively precipitating Fe and maintaining the Fe(III) (hydr)oxide precipitates. The most abundant anaerobic terminal electron acceptors in AMD-impacted systems are sulfate and the Fe(III) (hydr)oxides.…”

“…SRB activities may also lead to the concentration of iron sulfide species at the terrestrial surface, in closer proximity to atmospheric O 2 , and pose a greater risk of acid production should O 2 infiltrate the sediments (22,28). Anaerobic activities associated with AMD-impacted systems remain somewhat nebulous.…”

“…For instance, most cultured acidophilic FeRB reduce Fe(III) optimally in the presence of O 2 (13). SRB activity in AMD-impacted systems is well documented (e.g., 4,14,21,22,27), but given the abundance of sulfate in these systems, surprisingly few acidophilic or acid-tolerant SRB have been recovered in culture (29). Strictly anaerobic SRB that have been isolated from AMD-impacted systems fall into the genus Desulfosporosinus (1,29,33,60), and representatives of this genus are frequently detected in anoxic regions of AMD-impacted systems (7,23,32,55,68).…”

Sourcing Organic Materials for Pit Lake Bioremediation in Remote Mining Regions

“…There are few field scale studies of pit lake rehabilitation with AMD remediation (Lessmann et al 2003;Geller et al 2009;Ronicke et al 2010). Schultze et al (2009) lists remediation options for German pit lakes, in order of effectiveness and reliability, as: rapid filling (where available), chemical treatment, and biological treatment.…”