Biological sulfate reduction is increasingly replacing chemical unit processes in mining biotechnology. Sulfate reducing bacteria (SRB) can be used for treating ground- and surface waters contaminated with acid mine drainage (AMD), and for recovering metals from wastewater and process streams. Biologically produced H2S precipitates metals as metal sulfides, while biogenic bicarbonate alkalinity neutralizes acidic waters. This paper reviews various passive and active SRB-based alternatives as well as some process design aspects, such as reactor types, process configurations, and choices of substrates for sulfate reduction. The latest developments of using various low-cost substrates together with new bioprocess designs are increasing the uses and applications of SRB-based bioreactors in AMD control and selective metal recovery.

Sulfate Reduction Based Bioprocesses for the Treatment of Acid Mine Drainage and the Recovery of Metals

A review is presented of 28 studies in the literature of diatoms in environments at pH ≤35, including natural and anthropogenic acid sources A total of 124 diatom taxa have been reported, but many are likely to have been accidental occurrences, because only a few specimens were found Approximately 19 taxa abundant in at least one study or common in several studies are considered true inhabitants of highly acidic waters These include: Achnanthes minutissima, Eunotia exigua, E tenella, E septentrionalis, E osoresanensis, E arcus, E glacialis, E pectinalis, Frustulia rhomboides, F rhomboides var saxonica, Nitzschia capitellata/subcapitellata, Nitzschia communis, Nitzschia pusilla, Nitzschia vasta, Pinnularia acoricola, P obscura, P braunii var amphicephala, P subcapitata and P terminitina There are inconsistencies in the taxonomy of several of these species and possible synonymies could lower the number of taxa to less than 9 Compared to diatom species richness in environments at pH 45–50, there are many fewer taxa in environments ≤ pH 35, suggesting a threshold between pH 45 and 35 below which many species are unable to maintain a population

A review of diatoms found in highly acidic environments

Acidification of lead/zinc mine tailings and its effect on heavy metal mobility

Barriers to implementing cleaner technologies and cleaner production (CP) practices in the mining industry: A case study of the Americas

Contamination of aquatic environments as a consequence of deep metal mining for Pb, Zn, Cu, Cd, and Fe is of widespread international concern. Pollution resulting from metal mining activities can result in significant environmental and ecological degradation and can pose serious risks to human health through contamination of food and drinking water. This paper provides a review of the impacts of deep metal mine water discharges on riverine sedimentology, hydrology, and ecology and explores strategies for the restoration of rivers draining historically abandoned metal mines. The review is concluded by identifying key recommendations for future research. An interdisciplinary approach, incorporating collaborative expertise and knowledge regarding sedimentological, hydrological, chemical, and ecological consequences of active and historic deep metal mining, is advocated and should be utilized for effective river basin management and the remediation and restoration of mining-impacted river systems.

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The Impairment of River Systems by Metal Mine Contamination: A Review Including Remediation Options

The drainage of waters from abandoned coal and metal mines is often acidic with an elevated heavy metal content. Interaction between this acid mine drainage and the environment can cause gross pollution. Whilst temporary engineered remediation can lessen the impact, complete amelioration is only possible using active and/or passive treatment systems. Active technologies are costly as they often include the controlled addition of chemicals which can produce a contaminated effluent that requires additional treatment. The study of natural marshland within mining areas has led to the development of using constructed wetlands as a potential treatment option. The chemistry of acid mine drainage often requires the use of aerobic (mine water oxidation) and anaerobic (sulphate reduction) systems and commonly utilizes some form of pretreatment system. The science of wetland treatment processes is still not fully understood and as a consequence the full potential of the technology has yet to be realized. There is evidence, however, that the use of passive treatment is a realistic and cost-effective remedial method for acid mine drainage.

James D.F. Robinson

Papers

Acid Drainage from Mines