Abstract: Aktuelle Entwicklungen auf dem Gebiet der aktiven Wasserbehandlung im Bergbau in den spezifischen Anwendungsgebieten • Behandlung von sauren Bergbauwässern (AMD – acidic mine drainage) mit Schwerpunkt HDS-Technologie (HDS – high-density sludge) • In-situ-Behandlung bergbaubeeinflusster Grundwasserkörper, insbesondere nach Anwendung der In-situ-Laugung (ISL) • In-situ-Behandlung von Tagebaurestseen mit Schwerpunkt In-lake-Verfahren werden hinsichtlich Machbarkeit, technologischer Kenngrößen und Effizienz bewertet und kommen-tiert. Recent developments in the field of active water treatment technologies in the mining sector are re-viewed. Application areas of interest include • Treatment of acidic mine drainage (AMD) emphasizing HDS technology (HDS – high-density sludge) • In-situ treatment of groundwater affected by mining, in particular after the application of in-situ leaching (ISL) • In-situ treatment of lakes arising in former open-pit lignite mines, in particular the application of in-lake methods The various applications are evaluated with regard to feasibility, technical characteristics and treat-ment efficiency.

Abstract: ERWAT's Ancor Wastewater Treatment Works on the Far East Rand commissioned a 10 Ml/day full-scale plant to treat toxic mine-water from the Grootvlei gold mine using primary sewage sludge. The R15-million plant is treating sulphate rich acid mine drainage using the Rhodes BioSURE Process. First, the pumped mine-water is treated at a high-density separation (HDS) plant to remove iron and condition pH levels. Then it is pumped two km via a newly-constructed 10 Ml capacity pipeline to the Ancor works. This mine-water is then mixed together with primary sewage sludge in a mixing tank from where a splitter box directs the material to eight biological sulphate reducing reactors or bioreactors. The overflow water which is rich in sulphide is pumped through the main pump station to another mixing box. Here, iron slurry is mixed with the material before it is again divided between four reactor clarifiers for sulphide removal. The overflow water, now containing reduced sulphate levels and virtually no sulphide is pumped to Ancor's biofilters for removal of remaining Chemical Oxygen Demand (COD) and ammonia following the conventional sewage treatment process for eventual release into the Blesbokspruit.

Abstract: The aim of this study was to operate an upflow anaerobic packed bed reactor (UAPB) containing sulfate reducing bacteria (SRB) under acidic conditions similar to those found in acid mine drainage (AMD). The UAPB was filled with sand and operated under continuous flow at progressively lower pH and was shown to be capable of supporting sulfate reduction at pH values of 6.0, 5.0, 4.5, 4.0 and 3.5 in a synthetic medium containing 53.5 mmol l(-1) lactate. Sulfate reduction rates of 553-1052 mmol m(-3) d(-1) were obtained when the influent solution pH was progressively lowered from pH 6.0 to 4.0, under an optimal flow rate of 2.61 ml min(-1). When the influent pH was further lowered to pH 3.5, sulfate reduction was substantially reduced with only about 1% sulfate removed at a rate of 3.35 mmol m(-3) d(-1) after 20 days of operation. However, viable SRB were recovered from the column, indicating that the SRB population was capable of surviving and metabolizing at low levels even at pH 3.5 conditions for at least 20 days. The changes in conductivity in the SRB column did not always occur with changes in pH and redox potential, suggesting that conductivity measurements may be more sensitive to SRB activity and could be used as an additional tool for monitoring SRB activity. The bioreactor containing SRB was able to reduce sulfate and generate alkalinity even when challenged with influent as low as pH 3.5, indicating that such treatment systems have potential for bioremediating highly acidic, sulfate contaminated waste waters. (c) 2006 Elsevier Ltd. All rights reserved.