Use of Emulsified Edible-Oil for In-Situ Bioremediation of Acid Mine Drainage
M. Tony Lieberman, Solutions Industrial & Environmental Services, Inc., Raleigh, NC

Sulfate-reducing Bacteria as Contaminants of Industrial Systems – Effects of pH on Sulfidogenic Activity
Kjeld Ingvorsen, University of Aarhus, Aarhus, Denmark

Metal Immobilization by In Situ Bioprecipitation: Comments about Carbon Source Use, Process Efficiency and Sustainability
Ludo Diels, Flemish Institute for Technological Research (VITO), Mol, Belgium

Algal Bioremediation of the Berkeley Pit Lake System: An In Situ Test Using Limnocorrals 
Grant Mitman, Montana Tech of The University of Montana, Butte, MT

Biotechnological Applications of Methane as Electron Donor for Biological Sulfate Reduction
Roel Meulepas, University Wageningen, The Netherlands

Recent US EPA Field-Scale Bioreactors for Mine Drainage
Edward R. Bates, US EPA, Cincinnati, OH

Prevention of Acid Drainage Generation from a Dump Consisting of Mining Wastes

Stoyan N. Groudev, University of Mining and Geology, Studentski grad, Sofia 1700, Bulgaria, Tel/Fax: +359-2-687396, e-mail: groudev@mgu.bg
Marina V. Nicolova, University of Mining and Geology, Studentski grad, Sofia 1700, Bulgaria, Tel/Fax: +359-2-687396, e-mail: mnikolova@mgu.bg
Irena I. Spasova, University of Mining and Geology, Studentski grad, Sofia 1700, Bulgaria, Tel/Fax: +359-2-687396, e-mail: spasova@mgu.bg
Plamen S. Georgiev, University of Mining and Geology, Studentski grad, Sofia 1700, Bulgaria, Tel/Fax: +359-2-687396, e-mail: ps_georgiev@mgu.bg

In the uranium deposit Curilo, Western Bulgaria, a dump consisting of about 800 tons of rich-in-pyrite mining wastes was, after rainfall, a large source of acid drainage waters. These waters had a pH in the range of about 2.3 – 3.5 and contained radionuclides (uranium, radium), heavy metals (copper, zinc, cadmium, lead, nickel, cobalt, iron, manganese), arsenic and sulphates in concentrations usually much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The generation of these pollutants was connected with the oxidative activity of the indigenous acidophilic chemolithotrophic bacteria inhabiting the dump. This activity was ceased by adding a multicomponent mixture to the top layer of the dump and on its surface. This mixture consisted of crushed limestone, different biodegradable solid organic substrates (cow manure, plant compost, hay) and soil. The rich-in-organics cover was maintained saturated with water and was inhabited by a mixed microbial community consisting mainly of heterotrophs. This community created a system characterized by a neutral pH and absence of molecular oxygen, i.e. conditions not favorable for the acidophilic chemolithotrophs. As a result of this, during an experimental period of more than 5 years, the dump effluents after rainfall had a pH around the neutral point and contained no pollutants in concentrations higher than the relevant permissible levels.

Sulfate-reducing Bacteria as Contaminants of Industrial Systems – Effects of pH on Sulfidogenic Activity

Kjeld Ingvorsen, PhD, PhD, Department Head, University of Aarhus, Institute of Biological Sciences, Department of Microbiology, Building 540, Ny Munkegade, DK-8000 Aarhus C, Denmark, Tel: +45 8942 3245, Fax: +45 8942 2722, Email: Kjeld.Ingvorsen@biology.au.dk
Kasper U. Kjeldsen (PhD), Marie B. Nielsen (MS) and Lone Abildgaard (MS), University of Aarhus, Institute of Biological Sciences, Department of Microbiology, Building 540, Ny Munkegade, DK-8000 Aarhus C, Denmark.

Sulfate-reducing bacteria (SRB) are ubiquitous in anaerobic environments such as soils, sediments, wastewaters and gastrointestinal systems.  Due to the high oxygen tolerance of some SRB they are also commonly found in temporary oxic habitats such as biofilms, algal mats, activated sludge and a large variety of industrial systems.  SRB play a major role in the turnover of organic matter in many ecosystems and further may effect immobilization of toxic heavy metals from AMD water, souring of oil and gas bearing formations and cause corrosion of iron and steel constructions.

In order to either inhibit or exploit the metabolic activity of SRB it is important to know the physico-chemical limits for survival and growth of these bacteria.  The present talk will discuss the effects of pH on the activity of extant SRB and present data from a study of the microbial population within the piping system of a Danish district heating plant. During this study several novel types of alkaliphilic suldidogenic anaerobes were isolated and characterized.  These strains may be involved in metal corrosion occasionally observed in the piping systems of district heating plants.  A novel alkaliphilic sulfate-reducing bacterium was isolated from biofilm on a mild steel surface. This bacterium (strain RT2) grew at pH values up to approx. 10 at 40°C.  Our results also indicate that anaerobic bacteria capable of reducing elemental sulfur, sulfite and thiosulfate could be as important as the SRB in producing hydrogen sulfide in the piping system of the plant.

Metal Immobilization by In Situ Bioprecipitation: Comments about Carbon Source Use, Process Efficiency and Sustainability

L. Diels, J. Geets, W. Dejonghe, S. van Roy, and K. Vanbroekhoven, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium, Tel: 0032-14-33-6924, Fax: 0032-14-58-0523

About 45% of the contaminated sites are dealing with heavy metal problems. Metals are spread in the environment by mining activities, surface treatment and non ferrous processing. As heavy metals can not be degraded, removal or immobilization (leading to bioavailability reduction) are the only risk reducing measures that exist. Next to the often used but expensive pump an treat technologies, heavy metals can be immobilized by inducing sulfate reducing bacteria to transform the sulfates, that are very often present in the same groundwater (due to the metal mining or processing activities), into sulfides. These sulfides will precipitate the metals as insoluble metal sulfides. At the moment several studies have demonstrated the feasibility of this In Situ Bioprecipitation Process (ISBP) as well at lab scale (batch and column tests) as at field scale. However some questions arise concerning the continuation of the process, the efficiency and the sustainability of the precipitates. The presented study will try to answer these questions. The study is based on more than 10 different studies, all done by the same authors, on different groundwaters and aquifer samples.  

Biotechnological Applications of Methane as Electron Donor for Biological Sulfate Reduction

Ir. Roel J.W. Meulepas, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands, Tel: +31 317 485264, Fax: + 31 317 4 82108, Email: Roel.Meulepas@wur.nl
Ilje Pikaar, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands, Tel: +31 317 483339, Fax: + 31 317 4 82108, Email: Ilje.Pikaar@wur.nl
Jarno Gieteling, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands, Tel: +31 317 485593, Fax: + 31 317 4 82108, Email: Ilje.Pikaar@wur.nl
Ir. Christian Jagersma, Hesselink van Suchtelenweg 4, 6703 CT Wageningen, The Netherlands, Tel: +31 317 483739, Fax: +31 317 483829, Email: Christian.Jagersma@WUR.nl
Prof. Dr. Ir. Alfons J.M. Stams Hesselink van Suchtelenweg 4, 6703 CT Wageningen, The Netherlands, Tel: +31 317 483101, Fax: +31 317 483829, Email: Fons.Stams@WUR.nl
Dr. Ir. Piet N.L. Lens, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands, Tel: +31 317 483851, Fax: + 31 317 4 82108, Email: Piet.Lens@wur.nl

Biological sulfate reduction is a process used to remove oxidized sulfur compounds and metals from wastewater of the mining and metallurgical industry. Sulfate is biologically reduced to sulfide, which precipitates with metals to form metal sulfides. The metal sulfides are removed from the water by sedimentation and reused in the metallurgical industry as raw material.

For sulfate reduction an electron donor is required. A widely used electron donor, for large-scale applications, is hydrogen. Hydrogen is produced from methane in natural gas or biogas via a process called stream reforming. However, this process requires high temperatures and pressures, resulting in a high-energy loss. Therefore, the emission of the greenhouse gas carbon dioxide and the costs of the wastewater treatment would be greatly reduced if methane could be used directly as electron donor for biological sulfate reduction.  

Biological sulfate reduction with methane as electron donor occurs in deep-sea sediments. Recent research provided evidence for the involvement of a syntrophic consortium of methanogens and sulfate reducers. It is believed that methanogens form hydrogen or acetate via “reversed methanogenesis” and that these compounds serve as electron donors for sulfate reducing bacteria.

Our research examines if methane can be used as electron donor for the reduction of oxidized sulfur compounds (sulfate, sulfite and thiosulfate) in a “high rate” bioreactor. Biomass from anaerobic reactors and deep-sea sediments is screened for sulfide production coupled to methane oxidation, in continuous membrane reactors. In addition, the effect of different co-substrates is investigated. Preliminary results indicate that methane is oxidized to carbon dioxide during sulfide production, when acetate is additionally fed to the reactors.

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