Solid State Phenomena Vol. 262

Abstract: Sulfate is a pollutant present in the mining waste water and acid mine drainage. High levels of sulfate can generate important environmental problems. One of the alternatives proposed for the treatment of water with high levels of sulfate is the use of sulfate-reducing microorganisms. This work describes the synergistic combination of a treatment system for the removal of metals by biosorption with the strain Bacillus sp. NRRL-B-30881 to reduce the inhibiting concentration of metals in waters, followed by a new process of sulfate removal that uses a halotolerant sulfate-reducing microbial consortium. The results show that the sulfate reducing consortium can be cultured and is able to reduce the sulfate concentration using cheaper complex organic substrates like spirulina, cellulose and industrial starch. The sulfate reducing consortium was cultured on a bioreactor with Celite R-635, as support material. Using this bioreactor it was possible to reduce the sulfate concentration in the culture medium in batch or semi-continuous operation. An acid mine drainage was pretreated by lime and treated by biosortion in order to increase the pH and reduce the heavy metals concentration. Subsequently the remaining sulfate was removed by the developed process. This integrated biological process represents a more economical alternative for the removal of metal by biosortion and the removal of sulfate using a sulfate reducing consortium.

Abstract: Bacteria which are adapted both to high content of toxic compounds and to the environments grow in autochthonous communities of gold heap leach (HL) wastes. In the following study of HL waste from a deposit in the Sakha (Yakutia) Republic (Russia) it was shown that microbial processes had a greater impact on the degradation of cyanides and of complex copper and nickel cyanides, respectively, compared to a chemical degradation. The diversity of bacterial communities growing under natural and model conditions was determined.

Abstract: Phage surface display technology is a useful tool for the identification of biosorptive peptides. In this work it is used for the identification of cobalt, nickel and gallium binding peptides. We present methods for the enrichment of metal ion binding bacteriophage clones from a commercial phage display library. Metal ion selective peptides are suitable to separate as well as concentrate cobalt and nickel from copper black shale leaching products (EcoMetals project) and gallium from industrial waste waters (EcoGaIn project). In contrast to common capture methods of specific binding phage for solid materials the ionic species have to be immobilized prior to the bio-panning procedure. This was realized by chemical complexation of the metal ions using commercial complexing agents on porous matrices. Moreover, an option to harvest non elutable strong binding phage is proposed.

Abstract: Due to the advancing development of new technologies and consumer goods the future demand for raw materials will rise significantly. The finite primary raw materials will not be able to meet the demand quickly enough or the prices for the extraction will rise enormously. In consequence, a recycling of process waste and end of life products will be in future an essential step in order to meet the demand. Y₂O₃:Eu fluorescent phosphor was identified as the main composition in phosphor waste fractions and was chemical leached and bioleached with A. ferrooxidans. A selective leaching towards Y in bioleaching batches was observed and already after four days 100 % could be leached. The bioleaching with the bacteria showed no significant differences in comparison to the abiotic control without microorganism. Initial Fe³⁺ in the medium was identified as the driving force and lower extraction efficiencies of the biotic batches were attributed to a biosorption process and to high pH-values. This work showed that the extraction of yttrium out of waste products with high Y₂O₃:Eu content by chemical leaching with Fe-addition under mild conditions offers a good perspective to support the material demand of Y in the future growing market. In comparison to bioleaching of other fluorescent phosphors and waste fractions leaching efficiencies up to 100% were achieved and it was identified that the microorganisms can positively influence the leaching effect. Furthermore, it became obvious that the leaching behavior of microorganisms was highly dependent on the sample material. As relevant parameters mainly the structural composition of the phosphor was identified.

Abstract: During the processing of refractory gold ores, cyanide (CN^-) and residual sulphur species react to form an effluent stream containing thiocyanate (SCN^-) and residual CN^-. The release of SCN^- and CN^- containing effluent water to the environment is prohibited, necessitating effective treatment prior to discharge and/or reuse of contaminated plant water. Biologically mediated effluent remediation processes have been developed for commercial use, to remediate SCN^- containing effluents, with the aim of enabling recycling of process water and improving the quality of effluent water prior to disposal. Bioremediation processes to treat these effluents rely on a complex consortium of microorganisms to metabolise the SCN^- resulting in the production of ammonium that is in turn removed by conversion to nitrite and subsequent denitrification. Increasingly, genomic methods are being used to investigate processes in wastewater treatment to identify key microbial species and, thereby, inform the rationale design and operation of these bioremediation systems. The microbial ecology of laboratory-based SCN^- degrading bioprocesses have been investigated, using genome resolved metagenomics, to provide detailed information on the community composition and metabolic profile of abundant microbial community members. Our on-going research is focused on developing a greater understanding of the heterotrophic and autotrophic populations of microorganisms within the SCN^- degrading community as well as the role of the component members in SCN^- destruction. We are interested in the formation of microbial biofilm and the spatial distribution of key microorganisms within the resulting biofilm communities. This information is being used to inform further rational development of SCN^- degradation processes for treatment of contaminated wastewater effluents.

Abstract: In the recent decades phytoremediation became an emerging technology for the stabilization and rehabilitation of slightly to medium heavy metal contaminated sites, as well of mining sites. In previous own studies the general suitability of Helianthus tuberosus under slightly acidic soil pH and increased heavy metal (HM) concentrations was successfully tested. Phytoremediation was here investigated as a suitable remediation method for the stabilization of a U mining site near Ronneburg in Thuringia/ Germany. In the experiments presented here, the uptake of heavy metals/ radionuclides (HM/R) of H. tuberosus from test field substrate with different soil additives and mineral fertilizers under variation of soil pH was tested in pot and real field experiments. Compost was added in different masses (40 – 120 t/ha), and CaO was added in several experiments. The test field soil without additives (pH 4.65) was applied as control experiment. Good growth yields for tubers and shoot biomass were achieved for the addition of compost and CaO, but also for N-fertilization. The highest metal concentrations were achieved at the test field site for Al with 2.1 g/kg in roots at an N-fertilized soil of pH 4.6, furthermore 2.4 g/kg Fe, 0.66 g/kg Mn, 0.9 mg/kg U, and 1.9 g/kg Mn in shoots (transfer factor 2.8). Good metal transfer factors were also achieved for Zn, Cd and Co. As a conclusion from these results, H. tuberosus is suited as a plant for phytostabilization and phytoextraction at such a site and for the subsequent winning of bioenergy. It was growing successful under the rough soil and climatic conditions at this test field site.

Abstract: In Mexico and in the world, the metallurgical, petroleum and chemical industries, among others, generate large amounts of pollutants, which when deposited in dams or discharged into rivers, ponds or directly into aquifers generate serious problems for the environment. Biosorption is the phenomenon of passive uptake of metal ions with non-living organic materials, known as biomass, which are generally industrial waste. Active uptake with live biomass is called bioaccumulation. Biosorption is based on the property of some types of inactive or dead biomass to uptake and accumulate these elements by different mechanisms. There are several mechanisms that explain the fixation and retention of metals by the biosorbent used: physical adsorption, ion exchange, complexation, chelation etc. In this work the behavior of three organic residues from the tequila production process at Tarimoro plant, the fiber or bagasse obtained from the must from tequila processing, agave leaves and solid tequila vinasse were evaluated. The tests were carried out by contacting the biomass with a solution containing metal cations such as Cu, Fe and Mn. The maximum adsorption capacity was obtained at a pH of 8 (98% copper adsorption) with agave fiber biomass at temperature of 25°C. The samples studied at temperatures of 25°C showed the lowest concentration values ​​of Cu²⁺ in residual solution. The adsorption process was found dependent on pH and time. The results obtained allow to affirm that organic wastes from the elaboration of tequila are a viable alternative as biomass in the bioremediation process of toxic heavy metals by a biosorption technique.

Abstract: The large cost of the flotation reagents used in the first-of a two-stage desulphurization flotation process, developed for the treatment of South African waste coal ultrafine tailings, has motivated the investigation of Mycobacterium phlei as an alternative coal bioflotation reagent. Attachment experiments were used to confirm that the microbe attaches to South African coal selectively over pyrite or gangue material present in the coal. Subsequent small scale batch floats using M. phlei successfully showed that the bioflotation process can upgrade and desulphurize the coal tailings feed, and delivered approximately the same concentrate yields as the optimised chemical flotation conditions (37 – 39%). However, a projected financial feasibility analysis that assessed the incorporation of the M. phlei into the two-stage flotation process found that the bioflotation process was not profitable due to the very large flow rate of cells required (2×10¹⁶ cells/ton coal) and the associated additional equipment and growth media component costs.

Abstract: It has been a major issue for urgent solution in China as a result of a series of poisoning cases caused by cadmium. Yet there is no effective methods for removal of cadmium from the paddy soils. Microbial leaching process as an effective approach is currently applied to remediate the contaminated soils. In this study, bioleaching of cadmium from contaminated paddy soils by consortium of autotrophic and indigenous cadmium-tolerant bacteria was applied. The bioleaching results showed that the leaching rate of cadmium was from 74.93% to 92.76%. The distribution of the Cd fractions had a significant change before and after bioleaching with the organic fraction and residues fraction mainly remained. Moreover, the microbial community analysis showed that the Acidithiobacillus and Acidiphilium became the dominant genus in the bioleaching process. The combination of bioleaching with acidophilic chemolithotrophic microorganisms and the cadmium-resistant bacteria provides a potential process for bioremediation of metal-contaminated soils.

Abstract: Bioremediation is the process of detoxification or elimination of pollutants using microorganisms with different metabolic capabilities. Biodegradation by natural populations of microorganisms is one of the primary mechanisms by which oil and other pollutants of hydrocarbon origin can be removed from the environment and it is also much cheaper than the other remediation technologies.In this study, we analyzed the samples of historical waste from the oil industry, which contained sand, organic materials, heavy fuel oil and catalysts used during the process of hydrodesulfurization (HDS) of oil. The aim was to examine the fate of cobalt and molybdenum, toxic heavy metals present in those catalysts. A consortium of microorganisms isolated from the complex pollutants from the oil industry was added to the samples. During the study, beside the transformation of cobalt and molybdenum forms, we also monitored the biodegradation process of the total petroleum hydrocarbons (TPH).