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2 2024

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Improvement of Sorption Capacity and Applicability of Biosorbent by Immobilization

Hroncova Jana, Luptakova Alena, Briancin Jaroslav, Kupka Daniel

Inżynieria Mineralna

2024

Vol. 1, no. 1

645--651

The water contamination by toxic metal ions is a worldwide environmental problem. High concentrations are hazardous for all living organisms, causing many disorders and diseases and ecological damages to the surroundings. Biosorption is an innovative technology that employs inactive and dead biomass (bacteria, fungi, algae, biowaste) for the recovery of metals from aqueous solutions. Sulphate-reducing bacteria utilization is one of the options how to prepare applicable sorbent which removes metal ions from water. This material is created as a consequence of bacteria metabolism in anaerobic environment. The use of freely suspended biomass is often impractical and has some disadvantages. In contrast to this, application of immobilized biomass shows more benefits including increased mechanical strength, resistance to chemical environment, easy separation of cells and effluents, high biomass performance and repeated use in many adsorption/desorption cycles. Cell entrapment is the most widely used method for immobilization. In this technique, the cells are enclosed in a polymeric matrix which is porous enough to allow diffusion of substrate to the cells. The aim of this work was to examine and compare the sorption ability of biogenic iron sulphides created by sulphate-reducing bacteria in “free” and “entrapped” form. Precipitates were synthesized in reagent bottles with bacteria culture and growth media Postgate C, at 30 °C during 60 days, subsequently dried and analysed. Prepared samples were immobilized using sodium alginate. Sorption of cadmium from model solutions was realized in 100 ml Erlenmeyer flasks, with sorbent dose 1 g/l, during 24 hours. During experiments, the samples showed a satisfying stability and maximum adsorption capacity achieved 38 mg/g. The results refer to good sorption properties of immobilized samples and their potential for further practical use.

Bacterial Reduction of Sulfates as Suitable Method for Removal of Sulfates from Acid Mine Drainage

Luptakova Alena, Macingova Eva, Hroncova Jana, Balintova Magdalena, Cikotova Adriana, Luptak Miloslav

Inżynieria Mineralna

2024

Vol. 1, no. 1

569--574

The aim of this work was to investigate of the sulfates removal from acid mine drainage (AMD) by biological method using sulfate-reducing bacteria (SRB). A sample of AMD out-flowing from the Pech shaft of the abandoned and flooded Smolník deposit in Slovak Republic was studied. The untreated AMD (with contents metals) and treated AMD i.e. after of the metals removing by the synthetic sorbent Slovakite were used. The base of the biological sulfates elimination was the sulfates bacterial reduction under influence of SRB genera Desulfovibrio. These bacteria realize the sulfates reduction to hydrogen sulfide at the simultaneously oxidation of energetic substrate. Standard selective nutrient medium DSM-63 and modified selective nutrient medium DSM-63 (without sulfates contents) with standard amount of sodium lactate (as energetic substrate) were used in the experiments with untreated AMD. Standard selective nutrient medium DSM-63 and modified selective nutrient medium DSM-63 with standard, double and triple amount of sodium lactate were used in the experiments with treated AMD. In the case of untreated AMD has been reached low removing of sulfates - 20% efficiency (standard medium) and 26% (modified medium). The formation of heterogeneous precipitates containing metals pointed to the need for treatment of AMD by the initial removal of metals by sorption on Slovakite sorbent and subsequent removal of sulfates by bacterial reduction. The results of experiments with AMD treated in this way showed 49%, 70% and 88% efficiency of sulfate removal when using sodium lactate in standard, double and triple amounts. The results of this work suggest that ratio of substrate quantity and sulfate concentration is one of the key parameter of sulfate reducing condition. However, the price of the energy substrate is also an important factor. Therefore, subsequent experiments will be focused on the use of the more affordable substrates (e.g. whey) or mixed bacterial culture of SRB, which will also be able to use the products of decomposition of basic energetic substrates.