The performance of the brewer’s yeast Saccharomyces cerevisiae to remove metal ions from four batch systems, namely Zn(II), Zn(II)-Sr(II)-Cu(II), Zn(II)-Ni(II)-Cu(II), and Zn(II)-Sr(II)-Cu(II)-Ba(II), and one real effluent was evaluated. Yeast biosorption capacity under different pH, temperature, initial zinc concentration, and contact time was investigated. The optimal pH for removal of metal ions present in the analyzed solution (Zn, Cu, Ni, Sr, and Ba) varied from 3.0 to 6.0. The biosorption process for zinc ions in all systems obeys Langmuir adsorption isotherm, and, in some cases, the Freundlich model was applicable as well. The kinetics of metal ions biosorption was described by pseudo-first-order, pseudo-second-order, and Elovich models. Thermodynamic calculations showed that metal biosorption was a spontaneous process. The two-stage sequential scheme of zinc ions removal from real effluent by the addition of different dosages of new sorbent allowed us to achieve a high efficiency of Zn(II) ions removal from the effluent. FTIR revealed that OH, C=C, C=O, C–H, C–N, and NH groups were the main biosorption sites for metal ions.

The sorption properties of Shewanella xiamenensis biofilm formed on zeolite (mineral-organic sorbent) as a sorbent have been investigated aiming to determine its suitability for complex zinc-containing effluent treatment. The optimum conditions for metal sorption from synthetic solutions were evaluated by changing the pH, zinc concentration, temperature, and time of sorption. The highest removal of metal ions was attained at pH range 3.0–6.0 within 60–150 min of sorbent-sorbate contact. The results obtained from the equilibrium studies were described using the Langmuir, Freundlich, and Temkin models. Maximum sorption capacity of the sorbent calculated from the Langmuir model changed from 3.4 to 6.5 mg/g. High coefficient of determination values calculated for pseudo-second-order and Elovich models indicate the predominant role of chemisorption in metal removal. Gibbs energy and ∆H° values point at the spontaneous and endothermic character of the sorption. The effect of pH and biosorbent mass on Zn(II) sorption from industrial effluent with an initial Zn(II) concentration of 52.8 mg/L was tested. Maximum removal of zinc ions (85%) was achieved at pH 6.0 by applying a two-step treatment system.

This study discusses contamination of soils and sediments with trace elements such as Mn, Ba, W, V, Co, Cr, Zn, Ni, As, Sb Hg as well as Th and U, the influence of natural and anthropogenic factors on the distribution of elements and the ecological state of the Zarafshon Valley. The elemental composition of 116 soil and sediment samples were analyzed by the neutron activation analysis. The calculation of the geoaccumulation index (Igeo), contamination factor (CF) and pollution load index (PLI) showed that some places in the investigated region with developed the industrial zones (around mining and processing plants of “Anzob”, “Konchoch”, “Kumargi bolo” and “Mogiyon”) are mostly polluted by As, Sb, Hg, and in rare cases, the high concentration of W and V were determined. In addition, they were considered the distribution of radioactive elements–thorium and uranium and their ratio in the soil and sediments. Moreover, in the investigated area, strong anomalies of Th and U were not found. It turned out that the content of Th and U are local in nature and do not have a noticeable effect on the environment.