Vol 41, No 1 (2019)

A reliable quantitative assessment of the quality of river waters is difficult due to high variability of indexes being controlled and absence of information about the empirical function of the distribution of their probabilities. It is shown that in such a situation the expert-statistical method based on probabilistic interpretation of different variants of the Harrington desirability function may be useful. Such an approach makes is possible to solve the set problem using the Harrington scale for individual pollutants and for their combination with different hazard classes using a complex multiplicative criterion. The proposed approach of the expert-statistical assessment is illustrated by a practical example which may be recommended for general use.

The article investigates kinetics of electrocatalytic oxidation of phenol in the solution of sodium sulfate on a platinum electrode in the presence of dispersed oxides of metals of varied valence. It is shown that the degree of phenol oxidation in the presence of oxides increase by 10–15%. The most active catalysts include oxides of cobalt, chromium, copper and titanium, whose catalytic activity diminishes in the series Co₃O₄ > Cr₂O₃ > Cr₂O₃ > TiO₂ > CuO; the rate of electrooxidation of phenol increases at a decrease of anolyte. It was shown that a limiting stage of electrochemical oxidation of phenol in aqueous solutions with the concentration 50 mg/dm³ is a diffusion of the substance to the electrode.

Antimony is an environmental pollutant categorized as metalloids. The biosorption of Sb(III) ions from aqueous solutions investigated by Sargassum glaucescens brown alga seaweed in a fixed bed column. Column experiments were carried out to evaluate the effect of bed height and flow rate on the biosorption process and to obtain the experimental breakthrough curves. The highest biosorption capacity of S. glaucescens for Sb (III), was 5.89 mg/g found within a flow rate of 8 mL/min and a bed height of 15 cm. Furthermore, it was observed that by increasing the bed height the breakthrough and exhaustion times increased, while these times reduced as the flow rate rises. The column data obtained under different conditions were fitted to the Yan and Bed Depth Service Time models, which coefficient correlations obtained from Yan’s model, were found to be satisfactory. Biosorption-desorption experimental data were evaluated by one-way ANOVA and one-sample t-test methods to investigate the statistical importance of uptake capacities after three cycles for five desorbents.

Paper bleaching effluent was treated by catalytic wet oxidation method and the effect of the type of the catalyst on the efficiency was investigated. Cerium oxide, cobalt oxide and copper oxide based (CuO_x-CoO_x-CeO₂) composite catalysts which were varying with regard to CuO_x, CoO_x and CeO₂ compositions were prepared by co-precipitation method. The efficiency of the process was determined by measuring the chemical oxygen demand (COD), total organic carbon (TOC), adsorbable organic halides (AOX) and Cl⁻ removal yields. When the COD, TOC and AOX removal yields were considered, better results were achieved with copper and ceria based catalysts than the cobalt based catalysts. At the optimum reaction conditions (T—473 K, t—120 min, P—130–250 psig), the maximum removal yields obtained by the 50% CuO_x–50% CeO₂ catalyst. When the wastewater of the I stage of paper bleaching process was treated, removal yields of TOC, COD and AOX were detected as 89; 94 and 95%, respectively Whereas, removal yields of 53% COD, 84% TOC, 90% AOX and 76% Cl⁻ were achieved for the III stage wastewater. It was shown that removal of the toxicity of wastewater samples that were collected from the paper bleaching process by the proposed treatment methods.

We have developed a mobile design of a bioplato for purification of water objects of heavy metals and determined promising moisture-resistant high land plants—thymophyry and rye, which allow us to achieve the maximum effect of water purification. A comparative study of the efficiency of purification by plant-hyperaccumulators using the example of Zn(II) and Cd(II) ions was carried out. A direct relationship between the efficiency of rhizosorption and the density plant growth in the hydrophytic system was established.

This study shows the possibility of applying the complex bioassay of water to determine the degree of its toxicity under conditions of microbiological contamination. The toxic effect of microorganisms (Candida albicans) at their density 1 × 10² CFU/cm³ was detected on fish cells using the micronucleus test method. The possible mechanisms of toxic effect of enhanced microbial contamination of water on animal and plant test-organisms have been studied.