The paper investigates the use of cress (Zabava and Krupnolistovoi varieties) and wheat (Salavat Yulaev and Omskaya varieties) as phytoecological indicators. The object for testing was still waste liquid, the main waste of soda ash production. The toxicity was assessed by three parameters (seed germination, length and dry weight of the seedlings). It is shown that the still waste liquid has an acute toxic effect on all phytoecological indicators used. It has been found that the regression equations for seed germination and dry weight of seedlings in contrast to their average length for all plants do not adequately describe the experimental results and can not be used to evaluate the safe dilution factor. The safe dilution factor, determined by the average length of the seedlings, for cress Zabava is 34.7 and cress Krupnolistovoi is 34.4, and for wheat Salavat Yulaev is 73.0 and for wheat Omskaya is 81.8. It was established that the safe dilution factor determined with the use of different plant species varies quite strongly.

No abstract

No abstract

The paper presents the study results for the treatment of sulfide wastewater generated by tanneries. Wastewater treatment was carried out by electrolysis with a sacrificial ferrous anode. It is shown that during the treatment process, the ferrous anode dissolves and deposition of iron sulfide is formed. The process of effluent treatment is determined by the anode current density. The most efficient effluent treatment is carried out at a current density of 133 A/m2. In this case, the purification efficiency reaches 99.2%, and the cost per unit of electricity makes 169.2 kW·h/kg.

The article presents results of researches on treatment of spent acid etching solution (SAES) formed during etching of titanium products by hydrochloric acid. The process includes neutralization of SAES with alkali, filtering, drying and calcinations of titanium hydroxide precipitate and electrochemical processing of the filtrate containing sodium chloride in a cell with ion exchange membranes. During electrolysis, sodium hydroxide and hydrochloric acid are produced. The proposed process scheme of SAES treatment allows to obtain titanium dioxide, sodium hydroxide and acid. Titanium dioxide can be used in paint and coatings industry. Alkali can be used in SAES neutralization process. The acid is suitable for use in etching process of titanium products.