Abstract
This paper presents the study of the possibility to increase the extraction degree of heavy metal ions (HMIs) from two types of galvanic wastewater (GWW 1 and GWW 2) by the reagent method. It is established that, as a result of interaction between GWW 1 components and Na2S pentahydrate, the largest amounts of the resultant precipitate were registered in alkaline medium, which is 13.4 and 91.5% greater than in neutral and acidic media, respectively. A greater precipitate weight increase was observed when using 0.7% of Na2S pentahydrate in alkaline medium than when using 0.14% of that solution. The following efficient conditions are determined for removing HMIs from GWW 1 by the reagent method: Na2S pentahydrate solution concentration of 0.7%; volumetric reagent/GWW ratio: 1:42; alkaline medium; and retention time of 20 minutes. Implementing the method proposed allows achieving the extraction degree of 99.97% for Cu2+ ions and 99.93% for Ni2+ ions. A greater efficiency of extracting HMIs from GWW 2 was identified with adding Na2CO3, as compared to Ca(OH)2 when depositing for 25 minutes. Implementing the technique proposed for cleaning of GWW 1, GWW 2 from HMIs leads to achieving the standards of threshold limit values for fishery water bodies.
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