Viability of two alternatives for treating waste solutions from the biomachining process

Biotechnology is currently playing an important role in sustainable development, and advances in this field are, in fact, among today's most cutting-edge scientific contributions. Nevertheless, they are not free from waste generation. This research studies the viability of two alternatives for treating the depleted solutions obtained in the biomachining of copper pieces, paying special attention to the recovery of copper. The precipitation alternative of increasing the pH value required the preliminary oxidation of Fe2+, iron precipitation and filtration, and finally, Cu precipitation (as CuO) and filtration. The recovery was quantitative but time-consuming, and the reagent's overall cost was 1.69 (sic)/L. The electrorecovery alternative also required the oxidation and precipitation of iron before copper deposition (as Cu-0) at a constant voltage. This deposition was also quantitative, but faster than the recovery at a constant current (14 min versus 20 min). The reagent's cost was 1.54 (sic)/L, and the copper electrodeposition's energy cost was 3.6 times lower than the cost of the raw metal, which made the electrochemical treatment viable, affordable and sustainable. (C) 2020 Elsevier Ltd. All rights reserved.