Abstract:
The subject of our study involved the treatment of real process wastewater from the production of rayon fiber. During the annual monitoring of the production facility, we performed a mass balance of three problematic sources of process wastewater and analyzed them repeatedly. All three sources showed high values of COD = 0.4-30 g/L, TOC = 0.09-7.1 g/L and the concentration of Zn2+ 0.09-0.5 g/L. At a total volume of 1.84 million m3, this represents a significant pollution source for the Elbe River. At lab-scale, we tested a combination of filtration, microfiltration, and oxidation using the Fenton, electro-assisted Fenton, and the electrochemical oxidation methods, both on the plate and newly developed macroporous BDD electrodes on a ceramic substrate, along with the final adsorption of Zn2+ emissions on the strongly acidic cation exchange resin Lewatit Mono plus S108. It was tested in Na+ and H+ cycles. Using an optimized technological sequence, we have achieved a COD reduction of up to 98%, and a TOC reduction of 85%. During the H+ cycle cation regeneration by sulfuric acid, Zn2+ emissions were converted to zinc sulfate that can be recycled in the spinning bath of the production process. The method was verified at a pilot scale.