No abstract

This paper presents the possibility of using sodium trithiocarbonate to remove heavy metals such as copper, nickel, and tin from industrial wastewater generated by the production of printed circuit boards (PCBs). Initial metal removal studies aimed at selecting an effective precipitant and optimizing the precipitation process were conducted on an laboratory scale. The smallest concentrations of copper, nickel, and tin in treated wastewater (Cu 0.09 mg/L, Ni 0.009 mg/L, Sn <0.005 mg/L) were obtained after using a stoichiometric sodium trithiocarbonate dose at pH 9.0-9.5. Optimizing the metal removal process was possible by using the surface response method to obtain a good adjustment of the experimental data to the data obtained from the model (R 2 = 0.9307, R 2 adj. = 0.8845). The results of laboratory and model studies were used during industrial-scale testing in a wastewater treatment plant located in a PCB manufacturing plant. Optimization the wastewater treatment process on an industrial scale allowed us to obtain treated wastewater with very low copper (<0.005-0.014 mg/L), nickel (<0.005-0.008 mg/L), and tin (<0.005 mg/L) concentrations.

During a study aiming to recover strategic elements and minerals from coal fly ash and bottom ash (RAREASH and CHARPHITE projects funded, respectively, by the 2nd ERA-MIN and 3rd ERA-MIN Programs of the European Union Commission), it was found that in coal fly ash and bottom ash from Romania and Poland, several morphotypes did not fit into the general fly ash classifications, unless grouped together as "undifferentiated inorganics". However, the combination of reflected light optical microscopy under oil immersion, scanning electron microscopy, and X-ray microanalysis (SEM/EDS) showed that many of these morphotypes not only have distinctive petrographic patterns but are also characterized by a chemical assemblage dominated by Ca, Mg, and P. In this paper, a survey of the literature is presented together with several detailed studies of samples from the RAREASH and CHARPHITE projects from which the following nomenclature are proposed: "calcispheres" for spongy Ca-rich morphotypes, "calcimagnesiaspheres" for (Ca + Mg)-rich morphotypes with visible MgO nodules and/or periclase (MgO) exsolved from Ca aluminate-silicate glass, and "magnesiaspheres" divided into "magnesiaferrospheres" for (Mg + Fe)-rich morphotypes with magnesioferrite, and "magnesiaoxyspheres" for magnesiaspheres mainly composed of (Mg + Fe)-rich amorphous material with visible MgO nodules and/or periclase.

Abstract:The possibility of removing organic compounds from wastewater originating from the photochemical production of printed circuit boards by use of waste acidifi cation and disposal of precipitated photopolymer in the fi rst stage and the UV-Fenton method in a second stage has been presented. To optimize the process of advanced oxidation, the RSM (Response Surface Methodology) for three independent factors was applied, i.e. pH, the concentration of Fe(II) and H 2 O 2 concentration. The use of optimized values of individual parameters in the process of wastewater treatment caused a decrease in the concentration of the organic compounds denoted as COD by approx. 87% in the fi rst stage and approx. 98% after application of both processes. Precipitation and the decomposition of organic compounds was associated with a decrease of wastewater COD to below 100 mg O 2 /L whereas the initial value was 5550 mg O 2 /L. Decomposition of organic compounds and verifi cation of the developed model of photopolymers removal was also carried out with use of alternative H 2 O 2 sources i.e. CaO 2 , MgO 2 , and Na 2 CO 3 ·1,5H 2 O 2 .

Coal ash char concentrates from four countries (Portugal, Poland, Romania, and South Africa) were prepared, characterised, and graphitized under the scope of the Charphite project (Third ERA-MIN Joint Call (2015) on the Sustainable Supply of Raw Materials in Europe). Coal ash chars may be a secondary raw material to produce synthetic graphite and could be an alternative to natural graphite, which is a commodity with a high supply risk. The char concentrates and the graphitized material derived from the char concentrates were characterised using proximate analysis, X-ray fluorescence, X-ray diffraction (structural), Raman microspectroscopy, solid-state nuclear magnetic resonance, scanning electron microscopy, and petrographic analyses to determine if the graphitization of the char was successful, and which char properties enhanced or hindered graphitization. Char concentrates with a lower proportion of anisotropic particles and a higher proportion of mixed porous particles showed greater degrees of graphitization. It is curious to see that embedded Al2O3 minerals, such as glass and clay, influenced graphitization, as they most likely acted as catalysts for crystal growth in the basal direction. However, the graphitized samples, as a whole, do not compare well against a reference natural graphite sample despite some particles in select char concentrates appearing to be graphitized following graphitization.