The SeWieBorG – Phase 1 project addresses the persistent problem of boron emissions from the production of boron‑containing glasses such as C‑glass, E‑glass, specialty glass, economic glass and enamel. In these processes, both particulate and gaseous boron species are released, yet conventional dry‑filtration methods fail to capture the gaseous fraction efficiently. Because boric acid and borates are classified under EU Regulation 1272/2008/EG as hazardous substances, and because they have documented adverse effects on plants and animals, an effective removal strategy is urgently required.
The project’s technical concept combines an alkaline washing step with ion‑exchange treatment. In the alkaline wash, gas‑phase boron is converted to sodium borate, which, due to a five‑fold difference in solubility between boric acid and sodium borate, can be precipitated by acidification and separated from the gas stream. The recovered boron is then concentrated for potential reuse. The remaining boron‑laden wastewater is treated in a column of ion‑exchange resin to achieve a safe level for discharge into the sewer system.
Field experiments were carried out at the Schott AG site in Mitterteich. A test washer was installed to evaluate the separation of gaseous and particulate boron from the exhaust stream. Parallel laboratory work was performed at ALR Umwelt, where several ion‑exchange resins were screened using synthetic wastewater until breakthrough, followed by regeneration. The most promising resins were then challenged with real process wastewater collected from the Schott plant.
Five resins were investigated: Amberlite IRA 78, Amberlite IRA 743, Purolite S108, Ambersep 800 OH, and Diaion CRB 05. Breakthrough volumes and pH behaviour were recorded for each resin. For column A (Amberlite IRA 78) breakthrough occurred at 75.5 L during the first adsorption run with synthetic wastewater, and at 50 L and 70 L in subsequent runs. When real wastewater was used, breakthrough was reached after only 5 L, accompanied by a pronounced drop in pH from about 12 to 9.5. Column B (Amberlite IRA 743) showed breakthrough at 14.75 L for the second synthetic run and at 18.5 L for real wastewater, with pH decreasing from roughly 7 to 4.5 and from 9 to 7, respectively. Column C (Purolite S108) exhibited breakthrough at 16.25 L for the second synthetic run and at 22.25 L and 19.25 L for the two real‑water runs; here the pH change was less pronounced. Across all columns, the pH trend provided a general indication of resin loading, but the shift often lagged behind the actual breakthrough and was not always sufficiently sharp to serve as a reliable real‑time indicator.
The results demonstrate that ion‑exchange resins can effectively remove boron from process wastewater, but the performance depends strongly on the resin type, the composition of the wastewater, and the operating conditions. The alkaline wash step successfully captures gaseous boron, while the ion‑exchange columns achieve substantial boron removal, albeit with varying breakthrough capacities.
The collaboration involved Schott AG, which supplied the industrial site and real‑world wastewater samples, and ALR Umwelt, which conducted the laboratory screening and detailed analytical work. The project was carried out over the course of Phase I, with the field tests and laboratory experiments overlapping to allow rapid iteration between pilot‑scale observations and bench‑scale optimisation. Funding for the project was provided by a European research programme focused on hazardous substance mitigation, underscoring the environmental relevance of the work. The final report consolidates the experimental data, discusses the limitations of pH as a loading indicator, and outlines the next steps for scaling up the combined washing and ion‑exchange approach to achieve compliant emissions from boron‑glass manufacturing.