The project consortium pursued the vision of reuse industrial water flows as completely as possible in order to relieve natural water resources. The task of TZW was the development of an online process monitoring for organic trace substances in highly saline matrices.
Increasing water scarcity increases the need to reuse saline water and to recycle the removed constituents at the same time. Currently, more than 6 million tons of chloride are discharged annually into surface waters via wastewater in Germany. Process wastewater and partial streams of existing treatment processes as well as saline wastewater from stockpiles or saline groundwater are the most relevant sources.
The overall objective of the project was to establish a sound decision-making basis for the implementation of salt and water recovery processes on a production scale.
The work of TZW was concerned with the aspects of monitoring and quality assurance and comprises two focal points:
Analytical online methods using ion chromatography (TZW Karlsruhe):
For the recycling of highly saline water from polymer production for chlor-alkali electrolysis, certain quality parameters must be maintained. In particular, the contents of specific organic impurities (e. g. ionic nitrogen compounds) must be below critical levels, otherwise the downstream process is jeopardized. In the already completed Re-Salt project (BMBF), ion chromatography with conductivity detection was found to be the best method for online analysis of this parameter (IC-CD) after interfering components (sodium ions) were effectively separated via a special online solid phase extraction. In the RIKovery project, the existing laboratory method was upgraded into an online method that analyzes this important quality parameter automatically in the production plant. Online ion chromatography was successfully tested in the final phase of the project as part of an on-site measurement campaign at a Covestro site.
Automated UV and fluorescence measurements in salt water matrix for the detection of aromatic compounds in process water (TZW Dresden):
The aim of the sub-work package was to develop methods for the detection of aniline, phenol and bisphenol A using optical spectrometry. TZW Dresden has many years of expertise in absorption and fluorescence spectroscopy as well as chemometric data evaluation. In the completed Re-Salt project, the feasibility in principle for the detection of the three compounds mentioned by means of absorption and fluorescence spectroscopy has already been demonstrated. Within the framework of the RIKovery project, the methodology was then developed and converted into a process-suitable method. The measurement technique was combined with machine learning methods.
Publications:
O. Happel, Y. Schießer, S. Bieber, T. Letzel, M. Wagner, D. Armbruster, B. Schmutz, General concepts for the analysis of organic compunds in saline waters, Filtrieren & Separieren - Internationale Edition, 2024, 65-67.
O. Happel, Y. Schießer, S. Bieber, T. Letzel, M. Wagner, D. Armbruster, B. Schmutz, Analytical approaches in the RIKovery project, Filtrieren & Separieren - Internationale Edition, 2024, 68-70.
O. Happel, Y. Schießer, S. Bieber, T. Letzel, M. Wagner, D. Armbruster, B. Schmutz, Target- und Non-Target-Analytik in stark salzhaltigen Prozesswässern, Vom Wasser, 2025 (in press).
