The objective of the HiPur project was to investigate the suitability of filter sands for the adsorption of H2S as well as the economic potential analysis for application as a gas cleaning agent in biogas plants.
The higher-grade use of water residues to treat gases (HiPur) project is a research project funded by the German Federal Environmental Foundation (DBU) and conducted in cooperation with DBI Gas- und Umwelttechnik GmbH, Technologiezentrum Wasser in Karlsruhe (German Water Centre, TZW) and Hamburger Wasserwerke GmbH (Hamburg Water Works).
As part of the project and to achieve the set objectives, filter sand from the iron removal/manganese removal step of different water treatment plants in Germany was analysed for its H2S adsorption capacity. To achieve the necessary comparability, the sands were first prepared in a standardised procedure (drying, grinding, fractionation according to grain size) and then the H2S adsorption behaviour was tested in breakthrough experiments. The loading capacities achieved were used to rank the materials. Approx. 40 % of the investigated sands showed good to very good adsorption properties.
In a second step, the physical and chemical properties were investigated and correlated with the obtained loading capacities. Mercury porosimetry, the temperature-programmed desorption of ammonia, the analysis of the specific surface using BET, X-ray diffractometry, and Raman spectroscopy were used as methods of analysis. A significant link became clear between density and adsorption capacity.
More in-depth studies provided information on how to transfer this approach to real conditions, necessary treatment methods for the sands, the behaviour to other trace gases and the possibility of regenerating H2S-loaded materials. It was shown that the sands could be used in their original grain size, although drying is recommended.
The market potential of the materials was also assessed in the project. This was based on site-based data on the generation of residues (water treatment plants) and potential customers for the adsorbents (regenerative gas producers). Researchers developed scenarios on the generation of sand and on the potential demand. These scenarios were processed and evaluated in a geoinformation system. It was shown that filter sands, as a cost-effective niche product, have promising sales potential and can be recycled regionally and in an environmentally friendly manner as a result of the regional proximity of water works and biogas plants.
The project indicated the higher-grade use of filter sands as a gas cleaning agent in biogas plants as a promising application. A series of questions arose during the project, in particular related to the industrial implementation under real conditions and so a further project should carry out field tests on real facilities.
Raabe T., Schuhmann E., Krause H., Lipp P., Dammann E.: Nutzung von Wasserrückständen zur Aufbereitung von regenerativen Gasen [Use of water residues to treat regenerative gases]. energie | wasser-praxis (No. 5/2018) p. 60-63
Witzig C., Müller Y. K., Pittroff M., Lipp P., Sacher F., Zumbülte N.: Untersuchung von zur Gasaufbereitung geeigneten Filtersanden aus der Wasseraufbereitung mittels Raman-Mikrospektroskopie [Analysis of the suitability of filter sands from water treatment for the treatment of gas using Raman microspectroscopy]. Poster at the annual meeting of the Water Chemical Society, Erfurt, May 2019
Lipp P., Birkner C.: Höherwertige Nutzung von Filtersand aus der Trinkwasseraufbereitung zur Entschwefelung von Gasen (HiPur) [Higher-grade use of filter sand from drinking water treatment for the desulphurisation of gases (HiPur)]. Presentation at the Water Treatment Forum, Mülheim an der Ruhr, November 2019
Lipp P.: Höherwertige Nutzung von Filtersand aus der Trinkwasseraufbereitung zur Entschwefelung von Gasen. [Higher-grade use of filter sand from drinking water treatment to desulphurise gases]. Presentation at the Water Innovation Forum at the gat/wat in Cologne, November 2019