Situation: | Elevated nitrate levels in water bodies, especially in groundwater, are a global problem for drinking water supplies (World Health Organization 2011; Mohseni-Bandpi et al. 2013). Due to its carcinogenic properties and the risk of causing methemoglobinaemia, the recommendations of the World Health Organization (WHO) and the European Economic Community (EEC) are based on a drinking water limit of 50 mg NO3-/l, which is also included in the German Drinking Water Ordinance (TrinkwV; World Health Organization 2011). Various treatment techniques can be used to remove nitrate from drinking water, such as reverse osmosis, ion exchange, electrodialysis and biological denitrification. Biological treatment is increasingly coming into focus, as it offers a high level of water recovery at moderate costs through the complete and selective reduction of nitrate to nitrogen compared to physico-chemical processes (Rezvani et al. 2019). Biological denitrification can be divided into auto- and heterotrophic denitrification. Heterotrophic denitrification is generally applied in wastewater treatment. Here, readily biodegradable organic carbon sources are needed, which, however, can pose a hygienic risk in drinking water treatment due to accelerated rapid growth of microorganisms. The autotrophic denitrification uses inorganic carbon such as CO2 only, this method is preferable for drinking water treatment, especially for groundwater (Rezvani et al. 2019). In recent years, bioelectrochemical systems (BES) are increasingly discussed with regard to biological denitrification (Cecconet et al. 2018; Rezvani et al. 2019). |
| Methodology: | The goal of this project is the development of an autotrophic denitrifying bioelectrochemical system for drinking water treatment. The focus is on the search for suitable cathode materials and their shapes, which are able to act as electron donors and suitable habitats for microorganisms. The process will be investigated with respect to its stability, relevant boundary conditions and challenges for implementation. Initially simple batch tests were designed in order to identify main influencing parameters and optimize the fundamental processes in an innovative reactor setup. Subsequently, this experimental setup is carried out with different electrode materials and varying material properties and shapes. On basis of batch results, a continuous bioelectrical reactor systems shall be constructed. |
