RADAR: Wastewater Treatment by OH-Radicals

The protection of water resources and the reduction of all wastewater emissions require a closed-loop cycle for (process) water streams or an effective treatment of the wastewater. The problem with industrial and other water streams is the accumulation of impurities which need to be removed. In this project, an electrochemical process is being developed which mineralizes organic substances to a great extent. Especially non-biodegradable compounds, toxic ingredients and endocrine disruptors can be eliminated with this method. Being strong oxidizing agents, the OH radicals used can completely mineralize these substance classes.

Objective

Within the project scope it is intended to promote the mineralization of hard-to-treat organic contaminants such as aliphatic compounds, active substances and x-ray contrast agents in wastewater  by using a combination of in situ reactions with hydrogen peroxide (H₂O₂) and OH radicals in a novel electrochemical cell with a boron-doped diamond electrode (BDD) as anode and a gas diffusion electrode (GDE) as cathode. Strong oxidizing agents are formed on the anode (OH radicals) as well as on the cathode (H2O2). This new combination generates additional oxidation reactions that increase the electrochemical yield and improve the overall degradation efficiency of water purification.

Focus of work

The implementation of the new process on a technical scale requires the following research and development work:

• GDE design (catalyst, additives, carrier materials, pore structure, stability, production)
• Production of BDD electrodes and scale-up of their manufacturing process
• Material development and production of auxiliary electrodes / flexible electrodes against scaling
• Scalable cell design for synergetic operation of the new GDE / BDD
• Comparison of different basic cell concepts
• Optimization of the cell design to avoid scaling, precipitation and separation of Ca/Mg compounds in order to address water hardness.
• Adaptation of the cell design for different demonstrator applications
• Practical test of an adapted electrolysis cell based on realistic criteria.
• Technology assessment in comparison with other oxidation processes and alternative electrodes
• Testing of the new process on different wastewater qualities
• Ecotoxicological studies and assessment of the technology
• Economic evaluation based on application-relevant parameters such as NRC and LCC