11.3 Pharmaceutical residues removal

The accumulation of pharmaceutical residues and micro-pollutants in wastewaters in the environment has become a problem of growing concern. Although some compounds are easily biodegradable, many exhibit a strong refractory character which makes conventional biological wastewater treatment ineffective concerning their removal, and these substances furthermore endanger activated sludge performance and pose a health hazard for both aquatic and terrestrial life. The application of gas-phase pulsed electrical discharges (plasma technology) is a promising method for the energy efficient oxidative degradation of aqueous organic pollutants Precursors in oxidative degradation chemistry are reactive oxygen (ROS, e.g. OH·, HO2, O, 1O2, O3, H2O2) and reactive nitrogen species (RNS, e.g. NO, NO2, HaNbOC). These species are generated by plasma operation in humid air. ROS also are produced at the G/L interface, due to direct water bombardment with energetic electrons, excited states and ions. Therefore, optimization of the plasma-water interface by combination of an aqueous hyperbolic vortex with a plasma is expected to strongly benefit the plasma induced oxidative degradation of aqueous priority materials, since these species are expected to be dissolved effectively by the suction and the highly efficient gas absorption properties of the aqueous hyperbolic vortex.

Research challenge
For laminar flows it is known that the OH formation and plasma stability strongly depend on hydrodynamic conditions with the gas-liquid contact surface being a major variable for oxidation energy efficiency. A combination of plasma discharges and hyperbolic vortex for continuous flow-through operation will thus have to be tested in terms of viability, scalability and optimum operation parameters. The student will build on the existing knowledge about flow regimes and aeration capabilities of a hyperbolic vortex on the one side, and on the knowledge about pulsed plasma discharge disinfection on the other side. Testing different plasma / vortex combinations concerning their effectiveness in destroying pharmaceutical residues will be achieved by a conducting a designed experiment which will involve a number of tunable physical and chemical parameters including (but not limited to) flow rate, temperature, plasma energy density (includes power, frequency and volumetric flow rate), voltage waveform, electrode configuration, , electrode shape and material, type of pharmaceutical residue, gas phase composition (incl. plasma buffer gases), vortex size (fluid dynamics mixing parameters), pH and conductivity, BOD/COD, microbiological toxicity assays (to test the effectiveness of oxidative degradation).

We are looking for an excellent, highly motivated and enthusiastic researcher with an MSc degree in the field of physics, chemistry, physical chemistry with affinity for water technology/process engineering. Adequate experimental and theoretical skills are required. Candidates with experience in high voltage / plasma research are preferred. Knowledge of computational fluid dynamics is a plus. Organizational and communication skills are required in order to facilitate interaction with several external parties.

The research project is part of the Wetsus research theme Applied Water Physics.
The following companies are part of the theme:

- Brabant Water
- Coherent Water Systems
- Bright Spark
- IPF/Grander
- Schauberger Natur Technik
- Integro
- Waterschap De Dommel

Promotor: Dr.Ir.W.F.L.M. (Wilfred) Hoeben, TU Eindhoven, delegated by A.J.M. Pemen, TU/e full professor and EES chair.
Co-promotor: Prof. Dr. Jakob Woisetschläger, TU Graz
Wetsus supervisors: Dr. Luewton L.F. Agostinho, Dr. Elmar C. Fuchs

Wetsus, Leeuwarden, The Netherlands

combining scientific excellence with commercial relevance