Thermochemical processing of non-recyclable waste streams

By EU waste policy, an irreversible treatment of non-recyclable waste through thermal processing (i.e., incineration or gasification) is mandatory to keep intended cycles of materials in the Circular Economy clean and safe. This way, the energetic content of the waste can be largely recovered in the form of electricity, steam/heat, energy carriers (syngas) and/or valuable organic compounds, whilst toxic organic compounds are destroyed. It also creates opportunities for advanced recovery of inorganic materials and compounds of high interest from the ashes generated. However, when waste is exposed to high-temperature environments in thermal processes, the inorganics present in the waste exhibit a complex behavior by which they are distributed over solid, gas and liquid outputs. In state-of-the-art thermal processing plants for non-recyclable waste, the behavior of inorganics is still highly uncontrolled and provokes significant operational problems. It also poses challenges in view of increasing yields of energy and materials from the waste treated, reducing chemicals for treatment of flue gasses and residues generated, and implementing carbon capture technologies.

The objective of this PhD project is to develop an in-depth understanding of the complex multiphase behavior of inorganic compounds present in (selected) wastes when gasified or incinerated. The PhD project mainly comprises experimental work and aims at unravelling the influence of physical process conditions imposed (in terms of temperature, pressure, flow, and induced heat and mass transfer) on chemical effects observed. A thermal waste reactor at the pilot-scale, equipped with advanced analytical equipment, will be used to research different types of waste under industrially representative process conditions and temperatures up to 1250°C. Examples of waste types of interest are: tyre rubbers (containing Zn and Mg), brominated flame retardant plastics (Br and Sb), anti-microbial packaging materials and textiles (Ag and Cu), pruning wood from vineyards (Cu and S), CCA-treated wood (Cu, Cr and As) and sewage sludge from municipal waste water treatment (P). The PhD is partially funded by leading companies in the European Waste-to-Energy industry. The work will be executed in close interaction with universities from Ljubljana and Budapest, which opens up the possibility for a stay abroad.

Expected results:

- Start-up and exploration of a new, pilot-scale, thermal waste reactor in the lab;

- Establishment of a coherent and qualitative set of experimental data;

- Elucidation of correlations between physical conditions applied and chemical effects observed;

- Multiple (2-3) Scientific publications;

- Application for a PhD scholarship;

- PhD dissertation.

The person in this position is also expected to carry out educational tasks for about 10-15% of his/her time.