Research

Three lines broader than any single project: the nutrients and contaminants that must come out of the water, the tools for understanding the reactors that do it, and the residue left at the end of the process.

Nutrients, emerging contaminants and N₂O emissions

The nitrogen and phosphorus that must come out of the water, the pharmaceuticals and pesticides that travel with them, and the greenhouse gas that escapes while treating them.

Treating water is not just about lowering a concentration. Nitrogen and phosphorus are removed through biological pathways — nitrification, autotrophic and heterotrophic denitrification, anammox, feammox — and each pathway has its own performance and its own cost. We study them in suspended-biomass and biofilm reactors, with carriers such as elemental sulfur and Chilean natural zeolite, in groundwater as well as wastewater.

Emerging contaminants arrive alongside the nutrients: antibiotics, anti-inflammatories, herbicides, aromatic hydrocarbons. They appear at concentrations of micrograms per litre, and their fate inside a biological reactor — how much is degraded, how much is adsorbed, how much passes straight through — is far from settled.

The third front is the one usually left out of the balance: nitrous oxide. It is an intermediate product of denitrification, has nearly three hundred times the warming potential of CO₂ and also depletes stratospheric ozone. We measure how much is emitted and how that emission changes when emerging contaminants are present, something on which almost no data exist today.

Keywords

  • Nitrification
  • Autotrophic denitrification
  • Anammox and feammox
  • Pharmaceuticals and pesticides
  • Nitrous oxide
  • Elemental sulfur
  • Natural zeolite

Modelling and simulation of bioreactors and multiphase systems

A reactor is a flow, a biofilm and a reaction happening at once. Simulating it is what explains why it performs the way it does.

A bioreactor’s performance does not depend on kinetics alone. It depends on how the fluid moves between the grains of the bed, where the biofilm forms, how fast the substrate reaches the bacteria. None of that is visible from the outside, and that is exactly what simulation opens up.

We work with computational fluid dynamics coupled to transport and biological kinetics, with real geometries obtained by computed tomography, and with CFD–DEM coupling to track how the medium changes as it is consumed. Validation is part of the method: models are confronted with residence time distributions measured in the reactor, an observable that integrates everything happening inside.

The scope reaches beyond water treatment reactors: the same multiphase flows appear in gas biofiltration, in porous media colonised by biofilm and in anaerobic digestion. The horizon is a digital twin of the reactor: a model you can operate and scale with, instead of tuning by trial and error.

Keywords

  • CFD
  • OpenFOAM
  • CFD–DEM
  • Computed tomography
  • Residence time distribution
  • Multiphase flow
  • Digital twins

Sludge treatment: microaeration and anaerobic digestion

Sludge is the residue of water treatment and, at the same time, a source of energy and nutrients. The difference lies in the pretreatment.

A wastewater treatment plant produces sludge, and that sludge is its biggest handling problem: it leaves the process with very high moisture, which drives up transport and disposal costs. But it also holds organic matter that can become biogas, and nutrients that can be recovered.

We work on the pretreatments that change that equation. Microaeration — controlled doses of oxygen in an anaerobic environment — improves hydrolysis and subsequent dewatering. Anaerobic digestion turns organic matter into methane and hydrogen, and its performance depends on the substrate mixture, the available micronutrients and process stability: all of which can be modelled. Biodrying, in parallel, uses the heat of the biological activity itself to dry the sludge.

The liquid separated from the sludge is not treated as waste either: it is a concentrated stream from which nitrogen and phosphorus can be recovered. That is where the group’s three lines meet — nutrient removal, process modelling and waste valorisation — and where circular economy stops being a slogan and becomes a mass balance.

Keywords

  • Anaerobic digestion
  • Microaeration
  • Biodrying
  • Sludge dewatering
  • Biogas and bioH₂
  • N and P recovery
  • Circular economy