'Modeling of reactive setting for wastewater treatment' is the title of the poster presented this Thursday by Romel Pineda Frías, student of the PhD Program in Applied Sciences with a minor in Mathematical Engineering at the Universidad de Concepción, UdeC, in the Expoposter of the contest "Tesis en Tres Minutos" which, year after year, is organized by the Graduate Department of this university. 

In his poster, Romel reports on two partial differential equation models for sedimentation problems that may have applications in wastewater treatment and in the recovery of water resources in the mining industry, among others. “The sequential batch reactor or SBR of this model had already been developed, but only as a system of ordinary equations, or that it was only of interest at an instant of time”, explains the postgraduate student. “So, what we did was model this entire SBR process by adding a new dimension, which is the spatial variable, that is, taking into account the movement of the mobile border of the filling and extraction flows”. 

These works have been developed in the context of Romel's PhD thesis, for which reason they are co-authored by Professors Raimund Bürger (UdeC), Stefan Diehl (Lund Universitet, Sweden) and Julio Careaga (Radboud Universiteit, The Netherlands). 

Prof. Bürger had already studied these models, adapting them to problems with secondary sedimentation, to which, in this new model, Romel explains, “the model was adjusted and we added some functions to be able to improve the simulations and approximate the experimental data in the second poster example”. 

The work of this scientific team has generated a fruitful collaboration that translates into the writing of a series of scientific articles already published and others in preparation. “In the first article”, Romel details, “we developed the governing equations that model this SBR process and in the second article we developed the numerical scheme that satisfies a region-invariant property, which is a desirable property, above all, because it assures us that the simulations that our model will give us will be non-negative and in the case of total solids, it will be bounded, which is very important, for example, in a wastewater treatment plant”. 

Pineda explains that, in addition to this practical application, these models could be used “for the recovery of water resources in mining production processes” and adds that they are currently advancing in their results towards working on “a porous bottom, different from the SBR model, since we are no longer going to have a mobile border, but we are going to have a free border with a constant pressure on the solids so that they filter”. 

The poster that accounts for the main results of this international collaboration is available at this link. Romel Pineda's doctoral studies are financed by the National Doctoral Scholarship of the National Research and Development Agency (ANID-PCHA 2020-21200939).