Seasonal heat storage in the soil

Applied Science

Biologische sedimentatie van gesuspendeerd slib en sedimentstabilisatie

In het kader van het Delft cluster onderzoeksprogramma Wetlands onderzoekt ‘Biotools’ methoden om de concentratie gesuspendeerd materiaal in een zoetwateromgeving versneld te laten bezinken door toevoeging van biologische additieven (biosedimentatie) en polysacchariden die flocculatie teweeg brengen waardoor gesuspendeerd slib sneller bezinkt (bioflocculatie). In de proefopzet werden 4 varianten vergeleken met de blanco (slib zonder verdere toevoeging): toevoeging van waterzuiveringsslib, toevoeging van een hogere concentratie waterzuiveringsslib, toevoeging van kationische en toevoeging van anionische polysacchariden. De eerste twee varianten zorgen initieel voor een snellere (bio)sedimentatie. De varianten met geladen polymeren zorgen voor uiteenlopende effecten: algengroei trad (sneller) op en kationen zorgen voor een dispersie van kleilamellen waardoor het materiaal langer in suspensie blijft en trager bezinkt. Behalve de initiële bezinksnelheid en concentratie bij evenwicht werd ook gekeken naar de effecten in de tijd. De proevenreeks duurde 11 dagen, en in de loop van de tijd ging de bezinksnelheid in alle proeven omlaag (minst in de blanco, maar de absolute bezinksnelheid was niet de minste van alle proeven in het begin)

Modelling Biogrout: A new ground improvement method based on microbial induced carbonate precipitation

Electrical Engineering, Mathematics and Computer Scienc

A Reactive Transport Model for Biogrout Compared to Experimental Data

Biogrout is a method for reinforcement of granular soil. In the Biogrout process, calcium carbonate is produced. This solid connects the grains, and therefore the strength of the soil is increased. The calcium carbonate is formed with the use of micro-organisms. Experiments and numerical simulations have been performed to demonstrate the process under various conditions. In this paper, it has been examined whether a reactive transport model can be used to describe a Biogrout experiment that was performed in a column with a length of 5 m. Four different models for the course of the reaction rate are considered. The concentration of micro-organisms and the reaction rate are fine-tuned in order to find a description of the experiment that is a best fit for the particular model. This is done by minimizing the error between the experimental and numerical results for the concentration of calcium carbonate and the by-product of the reaction.Delft Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc

Simulation of Front Instabilities in Density-Driven Flow, Using a Reactive Transport Model for Biogrout Combined with a Randomly Distributed Permeability Field

Biogrout is a method to strengthen granular soil, which is based on microbial-induced carbonate precipitation. To model the Biogrout process, a reactive transport model is used. Since high flow rates are undesirable for the Biogrout process, the model equations can be solved with a standard Galerkin finite element method. The Biogrout process involves the injection of dense fluids in the subsurface. In this paper, we present our reactive transport model for Biogrout and use it to simulate an experiment in which a pulse of a dense fluid is injected in a porous medium filled with water. In this experiment, front instabilities were observed in the form of fingers. The numerical simulations showed that the fingering phenomenon was less pronounced than in the experiment. By reducing the dispersion length and implementing a randomly distributed permeability field, the fingering phenomenon could be induced. Furthermore, the results of a case study to a Biogrout application are reported.Delft Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc