The system is an automated hydraulic circuit, representing different lithological layers, subjected to treatment using biological and bio-stimulant solutions. The flow in the system is set to simulate a bio-treatment, with flow rates and pressures that can be regulated. The biological treatment that takes place in the system is aimed at the depletion of organic contaminants present in the soil sample. The degradation is carried out by autochthonous microorganism inocula, isolated in soil samples and selected for their ability to degrade recalcitrant molecules, and by stimulated bacteria that are part of the natural ecology of the treated soil. Air or oxygen are injected in the system by means of an air-water mixer. Any produced leachate is recirculated and/or treated.
The process is monitored through sensors inserted in various points of the circuit and this allows to adjust the operation of the system. In this way, in-situ conditions are replicated and kept favorable for bioremediation. Soil and water samples are analyzed every 15 days. Soil chemical analyses are conducted to determine the variation in the concentration of target contaminants, while water analyses have the objective to determine the toxicity of the matrices being treated.
The effectiveness of this innovative technology lies in its ability to establish a filtration flow of the fluid in the entire volume of soil being treated. This pilot simulates the in-situ injection/extraction process and uses a flexible system that allows effective inoculation of biological and chemical solutions, in both saturated and unsaturated soil. Two hydraulic circulation modes can be tested: fluid pressure and gravity force.
The system can hold up to 5 m3 of soil where different lithologies can be tested. This physical pilot can be used to calibrate the corresponding mathematical model to determine the behavior within the soil volume of the following parameters: flow rates, trajectory of the water particles, hydraulic load and pressure.