One-dimensional soil columns
Different types of soil columns are used to simulate various infiltration scenarios as well as to characterize clogging, biodegradation and oxygen dynamic processes that occur during MAR operation. The column type and the experimental setup depends on the objectives of investigation.
Small-scale soil columns
1D plexiglas columns with a length of 49.5 cm and a diameter of 4 cm and filled with soil material are used to investigate processes that take place during water percolation through unsaturated soil zone. Therefore, different water types with different quality can be infiltrated with different hydraulic loading rates in alternating wetting / drying phases. To prevent the discharge of fine material from the soil material, a porous teflon plate is usually installed at the lower end. The temporal changes in infiltration capacity are characterised by tests with conventional environmental tracers.
Mid-scale soil columns
1D PVC-column with a length of 1.00 m and a diameter of 0.15 m and filled with soil material is used to simulate different infiltration scenarios during operation of MAR. In order to prevent the discharge of fine material from the soil material, a gravel filter layer is installed at the lower end. For the measurements of spatial and temporal distribution of the soil moisture, tensiometers (UIT GmbH) are installed at different depths (currently in three levels at 0.16 m, 0.28 m and 0.68 m) below soil surface. Additionally, fiber-oxygen sensors (Pyroscience GmbH) are installed to measure oxygen dynamic within the system. An electronic scale is placed at the outlet of the tank to determine the discharge of water over time. The unit is placed inside of a fully automatic climate tent, which facilitates the exact control of air temperature and humidity. Different water types with different quality can be infiltrated with different hydraulic loading rates and with alternating wetting and drying phases. The system can be further customised acording to the project objectives.