Modelling of Flow and Transport Processes in Vyredox and Nitredox Subsurface Treatment Plants

Vyredox plants are designed for in situ removal of iron and/or manganese, while Nitredox plants are designed for in situ removal of nitrates and nitrites. Both methods make use of bacteriological processes. A typical unit of a Vyredox plant comprises several injection wells, through which degassed aerated water is injected into the aquifer and a pumping well through which water, partly free of iron or manganese, is abstracted. A typical Nitredox plant comprises a number of injection-pumping wells located on the circumference of two concentric circles and a pumping well in the centre through which water, partly free of nitrates and iron and/or manganese, is produced. Water with the carbon nutrient is injected through the wells located on the outer circle, while the wells located on the inner circle play the role of the Vyredox injection wells. The Nitredox process is associated with the formation of nitrogen, which is removed through the wells located on the inner circle. Vyredox and Nitredox processes include flow phenomena, transport, chemical reactions and bacteriological processes. These phenomena are described and formulated mathematically as a first step in the mathematical modelling of such processes.