Papini, M.P., M. Majone, F. Arjmand, D. Silvestri, M. Sagliaschi, S. Sucato, E. Alesi, E. Barstch, and L. Pierro.
Chemical Engineering Transactions 49:91-96(2016)

A groundwater circulation well (GCW) is designed to create in situ vertical groundwater circulation cells by drawing groundwater from an aquifer through one screened section of a multi-screened well and discharging it through another screened section. The pressure gradient between the two hydraulically separated screen sections in the well induces a circulation flow in the aquifer, forcing water through less permeable layers and moving groundwater through the treatment zone both horizontally and vertically. Researchers tested the possibility of using a GCW to enhance in situ bioremediation in an operating industrial site affected by different chlorinated solvents (concentrations up to 100 mg/L) in a complex hydrogeological saturated zone. A GCW at 30 m depth with three screen sections was designed and installed at the site for pilot testing. Groundwater pumped toward two screen sections of the GCW was reinjected into the aquifer by another screen section after passing through an external unit treatment. The external treatment unit comprised a sand filter tank and two reactors: one filled with a biodegradable polymer (polyhydroxy-butyrrate, or PHB) and the other with a mixture of zero-valent iron and PHB. Results from the first 8 months of operation demonstrated how groundwater recirculation through the PHB reactor allowed continuous delivery of electron donors that enhanced contaminant mobilization and stimulated natural attenuation processes. http://www.aidic.it/cet/16/49/016.pdf