Selenium removal using aluminum salt at conditioning and reaction stages to activate zero-valent iron (ZVI) in pironox process

A system comprising:

• a reactor vessel including zero valent iron media at least partially coated with an iron oxide compound disposed within the reactor vessel;
• a source of a conditioning additive comprising a soluble aluminum salt in fluid communication with the reactor vessel and configured to introduce the conditioning additive into the reactor vessel to contact the zero valent iron media and produce a conditioned zero valent iron media;
• a source of contaminated water fluidly connectable to the reactor vessel and configured to introduce the contaminated water into the reactor vessel to contact the conditioned zero valent iron media;
• a source of a reaction additive comprising a soluble aluminum salt in fluid communication with the reactor vessel and configured to introduce the reaction additive into the reactor vessel to contact the contaminated water and conditioned zero valent iron media;
• and
• a process control subsystem configured to maintain a concentration of aluminum ions within the reactor vessel within a predetermined range,
• the process control subsystem further comprising:
• a first sensor system configured to measure at least one of a flowrate of a solution being received in the reactor vessel through the at least one inlet and a concentration of one or both of the conditioning additive and the reaction additive;
• and
• a second sensor system configured to measure a concentration of one or both of the conditioning additive and the reaction additive in the solution within the reactor vessel,
• the control module being in electrical communication with the first and second sensor systems and configured to receive information from the first and second sensor systems.