A mercury remediation method and apparatus for reducing mercury levels in water to a nanogram per liter level that uses four treatment steps: (1) chelation; (2) oxidation; (3) reduction; and (4) air stripping, vapor/liquid separation. There is a fifth step in the process, which does not involve the wastewater. It is to scrub the stripper air of the volatile mercury in an off-gas adsorption unit or to condense volatile mercury in a cryogenic mercury trap.