Abstract: A redox water treatment method comprises first determining the composition of water and whether water treatment requires either oxidation or redaction, or both to optimize nitrogen removal by a bioreactor. Sulfur dioxide (SO2) is injected into the water to he treated to provide H+, SO2, SO3=, HS03?, dithionous acid (H2S2O4), and other sulfur intermediate reduction products forming a sulfur dioxide treated water, which behaves either as a reducing agent or an oxidizing agent depending on the strength of the acid concentration, which alters sulfurous acid from a reducing agent to a more powerful oxidizing agent.