A waste stream is treated in a pre-filter having media, preferably sand, connected below a zero-valent metal column reactor incorporating a metal with reducing potential, preferably elemental iron (Fe.sup.0); the combination preferably configured as a single unit. The waste stream is pumped through the pre-filter to trap solids and deoxygenate it, then enters the reactor and is subjected to a reducing process. Most of the Fe.sup.0 is transformed to the ferrous ion (Fe.sup.+2), mixed with the reduced product, and fed to a continuous stirred tank reactor (CSTR) in which Fenton oxidation occurs. The output is then sent to a sedimentation tank and pH-neutralized using a strong base such as sodium hydroxide (NaOH). The aqueous portion is drawn off and the sludge pumped from the sedimentation tank. The system is monitored and controlled to optimize required additives, while monitoring of pressure drop across the pre-filter and column reactor establishes replacement requirements.