A system and method for remediation of polluted sites, implementing a combination of chemical and biological breakdown modes on the contaminating compounds. The system includes at least one reactor for production in situ of reagents required for the breakdown modes. The reactor includes at least three types of substantially independent electro-cells for production of Fenton reagents and dissolved oxygen. The method according to the invention includes utilizing at least one reactor which comprised of substantially independent electro-cells for producing reagents required for remediation of the polluted sites and a computerized controller loaded with data obtained from a site survey, measurements made by instruments and programmed sequence.;The existing remediation techniques encounter in serious difficulties due to poor process control. Using the system according to the present invention allows control of the parameters and acceleration of the remediation process.