Abstract: The present invention provides an integrated method and system for treating a contaminated fluid. The integrated system and method is configured to simultaneously perform multiple functions, for example, transportation, mixing, treatment and separation. The contaminated fluid and treating agents are pumped simultaneously into a processing tank and vigorously mixed by at least one pump-mixer. The at least one pump-mixer is configured to simultaneously perform combined functions such as fluid transportation, rapid and vigorous mixing and treatment. The rapid and vigorous mixing by at least one pump-mixer enhances the processing rates considerably. The contaminants and the disaggregated particles undergo treatment as a result of their reactions with the treating agents. The process residuals, usually in the form of sludge, are separated from the treated fluid. The separation system is also configured to simultaneously perform multiple functions.