The present invention relates to a process for working up organic secondary components which are formed in the one-stage or two-stage nitration of toluene to dinitrotoluene. These organic secondary components are present in the acidic and alkaline waste water from the dinitrotoluene washing step and in the aqueous distillate from the sulfuric acid concentration step, together with small amounts of mononitrotoluene and dinitrotoluene. This process comprises

• a) combining the acidic and alkaline waste waters from the washing step and the aqueous distillate from the sulfuric acid concentration step such that the resulting mixture has a pH below 5,
• b) separating the aqueous and organic phases which form by phase separation, and
• c) recycling the organic phase from step b) into the nitration process.