3. Defects and shortcomings of conventional treatment

The treatment described above enables the emission limit values imposed for most effluents to be met, provided that each stage has been carried out correctly.

• The difficulties encountered are mainly due to :

  • insufficient contact times in the reaction vessels and/or decanter, with incomplete reactions and imperfect decanting;

  • the presence of stable or very stable metal complexes, precipitation being only partial or impossible;

  • incorrect pH and potential settings, or electrode maintenance faults (incorrect calibration or insufficient cleaning).

• The treatment is complex and very costly in terms of investment and operation, as it requires :

  ...