| Chromium residues are the main environmental pollutants, they pollute water, soil and disserve the health of life-form. Therefore, a fast, sensitive determination method and a high-efficient treatment technology should be put forward. This has become a hotspot in the field of environmental protection. Author put forward a new method, namely, constant current coulomb / oscillo-potentiometric method. This method is convenient, fast, sensitive and exact. The alkaline waste water was treated with indirect electrolysis method in the same time. The result is satisfying.In constant current coulomb/ oscillo-potentiometric method, end point was indicated through zero current oscillo-potentiometric method. For the two indicating electrodes have different rate of reaching balance, end point can be confirmed through the sudden displacement of fluorescence point. Because fluorescence point displacement has no inertia, it can respond the difference of the instantaneous potential between indicating electrodes sensitively. In this experiment, the electrolyte components were studied and properelectrolyte was confirmed: 3.5mol/LH2SO4+0.6mol/LH3PO4+0.015mol/L NH4Fe(SO4)2.The electrolyte were tested using cyclic voltammetry, and the results indicated that only the reaction Fe3+ +e —> Fe2+ occurred. The effect of surfactant and disturbances of co-exist ions were studied. The recycling efficiency is between 99%~101%, comparing with standard method, it has no obvious difference.It was proved that the method of electrolyzing and generating Fe2+ to deoxidize Cr(VI) in alkaline solution is feasible. Comparing with conventional method, this method is more economic. The effect of various factors were studied and appropriate electrolysis conditions were confirmed. The erode of electrodes were discussed and the changes of solution during the process of electrolysis were studied. Actual Cr(VI) waste water of 56.34 mg/L can be treated effectively in 45min. Therefore, the treating method is very simple and convenient.
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