A wastewater treatment process by an electrochemical apparatus, said apparatus having at least an electrochemical electrode (30), and said electrochemical electrode (30) having suitable electrode plates comprises the following steps: passing high concentration wastewater containing undesirable solutes through at least one electrochemical electrode (30) to which a DC electrical current is applied to destroy the undesirable solutes in the water intake, so as to output water having a lower concentration of the undesirable solutes; the DC current applied to the electrochemical electrode (30) comprises at least a constant potential difference stage exerted on both ends of the electrochemical electrode (30), and followed by a constant current stage through the electrochemical electrode (30).