An apparatus for treating a fluid (F) containing biological pollutants by means of an electric field (E) comprises an alternating voltage generator (4) that applies in a continuous way an oscillating electric potential to a single electrode (5) connected to a first pole of the generator (4), the other pole remaining unconnected, and operatively insulated from conductive members having an electric potential different from its own, the generator (4) being adjustable at least as to the value and oscillation frequency of the oscillating electric potential applied to the only electrode (5). Through this method it is possible to generate in fluid (F) an electric field (E) such as to cause the irreversible electroporation of the micro-organism(s) to be removed from the fluid without the electrode (5) being crossed by current nor having to resort to high values of voltage applied in pulses, and the relevant apparatus is simpler, cheaper and more flexible in use.
