Laboratory experiments were carried out to
investigate the mechanisms of electrochemical disinfection
of artificial wastewater contaminated by
Escherichia coli
culture (5 × 10
5 UFC/100 mL) using electrocoagulation.
In order to go deeply into the mechanism of the process, the
behaviors of two dissolved-type electrodes (ordinary steel
and aluminum) and a non-dissolved-type (carbon graphite)
electrode were compared. The ordinary steel electrode was
found more efficient for
E. coli cells destruction compared
to aluminum and carbon graphite electrodes. In order to
determine the most favorable condition for the treatment,
the effect of various supporting electrolytes including,
sodium chloride, sodium sulfate and sodium nitrate, was
scrutinized.
E. coli is inactivated by 5 log units for a charge
loading of 37.30 F/m
3 for sodium sulfate, 24.87 F/m
3 for
sodium nitrate and 12.43 F/m
3 for sodium chloride. It thus
appears that the most favorable supporting electrolyte type
for this method of disinfection is sodium chloride, a fact
which can be explained by the formation of disinfectant byproducts
such as chlorine dioxide, hypochlorite ions and
perchlorate ions. From the results obtained, electrocoagulation
applied to the elimination of
E. coli proceeds through
three combined effects: the electric field, the actions of
oxidants electrogenerated during the process and the
adsorption by the metallic hydroxides formed in solution.
