ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 9, pp. 1604 !1605. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + V.V. Marakov, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 9, pp. 1571!1572.
Electromagnetic Method for Softening Natural Water
V. V. Marakov
Berezniki Branch, Perm State Technical University, State Educational Institution
for Higher Professional Education, Berezniki, Perm krai, Russia
Received: October 9, 2006; in final form, March 2007
Abstract-A water softening method was saggested. The optimal parameters of the external electric field
were determined and apparatus for the implementation of the suggested method was described. The mech-
anism of the coagulation of hardness salts was studied.
The hardness determined by the concentration of
dissolved calcium and magnesium salts is one of im-
portant quantitative characteristics of quality of na-
tural water. Thermal, chemical, and ion-exchange
methods are used for water softening, i.e., for removal
of hardness salts from it . The thermal method of
water softening does not remove magnesium salts and
converts a half of dissolved calcium salts into in-
soluble compounds. The chemical and ion-exchange
methods involve ion-exchange processes to substitute
cations of dissolved calcium and magnesium salts by
the cations of chemical reagents used for water soften-
ing. The above methods of water softening lead to
secondary chemical contamination of water.
The known methods of electromagnetic softening
do not provide the necessary technical result and
require considerable energy expenditure per unit
volume of treated water.
A softening method involving treatment of water
with a pulsed electric field was developed . In this
method the energy expenditure per unit volume of
treated water is minimal, with no chemical contamina-
tion of water.
In this study, the optimal parameters of the external
electric field ensuring the necessary degree of soften-
ing of natural water were determined.
It was found that the exposure of water, irrespec-
tive of its volume, to a low-frequency electric field
causes hardness salts to convert into insoluble com-
pounds which form a precipitate containing 75% cal-
cium salts and 25% magnesium salts on the average.
The necessary degree of water softening is obtained
at a frequency of ac electric field varying from 1 to
5 Hz, intensity of the external electric field in the
treatment zone of 232.5 units, and a treatment time
of 10315 s. As a result of this exposure, the hardness
of natural water is half as large on the average. The
second stage of the treatment performed under the
same conditions (i.e., time and parameters of the ex-
ternal electric field are the same) causes the content of
calcium and magnesium salts to decrease by 25% of
their initial content on the average. The necessary con-
tent of hardness salts is obtained after multistage
treatment. The choice of the parameters of the external
electric field is determined by the technical result.
When treatment is performed at a frequency of less
than 0.5 Hz or more than 5 Hz, the hardness of natural
water decreases by 10% on the average and the chemi-
cal contamination of water owing to the electrolysis
takes place. The water softening method that we de-
veloped provides water treatment in both closed- and
The developed method uses two flow-through elec-
trolytic cells connected in series to decrease the
energy expenditure per unit volume of treated water.
Each cell has alternating ground and feeding elec-
trodes. The number of the electrodes in the cells is
determined by a water flow (average flow velocity in
the interelectrode space v < 0.1 m s
). This value of
the flow velocity provides the necessary technical
result on water softening. To the feeding electrodes of
each cell, connected in a series, ac electric field with
a frequency varying from 1 to 5 Hz was applied from
The voltage diagram measured across the resistor
(R = 5.86 W) connected in a series with the cell and
used for the determination of the current strength
passed through the treatment circuit was obtained for
the natural water treated in a 13.5 cm
cell by ac elec-