1070-4272/01/7403-0449$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 3, 2001, pp. 449! 454. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 3,
2001, pp. 439!444.
Original Russian Text Copyright + 2001 by Konovalova, Stepanova, Vasilevskii, Bereza.
OF CHEMISTRY AND TECHNOLOGY
Intensification of the Flotation Treatment of Water
with Natural Polyelectrolytes
I. N. Konovalova, N. V. Stepanova, P. B. Vasilevskii, and I. G. Bereza
Murmansk State Technical University, Murmansk, Russia
Received August 24, 2000
Abstract-The influence of natural polyelectrolytes, sodium alginate and chitosan, on the efficiency of water
treatment by flotation to remove fish oil was elucidated by studying the kinetics of formation of adsorption
layers at the aqueous polyelectrolyte solution3air and aqueous polyelectrolyte solution3fish oil interfaces.
The stability of fish oil emulsions stabilized by sodium alginate and chitosan was studied.
Removal of fatty substances from water and aque-
ous solutions has become an especially urgent prob-
lem . Fat-containing wastewater is not appropriate
for biological and other water treatment works be-
cause fat impurities depositing on pipeline walls pre-
vent transportation of wastewater and disturb opera-
tion of the water treatment works. Fat removed from
wastewater can find use as a valuable supplement to
mixed feed for domestic animals and poultry.
The biopolymers studied in this work, sodium al-
ginate ANa and chitosan, are not toxic and exhibit a
set of properties making them suitable for removal of
fat and protein substances from wastewater generated
by food industry enterprises with their subsequent uti-
lization as food supplement .
Wastewaters generated at fish enterprises are com-
plex disperse systems whose main components are fat
and protein. Fat occurs in wastewater as emulsions
Coarsely dispersed systems are treated, in partic-
ular, by flotation and settling; finer emulsions are
broken down by coagulation, flocculation, and chem-
ical and biological methods. Additives of natural
polyelectrolytes such as ANa and chitosan can be used
for intensifying the flotation treatment of water, as
they can affect the stability of fat droplets and air
bubbles and their hydrophobic and hydrophilic prop-
erties. The suitability of ANa and chitosan as floccu-
lants in wastewater treatment was pointed out in a
number of publications [2, 5, 7311]. However, in
Russia these polymers have not as yet found wide
application because of their relative expensiveness .
Recently, a fairly inexpensive electrochemical method
of preparing polyelectrolytes of diverse nature from
hydrobiontics has been developed .
ginate and chitosan prepared by this method have low
prime cost and are suitable for development of waste-
free technologies and closed water circuits, e.g., in
production of hydrolyzates, isolates, and concentrates
The aim of this work was to elucidate how natural
polyelectrolytes ANa and chitosan affect the effi-
ciency of the flotation treatment of water to remove
We used ANa and chitosan with molecular weights
of 13 000 and 14000, respectively.
As fat addi-
tives served food-grade fish oil [GOST (State Stand-
ard) 3714372]. We prepared aqueous solutions of
ANa with concentrations ranging from 0.000025 to
0.25 g l
. Chitosan solutions of the same concentra-
tions were prepared in 1% acetic acid. The acidity of
the medium was adjusted using 0.1 M HCl and 0.1 M
NaOH. The pH value was measured with an I-135
pH-meter. The kinetics of formation of the adsorption
layers at the water3air and water3fish oil interfaces
were monitored by variation of the surface tension of
the solution s at the interface with time t. The surface
tension of the solutions was determined by the Wil-
helmi’s method . The half-relaxation time was cal-
culated by the procedure described in . The fish
oil3water emulsions were prepared using a PT-2 tissue
microcrusher (rotation rate 20 rps, stirring time 15 s),
and the content of ANa and chitosan additives in the
aqueous phase was varied within 0.231gl
Protein Joint-Stock Company, Murmansk.