Reduction of
Foaming of ABS by Ozonation
C. A. BUESCHER, JR., Superintendent of Purification
Northern Illinois Water Corporation
Champaign, Illinois
and
D. W. RYCKMAN, Director
Environmental and Sanitary Engineering Laboratories
Washington University
St. Louis, Missouri
With the ending of World War II in 1945, materials which were required
for defense production were released for consumer use. Thus, the new era of
synthetic materials was unleashed upon the American market, Materials
which had been accepted as irreplaceable were suddenly being replaced. One
such product caught in this revolution was the familiar household item --
soap.
Soap had been used for years as the standard household cleaning agent.
Its main drawback, however, has been its ability to react with the hardness
causing cations in water. Thus, when synthetic detergents or syndets were
placed on the market with the promise that water hardness had no effect on
its detergent abilities, sales soared. In fact, syndets accounted for approximately 50 per cent of the detergent sales by the early 1950's (1). This figure
has now been estimated at 90 per cent of the home detergent sales (2).
Unfortunately, as in nearly all revolutions, the bitter comes with the
sweet. In 1947 (1) samples of a new synthetic detergent were distributed to
housewives in the town of Mount Penn, Pennsylvania, on a Friday afternoon.
By the following Monday morning, foam two to five ft deep had formed on the
aeration basin of the activated sludge plant. This incident has been reported
as the first instance of foaming which was directly caused by synthetic detergents. Since this time, sanitary engineers have been investigating syndets
to determine their effects on water and waste water, and to find methods of
treating them.
Modem day syndets are composed of surface active agents, complex
phosphate builders and allied products (2). The surface active agents or surfactants are the active portion of the syndet and constitute 20 to 35 per cent
of the syndet by weight. The surface active agents are classified according
to their ionization in water; thus, there are anionic, cationic and nonionic
surfactants.
Since the syndet field is highly competitive, the price of commercial
products is kept at a minimum by the use of surfactants which are readily
available and low in cost. The anionic surfactant has become the most popular because of its low cost. It has been estimated that the anionic surfactant
composes more than 80 per cent of the total surfactants sold, with the tertiary
alkyl benzene sulfonate being the most common.
Because of its resistance to biologicaldegradation, the tertiary alkyl benzene sulfonate, more commonly referred to as ABS, is not removed by the
present methods of sewage treatment.    In addition,  surfactants have been
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