Treatment of Laundromat Wastes
I. Winfair Water Reclamation System
DONALD B. AULENBACH, Associate Professor
PATRICK C. TOWN, Graduate Assistant
MARTHA CHILSON, Graduate Assistant
Division of Environmental Engineering
Rensselaer Polytechnic Institute
Troy, New York
INTRODUCTION
Wastes from both individual home laundries and multiple-unit coin-operated
laundromats can present problems where they cannot be discharged into sewerage
systems provided with adequate treatment facilities. The spread of population into
unsewered areas is followed by the establishment of coin-operated laundromats in
these unsewered areas. An indication of the magnitude of the problem may be given
by the estimate that there are over 120 laundromats in Suffolk County, Long Island,
New York, alone (1). A summary of the amounts of wastes produced is shown in
Table I, and representative quality parameters are shown in Table II. Nearly all of
these ultimately discharge their effluent into the ground. The switch to the use of
synthetic detergents (syndets) has also contributed considerably to the problem. The
conversion to linear alkyl benzene sulfonates (LAS) (Table III) has reduced this
problem where aerobic biological treatment is provided. However, under anaerobic
conditions, such as in septic tanks and saturated soil, there is little breakdown of the
LAS. In saturated soils, these syndets may travel considerable distances without
being decomposed, thereby entering water supplies. In addition, studies on Long
Island (2) have shown that the synthetic detergents seem to cause other pollutional
material, specifically coliforms, to be carried greater distances than conventional
soaps do. This is in partial disagreement with work done by Robeck, et al. (3) who
showed that increased concentrations of ABS had no effect upon the travel distance
of coliforms in water-saturated, sandy soils under laboratory conditions.
The problems created by laundromat wastes have led to many studies of
methods for treatment, and to the creation of numerous waste treatment systems. A
large volume of work was done at Manhattan College for the State of New York (4).
Work was done to determine the amount of alum needed to improve the quality of
the waste (with no consideration of ABS removal), and further, the amount of
powdered activated carbon needed to remove the ABS. An alum dose of 100 grains/
gal (1700 mg/1) and an activated carbon concentration seven times the ABS concentration are recommended to remove substantially all anionic syndets. Close scrutiny
of the data reveals that the optimum conditions for clarification of the waste without
regard to ABS removal are 1530 mg/1 of alum at pH 5.7, with the ranges being 850 —
2210 mg/1 alum and pH 5.1 - 6.0. A dose of 1360 mg/1 of alum and 340 mg/1
powdered activated carbon at pH 6.0 produced an effluent containing 1.8 mg/1 ABS.
No studies were made to determine the removal of ABS by alum alone.
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