Biodegradability and Treatability of
Alkylphenol Ethoxylates —
A Class of Nonionic Surfactants
EDWARD S.   LASHEN,   Senior Microbiologist
KEITH A. BOOMAN, Laboratory Head
Surfactant Applications Laboratory
Rohm and Haas Company
Spring House,  Pennsylvania
INTRODUCTION
A serious detergent pollution problem was averted as a result of the detergent industry's switchover to the manufacture of biodegradable surfactants. Linear
alkylate sulfonate (LAS), the principle type of anionic surfactant now in widespread use, was found to be much more biodegradable in laboratory and field tests
than its predecessor ABS (1, 2, 3,4, 5, 6). Since the switchover from ABS to LAS,
evidence reaffirming the extensive degradability of LAS is being documented continuously (1).
Now concern exists for the biodegradability and treatability of another major
class, the nonionic surfactants derived in part at least from ethylene oxide. Industrial and household nonionic surfactant consumption is considerable (roughly
one-fifth of the total). In view of this high usage, the current lack of foaming in
our waterways and treatment plants strongly suggests high biodegradability and
treatability of nonionics, implying that this class of surfactants does not present a
pollution problem. Nevertheless, industry is cooperating with governmental regulatory agencies and universities in continuing research efforts to evaluate the
biodegradability of these compounds.
The  common nonionic surfactants are synthesized from alcohols or alkyl-
Ehenols. Ethylene oxide nonionics based on linear primary or secondary alcohols
ave been shown to be degradable and treatable (7, 8, 9,10,11). The biodegradability of the ethoxylates of alkylphenols, of proven utility in many cleaning operations, has been studied in depth during the last three years in the laboratories
of the Rohm and Haas Company. We have reported high degradability of one type
of alkylphenol ethoxylate, the 10-mole ethoxylate of p, t-octylphenol (OPE^o),
in activated sludge, river water die-away and septic tank laboratory test systems
(10,12,13,14). In a recent field study, Lashen and Lamb (15) have shown this
surfactant to be biodegradable and treatable in a full-scale sewage treatment plant.
The purpose of this paper is to assemble in a comprehensive manner the results of our studies on the biodegradation of OPEio (p, t-octylphenoxynonaethoxy-
ethanol), and to demonstrate the importance of the acclimation processes in evaluations of alkylphenol ethoxylate biodegradability. The OPEi q used in the studies
was commercial Triton X-100, manufactured by Rohm and Haas Company, Philadelphia, Pennsylvania. The chemical structure of the OPE10 molecule is shown
in Figure 1.
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