Linear alkylbenzene sulphonates (LAS)
and nonylphenol polyethoxylates
(NPnEO, n = 1- 20) are widely used
anionic and nonionic synthetic
aromatic surfactants. LAS is predomi nantly contained in laundry detergents,
whereas NPnEO are mostly employed
for industrial and institutional cleaning
and various other industrial purposes.
Commercial LAS and NPnEO are
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characteristically complex mixtures of
many isomers, homologs, and oligo mers. These aromatic surfactants are
mainly used directly in water, dis charged into municipal and industrial
wastewaters and subsequently released
to sewage treatment plants (STP's).
Unaltered LAS and nonylphenol (NP),
the latter being a highly toxic de-ethox ylation intermediate of NPnEO biodeg radation [1], occur in digested sewage
sludges at average levels of 5 and 1 g
kg- 1 [w/w, dry weight (d.w.)], respec tively [2-4]