The environmental fate of the primary degradation products of alkylphenol ethoxylate surfactants in recycled paper sludge

Alkylphenol ethoxylates (APEOs) are a group of non-ionic surfactants that a re degraded microbially into more lipophilic degradation products with estr ogenic potential, including nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), octylphenol (4-tOP) and nonylphenol (4-NP). Nonylphe nol ethoxylates are used in paper recycling plants for de-inking paper and have the potential to be released into the environment through spreading of wastewater treatment sludge for soil amendment. Three samples of recycled paper sludge were collected from farmers' fields and analyzed for concentra tions of NP1EO, NP2EO, 4-NP and 4-tOP. Each sample differed in the amount o f time elapsed since the sludge was placed on farmers' fields. Primary degr adation products of APEOs were present at low mu g/g concentrations in the sludge samples. Differences in the concentrations of these analytes in slud ge samples indicated that APEO concentrations declined by 84% over a period of 14 weeks on farmers' fields. Changes in the chromatographic patterns of acetylated 4-NP indicated that there is a group of recalcitrant nonylpheno l isomers that degrades more slowly than other isomers. These data indicate that microbial degradation may reduce the risk of environmental contaminat ion by these compounds, but more work is required to assess the toxic poten tial of APEOs in sludges used for soil amendment. (C) 1999 Elsevier Science Ltd. All rights reserved.