Abstract:
Endocrine disrupting chemicals such as steroid estrogens and alkylphenol
polyethoxylates entering the environment via regular domestic or industrial discharges
have been demonstrated to cause feminization of aquatic organisms at trace levels.
Despite these discharges, the solid-end product of wastewater treatment i.e. digested
sludge, poses a potential source of these compounds in the environment when sewage
sludge is recycled onto land. Greater concentrations of alkylphenolic metabolites such
as alkylphenols and short-chained one to three ethoxy units, ethoxylates have been
reported to occur in digested sludge than the parent compounds.
This study investigates the fate and behaviour of these chemicals in mesophilic and
thermophilic anaerobic digestion by using primary sludge and a mixture of primary and
secondary sewage sludges. The analytical methodologies used for the determination of
these endocrine disrupting compounds allowed accurate quantification at microgram per
kilo of dry-sludge weight concentrations in the complex sludge matrices. Four
mesophilic and two thermophilic semi-continuous lab-scale anaerobic digesters were
examined. In addition, acclimated sludges were dosed with high nonylphenolic
concentrations to observe the capacity of biomass to remove these compounds. Cont/d.
