Endocrine disrupting chemicals are discharged into the environment
mainly through wastewater treatment processes. There is a need for
better understanding of the fate of these compounds in the unit
processes of treatment plant to optimize their removal. The fate of
oestrone, 17β-estradiol, 17α-ethinyestradiol and nonylphenol
in the unit processes of full scale wastewater treatment plants in the
UK, including activated sludge plant, oxidation ditch, biofilter and
rotating biological contractor were investigated. The overall removal
efficiencies of all the compounds ranged from 41 % to 100 %. The
removals were predominantly during the secondary biological treatment
with the rates of removal related to the nitrification rates and the
sludge age. The removal efficiency of the treatment processes were in
the order activated sludge > oxidation ditch > biofilter >
rotating biological contractors. Activated sludge plant configured for
biological nutrient removal showed better removal of the endocrine
disrupting chemicals compared to conventional activated sludge plant
effluents. Tertiary treatment was also significant in the removal
process through solids removal. Overall mechanisms of removal were
biodegradation and sorption unto sludge biomass. Phytoremediation was
also significant in the removal processes. The endocrine disrupting
chemicals persisted in the anaerobic sludge digestion process with
percentage removals ranging fro 10-48 %. Sorption of the endocrine
disrupting chemicals onto the sludge increased with increasing values
for the partitioning coefficients and the organic carbon contents of
the sludge
