REMOVAL OF ENDOCRINE DISRUPTING CHEMICALS BY TRICKLING FILTER PROCESS – ESTROGENICITY OF THE TREATED EFFLUENT
Caroline Xun Huo* and Paul Hickey
MWH
(free)
The environmental impact of endocrine disrupting chemicals (EDC) has been intensively researched
over the last 10 years. One of the observations highlighted has been the relationship between
feminization of male fish (known as intersex) and the discharge of steroid estrogens from sewage
treatment works (STWs). Compounds that act like estrogens found in certain industrial chemicals have
also been blamed for such effect. Given the long-term effect this may have on fish population, it is
anticipated that EDC removal may be imposed in the future discharge consent to ensure the
concentration not exceeding a Predicted No Effect Concentration (PNEC), taking into account of the
dilution capacity in the receiving water.
Currently, there is a lack of understanding as to how the steroid estrogens and other EDCs are
removed through various wastewater treatment processes. The information in the literature is often
based on very few analyses, therefore not statistically representative. To address this information gap
and ensure that future policy decisions are well founded, the Environment Agency (EA) and
Department for Environment, Food and Rural Affairs (Defra) have instigated a Demonstration
Programme, which involves collecting baseline data at 17 STWs across the UK and removing EDCs at
2 STWs using full-scale advanced treatment. This paper focuses on the baseline data element of the
Demonstration Programme.
Being the first company to pilot the Demonstration Programme, Anglian Water has developed a
validated method for estrogen analysis, together with an effective preservation technique. To date,
Anglian Water has completed its own sampling programme. The data collected has been shared with
other water companies and used by the steering group to refine the remaining programme
The initial results from a trickling filter site demonstrated that in the treated effluent, the average total
estrogen concentration (as E2 equivalent) measured by chemical analysis was 17 ng/L; the
estrogenicity (as E2 equivalent) measured by YES bioassay was 4 ng/L. Therefore, taking into
account the river dilution capacity (in this case, dilution ratio is 5), a trickling filter process on its own is
unlikely to meet the proposed PNEC of 1 ng/L in the receiving river based on chemical analysis but
may achieve it according to YES bioassay. Therefore, the EA has to take a view on this in the
proposed consent standard. The removal rates for 3 estrogens were: 76% for E1, 90% for E2 and 8%
for EE2.
KEY WORDS
EDC, Demonstration Programme, Steroid estrogen analysis, YES bioassay, Trickling filter
