Urban Waste Water

Behaviour of selected estrogen and xeno-estrogen in 'natural process' sewage plants

On average pond systems are less effective than biological sewage plants in eliminating endocrine substances. It has also been shown that long hydraulic retention times, high biomass concentration, effective biomass retention and an adequate oxygen supply have a positive effect on the retention/elimination of nonylphenol and bisphenol A.

Summary

In contrast to the activation pools and percolating filters, the sewage in ponds and biological treatment plants generally undergoes longer hydraulic retention.
The aim of the project was to investigate the effectiveness of pond and biological treatment plants (vertical filter) with regard to the retention or elimination of estrogen containing nonylphenol and bisphenol A. To achieve this, analytical methods were developed to show the effective estrogen content of complex sewage, and plant tests and pilot projects were initiated to reveal the elimination mechanisms in laboratory space reactors.

Results:

Low solvent extraction techniques were developed to reveal the endocrine substances in sewage. This provides optimum and validated testing methods for various concentration areas.
The tested pond treatment plants showed an average elimination rate for nonylphenol in untreated water of 58% compared with an average of 72% in biological plants. The average elimination rate for bisphenol A in both treatment plants was 82% , higher than the 68% rate for nonylphenol.
Tests showed that biological treatment plants with generally complete nitrification had higher elimination rates for nonylphenol and bisphenol A than systems with incomplete nitrification.
Laboratory experiments established that bisphenol A is eliminated in biological treatment plants under anaerobic conditions. The biomass absorbs large amounts of nonylphenol.

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Source: German National Library of Science and Technology Hannover (TIB)