China: sewage plant study raises concerns

Many water treatment facilities in China are failing to remove toxic organic chemicals and levels of some chemicals are actually increasing during treatment, according to researchers from Nankai University, Tianjin.

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One of the chemicals monitored is nonylphenol, released during the breakdown of nonylphenol polyethoxylate detergents. Nonylphenol is an endocrine disrupter and, together with nonylphenol ethoxylates, is banned in the EU because of possible threats to human health.

[The researchers] found that the sewage treatment works only removed 60-70 per cent of nonylphenol polyethoxylate from water, while similar facilities in Europe and North America remove up to 90 per cent of the compound. To make matters worse, nonylphenol polyethoxylate degrades into smaller metabolites, such as nonylphenol, which could be 70 times more toxic than their precursors.

[The researchers] also discovered that [activated sludge] sewage treatment increased levels of the industrial surfactants perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) – persistent organic pollutants (POPs) that may have metabolic, reproductive and neural toxicity.

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Zhang Pengyi, director of the Institute of Environmental Chemistry of Beijing-based Tsinghua University, [commented that] “this should not indicate that sewage treatment plants are the source of the pollutants. PFOS and PFOA form through normal degradation processes of many chemicals in the common environment@.

Source: Hepeng Jia, Royal Society of Chemistry, 22 Aug 2008