Sewage is known to contain varying levels of pharmaceutical and personal care products (PPCPs), but waste water treatment approaches are able to remove the chemicals and their metabolites effectively, according to a study scheduled for publication in the Journal of Environmental Monitoring.
PPCPs have been detected in the UK river system, but until know no study has attempted to work out the contribution that sewage makes to this burden. The encouraging finding from this study is that treatment approaches such as activate sludge processing (ASP) are able to cope with the chemicals; however, it also uncovered stark differences between sewage treatment works in the efficiency of their removal.
The research team, led by Rakesh Kanda of independent environmental research consultancy WRc-NSF , investigated a number of analytical approaches to monitoring PPCPs at six sewage treatment works in the UK.
Their work showed that PPCPs do occur in sewage influent but in most cases are removed by various wastewater treatment processes and sewage treatment works. PPCPs include a wide range of chemicals such as prescription drugs as well as diagnostic agents, fragrances, sunscreen agents, and various other compounds commonly present in household items (e.g. detergents, cleaners, toothpastes etc).
A number of PPCPs including painkillers (aspirin, ibuprofen), cholesterol control medication (clofibric acid), antibacterial agents (triclosan), musks (including galaxolide and tonalide), X-ray contrast media (diatrizoate), cancer treatment drugs (cyclophosphamide) and antidepressant drugs (fluvoxamine) were investigated in the study.
Samples were extracted using solid phase extraction or liquid-liquid extraction and the extracts analysed using capillary gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring or liquid chromatography mass spectrometry (LC-MS) or LC-MS-MS.
The results obtained show that aspirin, clofibric acid, diatrozate, fluvoxamine and cyclophosphamide were not detected in any of the crude sewage or sewage effluent samples above the limit of detection of the applied methods.
However, ibuprofen was detected in all crude sewage samples as well as in all effluent samples with one exception, namely a treatment works which included a large hospital in its catchment area and used a broad range of treatment technologies, including various types of ASP. Removal of ibuprofen by the different sewage treatment works was generally between 80-100 per cent, with the exception of one facility where removal was poor (14.4 to 44 percent).
The antimicrobial triclosan, which is now appearing in a huge range of personal care items and even kitchenware, was also detected in all crude sewage samples and in all sewage effluent samples. A high removal efficiency (95.6 per cent) was observed in effluent samples, although one site covering a domestic catchment area was less efficient, indicating that the antibacterial may be entering the environment via this route. There are concerns that the presence of triclosan in the environment may engender bacterial resistance to the agent.
The researchers conclude that analyses are able to determine the efficiency of PPCP removal in sewage and could be used to ensure that sewage treatment works use the best available technology to strip out these chemicals.