Occurrence and removal of emerging contaminants in wastewaters

SummaryThe research will develop and apply analytical methods to study the occurrence, fate and significance of two very different groups of chemicals for which there is growing evidence that they are likely to be present in the aquatic environment in amounts that are of concern. The first of these groups, the benzotriazoles, are utilised in industry, amongst other applications as anticorrosive agents, and in the home they fulfil the same function when formulated into dishwasher detergents. With greater ownership of dishwashers in the UK it is likely that discharge of these compounds to wastewater treatment works will increase. Evidence that concentrations in some European rivers are above safe levels would indicate that in the UK, where a significant proportion of flow to the rivers is from sewage effluent, a similar situation may exist.The second group of chemicals to be studied are the progestogens, which includes the natural hormone progesterone and a number of synthetic progesterones utilised in contraceptives and hormone replacement therapy. These compounds will certainly be present in wastewaters through excretion by those taking them and evidence from studies with estrogens would indicate that they will be removed to differing degrees by wastewater treatment processes and hence be discharged to the environment. It has been known for over three decades that hormonally-active micropollutants can, and sometimes do, adversely affect aquatic organisms, with one example being the feminisation of fish by estrogens. However, research on estrogenic micropollutants in the aquatic environment is now slowing, but the lessons to come from it are having considerable ramifications, and opening up many different avenues of research. If estrogens are present in the aquatic environment, why not synthetic progestogens? Natural progesterones play an important role in reproduction in fish, controlling maturation in both sexes and they also function as pheromones at extremely low concentrations. As synthetic progestogens are effective in humans, and are designed to resist degradation, their presence in effluents discharged to rivers is very likely, and probably the only real issue is at what concentration do synthetic progestogens cause adverse effects on aquatic organisms (particularly fish), and how different is this concentration to those in the aquatic environment.The outcome of the study will provide data on the concentrations of both of these groups of compounds in wastewaters and in particular will focus on their removal in both traditional wastewater treatment processes and selected advanced treatment processes. This is of significance as, at present our understanding and observational data indicates that the compounds are poorly removed in traditional wastewater treatment plants.. The significance of concentrations observed in receiving waters will be related to known data on effects and will inform regulators on the quality of the water bodies.