Enhancing micro-pollutants removal from hospital wastewater by biological design

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The release in natural waters of biologically active contaminants is a serious concern at a time when ever-increasing demand threatens water security. While many of these xenobiotic compounds have recognized ecotoxicological effects, there is a growing concern on their human toxicity too. Increasing ubiquity of micro-pollutants in natural waters opens the possibility of their presence in drinking water. Conventional drinking water treatments aim to remove pathogens, reduce turbidity and control odour and taste and the employed engineering processes reduce somewhat the load of micro-pollutants. Complete removal, however, involves high chemicals and energy demand technologies and therefore, in the current state of knowledge, theirpotential benefits are not worth the environmental expenditure.Waste water from hospitals is likely to have high concentrations of pharmaceutical substances and their degradation products but does not undergo any further waste water treatment before reaching the sewage. This is of concern as some micro-pollutants are not removed by the traditional water treatment methods, and may affect drinking water we consume. Working alongside NHS Highlands, it is proposed to investigate the use of a biotechnological pre-treatment for hospital wastewater.Treatment biotechnologies remove pathogens, nutrients and transition metals through a mixture ofphysical and biological processes. For instance, ammonia oxidizing bacteria (AOB) and ammoniaoxidizing archea (AOA) carry out transformation of ammonia via their ammonia monooxygenase(AMO) enzyme. Importantly, the AMO enzyme has broad substrate specificities and canalso oxidiseco-metabolically a wide range of contaminants. This property opens the possibility that the ammonia oxidising community of biological treatments can be optimisedto efficiently remove both nutrients and micro-pollutants. The aim of this project is to identify key nitrifying microbial communities and conditions to design an inncoulum for biological filters for untargeted biotransformation of contaminants alongside ammonia removal. Initial work will be to create microcosms from various environments including coastal and river sediments, nitrifying activated sludge and lab-scale biological filters under nitrifying conditions spiked with ammonia and environmentally relevant loads of micro-pollutants. Using novel analytical approaches, quantitative polymerase chain reaction and targeted gene high-throughput sequencing, the nitrifiers and their co-metabolic response to micropollutants present in hospital wastewater will be characterised. Based on these results, a nitrifying community with the capacity to also oxidise a broad range of micro-pollutants will be engineered. Through a new series of microcosms, further investigation into the removal rates of mixtures of contaminants at high concentrations by this seed community and their relationship to ammonia concentrations and other chemical parameters. Finally, quantitative structure-activity relationship modelling will be establish to predict degradation of untested pollutants and multiple regression analysis to recommend remedial approaches to failure (dosing of ammonia, change in pH...).