Potable and non-potable water recycling from wastewater has become a key element of water infrastructure, particularly in regions where urbanisation, industrialisation, and climate change are placing considerable stress on the hydrological cycle. Pressure-driven membrane processes such as reverse osmosis (RO) are central to advanced wastewater treatment schemes, given their high removal of colloidal and dissolved contaminants. In Scotland alone, 45% of the water treatment infrastructure is underpinned by membrane processes. Nonetheless, state-of-the-art RO membranes do not achieve sufficient removal of small (molecular weight < 150 Da) neutral molecules. Among this class of compounds, nitrosamines such as N-nitrosodimethylamine (NDMA), a by-product of chlorination of wastewater effluent, is significantly concerning due to its carcinogenicity and genotoxicity. Removal of NDMA and other nitrosamines thus requires post-treatment and conversion to less hazardous end-products. Among post-treatment processes, UV photolysis is effective in degrading nitrosamines to less harmful amines, but involves high energy costs, while advanced oxidation by ozone or H2O2 is inefficient due to scavenging of hydroxyl radicals by natural organic matter and bicarbonate ions.
Reductive post-treatment has emerged as an alternative strategy for remediation, with catalysts such as Pd and Ru exhibiting extremely high activity for the H2 reduction of N-nitrosamines to ammonia and secondary amines, both of which are much less harmful compounds. Notwithstanding their high activity and stability, Pd and Ru-catalysed remediation still involves a separate unit operation downstream of the RO stage, requiring disposal of reduction products, and continuous H2 dosage to observe quantitative nitrosamine removal. If Ru/Pd catalytic NPs could be integrated into the RO membrane material, it would eliminate the requirement of costly post-treatment of the RO permeate (see scheme). Moreover, use of a membrane process would decrease the dose of H2 that would otherwise be needed for nitrosamine reduction, as the boundary layer formed near the membrane surface would yield a locally high concentration of contaminants and chemisorbed H2, thereby speeding reaction kinetics. Finally, a membrane process would decrease the concentration of reaction end-products in the treated water. This PhD studentship will demonstrate, for the first time, the integration of hydrogenation-metal-based catalytic NPs into polyamide RO membranes for the physicochemical removal of nitrosamines and other micropollutants.
Applications Deadline: Thursday 10 January 2019, 12pm.
Dr Efthalia Chatzisymeon; Dr Andrea Semiao
Minimum entry qualification - an Honours degree at 2:1 or above (or International equivalent), possibly supported by an MSc Degree, chemical engineering, environmental engineering, or cognate fields such as materials science or chemistry. Previous research experience in materials synthesis is highly desirable.
Further information on English language requirements for EU/Overseas applicants.
This project is funded by NERC (UKRI) and as such, is regulated by the Terms and Conditions of Research Council Training Grants.
To be eligible to apply for a fully-funded DTP studentship, applicants must:
- be a UK or EU citizen or a non-EU citizen with permanent settled status in the UK (known as ‘indefinite leave to remain’)
- have been ordinarily resident in the UK for at least 3 years prior to the start of the studentship (this applies to all citizen categories).
Fees Only Award
EU citizens who will not have lived in the UK for the last 3 years preceding the start of the studentship would normally be eligible for a Fees Only Award. Fees Only Awards only cover fees and research costs. They do not include stipend. Therefore, funding to cover living costs for at least 3 years will need to be sought from another source.