University of Bath

Fate of emerging contaminants in the UK: Mapping out the kinetics of degradation

This project aims to determine and model the kinetics of degradation of a large library of pure and mixed ECs in both wastewater effluent and drinking water.

This project aims at determining and modelling the kinetics of degradation of a large library of pure and mixed ECs in both wastewater effluent and drinking water, essential to inform the future development and scale-up of advanced technologies for their effective control and support drinking water and wastewater treatment industries to respond more effectively to forthcoming EU legislation on levels of emission of ECs in wastewater and in drinking water. New advanced oxidation technologies such as ozonation are now being adopted at large scale, however there is little information currently available in literature in respect to the rate of degradation of each EC. Also, little is understood at the moment in respect to the rate of removal of ECs by current biological treatment processes in waste water treatment plants.

Project outline

This PhD project will review the current state-of-the-art on the occurrence of ECs in wastewaters and surface waters in UK. Since the presence of ECs in the environment is mainly attributed to the discharge of treated wastewater from WWTPs, this review will focus on the ECs that are not removed by conventional secondary processes in WWTP resulting in their discharge to receiving surface waters. In particular, based on the level of knowledge and concern, the current study will take in account a certain number of ECs selected from a database of > 80 contaminants generated with CIP 2 project shared with industrial partner Severn Trent Water. These emerging substances will be analysed in respect to the (i) source, (ii) fate, (iii) concentration in WWTP influent and effluent, (iv) modelling kinetics of photocatalytic and biological removal treatment, (v) mass balance during the treatment plan, (vi) removal efficiency in WWTP by conventional biological treatment and advanced treatment processes and (vii) toxicological effects of ECs on human health and environment. Moreover the literature review will focus on (viii) ozonation as a mature advanced oxidation process and (ix) biological treatment processes. The literature review of this PhD will identify the key knowledge gaps that will provide the focus for subsequent work identifying the best methods that permit a good measurement of ECs at low concentration.

Science

The two main options that will be taken in account to reduce the concentration of ECs in WWTPs effluents are: (a) improvement and optimization of the existing treatment technologies and (b) addition of complementary advanced treatments. For those substances that require advanced treatments, conducted by the main supervisor, Dr Reis and collaborator Professor Li Puma (Loughborough University), AOP technologies will be applied. This PhD project will focus on the development of an efficient reactor and the modelling of involved chemical-physical phenomena in order to spread a sustainable use of AOP technologies for water and wastewater treatment. Therefore, the present research will be focused on the development of an innovative micro-photoreactor, which will be applied in the removal of several selected emerging contaminants. Moreover, a further novel approach for the intensification of ozonation of water and wastewater using a highly efficient and compact Multi-Orifice Oscillatory Baffled Column (MOBC) ozonation contactor will be applied to study the reduction of ECs. In detail, the experimental activity will be characterized by: (i) selection of a pool of target compounds and development of analytical methods for their measurement by laboratory instruments (using analytical facility at Professor’s Barbara Kasprzyk-Horder’s group based in the department of Chemistry), (ii) definition of reactor setup and commissioning (including detailed design and preliminary tuning), (iii) preparation of the aqueous matrix to be treated, (vi) management of advanced oxidation process, (v) reactor sampling and (vi) effluent analysis. Data will be processed for the assessment of reaction kinetics and process parameter impact on degradation yields. In particular, kinetic models reported in literature for the description of the advanced oxidation of refractory pollutants will be applied to experimental dataset, so as to highlight the model resulting in the best fitting and to estimate kinetic model parameters as a function of operating conditions.

Computational Fluid Dynamics (CFD) modelling of photolysis degradation of emergent contaminants in microfluidic systems and strategies for scaling- up will be studied intended for providing an reliable and easily reproducible methodology for the description of involved physical-chemical mechanisms. Therefore, an multi-physics system will be simulated: (a) radiation transfer equation will be solved in the reactor volume by means of numerical tools for defining the amount of photons provided to the system, (b) fluid dynamics will be assessed for understanding the reactor behaviour, (c) optics and fluid dynamics will be integrated with the kinetic model, taking advantage of the already-estimated kinetic parameters, so as to effectively reproduce the degradation of target pollutants in the micro-photoreactor under various operating conditions.

Impact

This PhD project aims at supporting the modernisation of both WTPs and WWTPs in respect to ability to remove ECs and the development of a full water cycle and more effective sustainable water-resource management. This project is supervised by Dr Nuno Reis and Dr Ana Lanham.