The pollution of groundwater with arsenic through natural or anthropogenic processes, and the subsequent long-term exposure through drinking water, threatens human health on a global scale. Though serious risks are known to occur in developing countries such as Bangladesh, China and India, high blood concentrations have been found in the UK with the residents of Devon and Cornwall. Due to the severe health effects of arsenic (the most toxic element known to humans), most governments worldwide including the US and UK have recently lowered the admissible arsenic concentration in drinking water to 10 ng/ml. Achieving these new stringent threshold values poses real challenges to the water industry and current treatment devices struggle to meet these criteria. One of the foremost reasons for these failures is that the processes currently employed (namely adsorption on iron and activated aluminium oxide substrates) are adversely affected by the presence of small concentrations of phosphorous and silica in the waters, which in turn significantly diminish the performance and life span of the treatment plants. Here we suggest a novel approach based on a combination of two different sorbents, with different treatment tasks. The first stage is composed of a bi-composite synthesised of TiO2 and Fe2O3. This device has been designed to remove phosphorus and silica from the waters and to oxidise any arsenic(III) that might be present to arsenic(V) (i.e. arsenate). This pre-treated water then passes through a second stage, which is composed of an arsenic specific chemical receptor. This second treatment step will be based on metallo-receptors with high affinity for oxoanions such as arsenate. The ultimate outcome of the project is a novel low cost water treatment device using the technologies described above with a long live span that will remove arsenic from water below the levels currently considered to be unacceptable. In order to understand the mechanisms of the arsenic interaction with the bi-composite and the metallo-receptor, we will conduct extensive chemisorptive studies of the functionalised materials and determine the key factors that need optimising for efficient binding. This work will include spectroscopic investigation using various techniques such as synchrotron radiation and nuclear magnetic resonance. Our findings will also have fundamental implications on our understanding of the environmental chemistry of arsenic and oxyanions in groundwater.

The wastewater treatment process (WWTP) plays a critical role in providing clean water. However, emerging and predominately unregulated, bioactive chemicals such as steroids and pharmaceutical drugs are being increasingly detected in surface waters that receive wastewater effluent. Although present at low concentrations, their inherent bioactive nature has been linked to abnormalities in aquatic organisms and there are also water reuse and human health implications. As part of the urban water cycle, the WWTP is the gatekeeper to the surface waters e.g. rivers. Pharmaceuticals enter wastewater treatment from inappropriate disposal of unused drugs to the sink/toilet or via landfill. Prescribed or illicit drug use also has the inevitable consequence of being metabolised in the human body (to parent, Phase I / II metabolites) and excreted in urine, which subsequently enters the WWTP. Coupled with naturally produced and excreted bioactive steroids, the challenge for wastewater treatment is that it was never designed to remove these bioactive chemicals and is inefficient. Evaluating the prevalence and fate of a steroid or pharmaceutical in the WWTP is challenging as human enzymatic metabolism causes the bioactive chemical to exist in multiple forms - parent, Phase I and Phase II metabolites. Phase II metabolites predominate urine excretion and are the starting products entering the wastewater environment. They therefore act as the precursors to the biotransformations that take place during treatment and produce the Phase I and/or parent forms of the bioactive chemical. Before treatment technologies can be developed and evaluated for pharmaceutical and steroid removal in the WWTP, our understanding needs to improve on how the different bioactive chemical forms behave, and their relationships to each other. This means identifying the biotransformations between metabolites and parent forms. To achieve this requires a move from targeted analysis - we analyse for what we expect to see - to develop methods that are non-targeted and search for Phase II metabolites and their associated Phase I / parent forms. Drawing on inspiration from metabolomics approaches used in the biosciences, the aim of this proposal is to develop a novel non-target method to identify bioactive chemical Phase II metabolites and their biotransformation products in wastewater. Knowledge of Phase II metabolite occurrence and fate in the wastewater environment is important in assessing the impact of user behaviour, process and environmental factors or bioactive chemical parent removal. This will inform on WWTP efficiency, provide data for optimising models that predict pharmaceuticals and steroids, and evaluate environmental risk.

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.

The water industry is increasingly under pressure to achieve high standards of treated waste water discharges in particular in relation to nutrients, minimising carbon footprint, and at the same time, minimising capital and operational costs. This generates a new and challenging framework for waste water treatment technology optimisation to achieve, not only compliance, process robustness and resilience but also to reduce associated carbon and economic costs. Therefore, the water industry need new approaches to provide solutions for environmental and health protection. This programme examines new biological modelling approaches for a fixed film process (rotating biological contactor - RBC) which is one of the most prominent low energy technologies used at thousands of small scale treatment works in the UK. The purpose of this work is to explore the underlying mechanisms that influence and limit RBC performance through the development and application of a new approach to biological fixed film models for nutrient removal. Engineering aspects such as rotation speed, aeartion and media type are known to affect pollutant removal by the biofim. Recent advances in the understanding of biofilm development, nitrification process requirements, potential effects of rotational speed (Di Palma and Verdone 2009), and attempts to model oxygen transfer (Kubsad et al. 2004, Chavan and Mukherji 2008) provide a new opportunity for optimising and rationalising biofim modelling and thus RBC design and operation. The work programme will include a critical review of past approaches to RBC optimization and biofilm development models. In addition, data mining will be conducted on Severn Trent's records to characterise the robustness and resilience of the process. The project partner has over 350 small sewage works which have employed RBCs for secondary treatment of domestic waste waters throughout the past 20 years. Experimental trials will be conducted to validate the modelling approach. The project has a significant impact in the training of the researchers of the future. The doctoral student will be embedded within the water industry on a leading-edge research topic. The studnet will attend the Schools Research Training Programme (http://www.cranfield.ac.uk/soe/esrstp/) and so develop research investigation and communication skills. In addition technical training will be achieved through the completion of taught MSc models in the Centre for Water Science this will enable the researcher to possess expert knowledge in their specialist field of biological processes and also be able to deploy methods and techniques that balance social, environmental, economic, and engineering considerations. Whilst completing their research programme at Severn Trent they will receive business training relating to effective project management and will become familiar with business processes and client needs. The results from this work will provide a better understanding of a robust, low energy technology for achieving increasingly tighter demands for environmental and health protection, thus contributing both to the scientific understanding of processes within the reactors and informing the design of the technological application within the water industry. The project will necessarily entail the implementation of research methods from various disciplines, such as process engineering and environmental science among others, to deliver a biofim model and thus improved RBC operation and design that is robust not only in terms of treatment performance but is also embedding the importance of carbon footprint in waste water treatment process optimisation. The impact of this work will be to deliver a new modelling approach for biological fixed film processes which can be applied to thousands of sites to optimise pollutant removal at the lowest carbon cost.

Microalgae attract considerable interest due to their potential for the production of value-added products such as pharmaceuticals, nutraceuticals, animal feed, cosmetics and biodiesel. Although the applications for high value products are viable, applications for biodiesel production, with a lower value but much greater market potential, are still not economically viable due to the high cost of algal biomass production. The costs of growth medium and algal biomass harvesting have specifically been identified as the major contributions to the total cost of production and will have to be significantly reduced to enable widespread application. The use of wastewater as an algae growing medium has however been shown to be a sustainable low cost option as it provides the nutrients needed for algae growth while simultaneously delivering wastewater remediation. Applied to wastewater treatment, microalgae are proven to efficiently remove nutrients (phosphorus and nitrogen) to very low levels and also demonstrated potential to remove hazardous chemicals such as heavy metals and organic micro-pollutants. Essentially, microalgae can be used for wastewater pollution remediation whilst providing added value through the production of algal biomass. However, algae harvesting remains the major limitation and solving this problem will be the key to deliver the true potential of these technologies. Membrane photobioreactors, which are integrated systems combining an algal photobioreactors with a membrane for direct separation of the algal biomass have been identified as promising alternatives to more conventional algae systems as they generally have the same advantages as typical algal photobioreactors but the integrated membrane provides complete retention of algae cells and decoupled biomass and hydraulic retention times. This enables increased biomass concentrations and consequently intensification of the process with significantly shorter contact times. While the membrane facilitates algal biomass harvesting, as for all membrane systems, fouling becomes the main limitation. The accumulation on the membrane of the algal biomass and any organic and inorganic compounds present in the water will affect its hydraulic performance and contribute to an increase in energy demand and costs. Membrane fouling is inevitable so it will be critical to control its formation through the implementation of mitigation measures to obtain sustainable operation and to make the technology economically viable. Previous studies on membrane fouling by microalgae have highlighted the highly fouling nature of algogenic organic matter and more specifically the soluble biopolymers excreted by microalgae. Importantly, biopolymers have been shown to be the main contributors to irreversible fouling as they can penetrate in the pores of the membrane and block the channels, significantly affecting membrane filtration performance and cleaning requirements. Interestingly, biopolymers have also been shown to naturally aggregate in some systems. Promoting clustering would then enable to transfer the highly fouling compounds from the soluble to the particulate fraction in which case the biopolymer clusters formed can no longer enter the pores of the membrane and will only contribute to the formation of cake layer on the surface of the membrane, which is essentially reversible. This will then lead to a reduced impact on the filtration performance and decreased costs of operation therefore making the technology economically viable. The aim of this research is then to develop a sustainable and economically viable algae based technology for wastewater treatment and algal biomass production for resource recovery by establishing the basis for controlled biopolymer clusters formation in membrane photo-bioreactors treating wastewater and demonstrating the beneficial impact of the particulate biopolymer assemblages on the reversibility of membrane fouling.