Melissa Poma – MicroFuelPro: Microbial fuel development framework using synthetic biology for next generation drop-in renewable fuel production
Supervisor: Dr Ulugbek Azimov
The employment of bacteria as cell factories is an attractive means for sustainable large production of energy molecules. Bioengineering research have made impressive progresses in identifying and optimizing microbial metabolic pathways involved in the biosynthesis of fuel-like hydrocarbons. Such metabolic routes include: derivations of amino acid pathway, the mevalonate pathway, the polyketide pathway, and the fatty acid pathway. These natural metabolic routes have been engineered and modestly implemented in native and non-native hosts, enabling the microbial cell to assimilate simple sugars into value-added molecules. However, industrial production rate has not been achieved yet, moreover, this biosynthesis cannot be considered entirely sustainable, unless it is decoupled from the use of simple sugars as feedstock.
MicroFuelPro project sets the challenge of enhancing metabolic fluxes to achieve large scale biofuel production through the microbial assimilation of waste material, such as lignocelluloses, into energy molecules. The direct conversion of waste materials into fuel-like molecules has not been fully explored, thus, the objective of the project will lies in the identification of genes that enable this catabolic and anabolic process efficiently.
An attractive candidate to host biofuel synthesis is the Gram-negative bacterium Zymomonas mobilis, which has a high substrate uptake and striking ethanol yield. However, Z. mobilis does not naturally degrade lignocellulose, hence, to provide it with this function, relevant genes will be identified in lignocellulolytic microorganisms and expressed in the host platform. Most likely, the solely heterologous expression of genes will not be sufficient to enable an efficient substrate assimilation, thus, further bioengineering tools (e.g. CRISPR, genome editing, ribosome binding molecules etc.) will be used to generate a synthetic high-performance metabolism. The same approach will be exerted in other different bacteria to synthesize compounds such as fatty acids, terpenoids, polyketides and higher alcohols. The pathways involved in these products synthesis will be either tweaked in native host or heterogously engineered in model bacteria that show features like high growth rate, high tolerance to solvent toxicity, or ability of metabolizing alternative feedstocks. The ultimate goal will be the comparison of an array of engineered bacteria to detect the most suitable candidates for lignocellulose biodegradation and conversion into value-added molecules.
After the production of fuel molecules, the fuel design properties will be identified, and surrogate fuel pallet will be chosen. Ideally, each palette compound would be representative of a class of compounds found in the target renewable fuel. The surrogate palette will contain representatives from each of the major hydrocarbon families found in market hydrocarbon fuels: n-alkanes, iso-alkanes, cycloalkanes, aromatics, and naphtho-aromatics. 13C (carbon) and 1H (proton) nuclear magnetic resonance (NMR) spectroscopy and GC-MS will be used to quantify the compositional characteristics of each target renewable fuel in this study.
The next step will be to identify and run an optimization study to determine how much of each palette compound should be included in the surrogate to achieve the property targets of renewable fuels. Once each surrogate composition is determined, the pure palette compounds will be blended together to produce the surrogates, and each surrogate will be tested to determine whether the property targets are achieved within their desired tolerances. The outcomes of the fuel design process will be correlated with the metabolic pathways. Through this analysis we will be able to identify and design the most efficient pathway not only in terms of yield but also in terms of fuel properties, sustainability and suitability to conventional and future power generation systems.
Ho Chi Wong – Spin dynamics in multilayer organic photovoltaics and organic light-emitting diode films
Supervisor: Dr Paul McGonigal
My project is a collaboration between Chemistry and Physics, which aims to develop new high-performing organic materials for multilayer organic devices such as organic photovoltaics (OPVs) and organic light-emitting diodes (OLEDs). We will also, for the first time, explore the use of ferromagnetic resonance spectroscopy (FMR) to characterise the spin states of these devices.
Spin-flip mechanisms are crucial to the design of efficient organic materials for renewable energy applications. The interplay of spin-singlet and spin-triplet excited states mediates the performance of solar-to-electricity energy generation in photovoltaics and electricity-to-light energy conversion in OLEDs. However, there are various factors which are still significantly restricting the efficiency of these devices. For example, the maximum efficiency for a single p-n junction photovoltaic cell is limited to below 33.7% by the Shockley-Queisser limit, whereas the internal quantum efficiency of singlet-state generation in OLEDs is limited to only 25% due to the spin-forbidden radiative decay from the triplet to singlet state.
Promising solutions to the problems mentioned above have been proposed. For example, the unique properties in certain organic semiconductors can be utilised to overcome the limitations of single-junction inorganic photovoltaics via singlet fission. Singlet fission is a process by which a high-energy singlet exciton is converted into two triplet excitons, each carrying about half the energy. Coupling such an organic semiconductor to a low band gap inorganic semiconductor allows fabrication of a two-bandgap OPV in a single junction, which will in principle have a higher efficiency than conventional photovoltaics. On the other hand, the use of fluorescence emitters which exhibit thermally activated delayed fluorescence (TADF) in OLEDs could be considered. By designing molecules with a small energy difference between the S1 and T1 levels, the small energy gap may enable reverse intersystem crossing to occur, where excitons in T1 are converted to S1 in a thermally activated process. Once in the S1 state the excitons will be able to decay back to the S0 ground state via fluorescence. Using the TADF mechanism, internal quantum efficiencies of 100 % can be achieved and it is hoped that TADF will allow the creation of a stable and high efficiency OLEDs.
The first stage of my project will, therefore, be the development of organic materials, focusing on highly conjugated systems such as acene derivatives that are predicted to undergo singlet fission. Once the new organic materials have been synthesised, they will be subjected to FMR spectroscopy to characterise their spin states. FMR probes spin flip and reverse intersystem crossing processes by measuring the precessional damping of magnetisation in an adjacent ferromagnetic thin-film spin source. It will give us direct access to the rates of the fundamental organic spin processes described above. Although FMR has rarely been used on organic materials, this approach has great potential in studying OPVs and OLEDs because it can be applied to probe the entire multilayer system. We hope that by developing high-performing materials for OPVs, and OLEDs, the broad applicability of these devices means that our technological developments could bring positive environmental impacts to society.
Ellie Grimes – Can you get more with less? Organic Photovoltaics for longer lifetime and lower cost via blending with commodity polymers
Supervisor: Prof Chris Groves
This research will focus on decreasing the cost of production and enhancing the lifetime of Organic Solar Cells (OSCs) by blending the active layer components with commodity polymers.
OSCs have, in recent years, been given a lot of attention due to their rapidly increasing power conversion efficiencies of up to 17%. However, little attention has been paid to their lifetime and cost of production. In order to meet increasing global energy demand in a sustainable manner the renewable technologies employed must have reasonably long lifetimes and low cost of production so they can compete with fossil fuels.
OSCs tend to have a lifetime in the order of days to months in ambient conditions; this is due to degradation by photooxidation in the presence of water and oxygen. This degradation is therefore a roadblock to their uptake. Self-encapsulation by the addition of commodity polymers may decrease the penetration of water vapour and oxygen preventing degradation and enhancing their lifetime.
Commodity polymers are insulating, inexpensive, readily available and some are even hygroscopic, meaning they can take on water. Integration of these molecules into the active layer can be easily achieved and could have positive effects. Although, the choice of the polymer is crucial as it can affect the morphology of the active layer and therefore can affect the inner workings of the cell. Therefore, more research is needed in order to identify suitable commodity polymers for specific donor acceptor systems.
Amanuel Woldeab – Self-sustained surface cleaning of solar energy systems
Supervisor: Dr Vincent Barrioz
Climate change is one of the biggest challenges facing today’s generation. Human activity is seen as primary cause for global warming, with overwhelming scientific evidence. Replacing conventional energy sources by renewable energy sources like wind, solar and tidal, is so far the best solution to the pressing situation, of which solar energy is playing a major role.
One of the major successes in the solar energy technology has been in lowering its levelized cost, which is now comparable to conventional energy sources. However, several glitches have been hindering its performance, one of the major problems being accumulation of dust on the surface of solar panels.
Accumulation of dirt, commonly known as soiling, reduces the power output of solar modules by attenuating the incident light. Research has shown, in arid climate conditions with little annual rainfall, more than 65% loss of power generation could occur due to this effect.
The aim of this project is to develop a system, accomplishing regular self-cleaning maintenance at a low cost, to prevent soiling on the surface of the solar panels. To date, several approaches have been implemented to clean solar panels which can be categorized as mechanical, electrodynamic screen and nano-films coating.
Mechanical cleaning method is done by either brushing, blowing, or vibrating. Generally, this method can cause surface damages and requires large amount of water and energy consumption to drive bulky component parts.
Electrodynamic screen cleaning method, originally developed for operations on Mars & Moon, works with the application of electric curtains. However, it is less effective on earth climate conditions (i.e. rain) due to water interference.
Nano-films coating cleaning method is accomplished by applying transparent self-cleaning nano films on the surface of solar panels. The film is generally made of hydrophilic or hydrophobic material to self-clean the surface. Both methods require the application of water, or other fluid, to function. The angle of contact (CA) of water droplet determines whether the surface is hydrophobic or hydrophilic. The surface texture can be enhanced by decreasing the water CA to less than 5º to create super hydrophilic coating and increasing it to more than 150º to create hydrophobic coating.
The project will look at preparing super hydrophilic (or hydrophobic) coatings with excellent dust removing efficiency and antireflecting property. In this approach, a film of a particular fluid will flow on the surface to clean the dirt off the solar panel surface.
Nano-films with high level of transparency and hydrophilic nature will be developed. Adding impurities to the nano-films (and/or the fluid) such as TiO2 can provide added value, increasing the rate of contaminant degradation process by improving its photo response from UV range to visible light region. When light is radiated on a film such as TiO2, any contaminant on its surface is continuously decomposed by photooxidation process, making it easily washable with the application of water.
Two types of approach will be explored to prepare the nano-films namely top down or bottom up. In the top down method template-based technique, photolithographic and plasma treatment of surfaces approaches will be followed. The bottom up methods are like chemical deposition, layer by layer deposition, hydrogen bonding or colloidal assemblies. The nano coating requires a moving fluid for cleaning, hence a low cost but effective means of fluid delivery system will be designed.
The project will also involve CFD simulation (or ANSYS) to establish a 2D model of water film on various inclined flat solid surface to analyse the spreading velocity of fluid moving on the nano coated surface and determine how effectively it washes away contaminants.
This project ultimately will look into improving the performance of solar energy technology by avoiding power losses due to surface soiling. Accordingly, it aligns with the EPSRC Energy Theme, with the mission to position the UK to meet its energy and environmental targets and policy goals.
Michael Jones – Back contact engineering for high performance kesterite solar cells
Supervisor: Dr Yongtao Qu
With the world’s ever-increasing need for sustainable energy renewables could not be more important. With this said one of the most promising areas for large scale deployment of renewable energy is photovoltaic technologies. Panels with Silicon based absorber layers are widely deployed for commercial and home energy production, however they have weak absorption characteristics in comparison to some third-generation photovoltaics. This gives rise to thin-film photovoltaics as a promising future technology. One specific type of absorber that has shown promising absorption characteristics (with an absorption coefficient of α=104) is known as CZTS, Copper Zinc Tin Sulphide.
CZTS based photovoltaics are made from earth-abundant, non-toxic chemicals for both sustainable energy generation and production methods. CZTS devices can be manufactured with solution-based processing methods for scalable and low-cost production. These facts cement CZTS third generation PV technologies as a viable option for future energy production. However, CZTS has only reached a maximum efficiency of 12.6% in 2014 and has yet to increase since. One large contributing factor to this limited efficiency is a small open circuit Voltage, which in turn reduces the maximum power output and device efficiency.
The limited value in VOC is a by-product of the annealing process. A soda-lime glass substrate is subject to deposition of Molybdenum to act as the back contact. This is followed by the deposition of CZTS nanoparticles which are then annealed in a tube furnace to increase grain size and reduce grain boundaries. During the annealing process a very thin layer of Mo(S,Se)2 is formed which decreases the VOC. This is due to the increased series resistance that the Mo(S,Se)2 layer causes which thus decreases the electrostatic potential and causes an increase in electron-hole pair recombination. This is one of the main barriers to an increase in CZTS device efficiency.
One way to combat this limitation is to peel off the absorber layer from the Glass/Mo/ Mo(S,Se)2 structure and to deposit a more desirable back contact material on the underside of the absorber layer. A more desirable back contact will have a higher conductivity than Mo(S,Se)2 so the end device has a lower series resistance. One such material that can be used is MoO3. MoO3 can be deposited by sputtering or thermal evaporation to decrease the series resistance of the device.
My project will be mainly focused on improving the device VOC by achieving the peel off process to deposit a more conducting back contact on the underside of the absorber layer. The peel off process can be achieved by exfoliation which will be one of the main focuses of my PhD. Once the first goal has been achieved with sufficiently good results and repeatability a suitable back contact such as MoO3 will be deposited. Following successful deposition an Au reflective capping layer will be deposited to increase light absorption. The final step will concern device fabrication and characterisation to determine Pmax, VOC and ISC. Along with SEM, Raman and XRD characterisation methods to obtain structural properties and morphology information.
A bonus activity that would be desirable to round off the research project would be to simulate the electrical conductivity and semiconductor absorption properties using python. This would be achieved by using the packages such as solcore. Using python-based simulations in comparison with experimental methods and results, an analysis of the peel off method and MoO3 deposition can be compared both theoretically and experimentally to understand the real-world advantages and applications of back contact engineering of thin-film PV cells.
Katie McConville – Flexible substrate rectenna devices for energy recovery
Supervisor: Dr Linzi Dodd
My research is focused on the usage of embroidered electronics to harvest energy in a wearable system. The primary material of research is PVDF (poly(vinylidene fluoride)), a semi-crystalline polymer that displays piezoelectric, pyroelectric and both photoelectric and photovoltaic characteristics.
Each aspect of the materials properties will be analysed, with a focus on the piezoelectricity in its fibre form, but also a look at how the properties varies when used as a thin film. This film form is where the material appears to have the most potential as a photovoltaic. Which form is best for use as a pyroelectric is still to be investigated.
Piezoelectricity occurs when a material undergoes mechanical deformation (compression, twisting) which generates a voltage. Pyroelectricity is when a material is heated or cooled, and this generates a voltage. Both of these occur due to the asymmetric structure of the material that allows ions to move through it easily. Photovoltaics is when electromagnetic radiation hits a material, and gives energy to an electron, causing it to move within the material.
There are a number of papers working on the improvement of the materials efficiencies, which seems to be a lengthy and expensive process. I aim to use a commercially available PVDF fibre as my basis, to develop a series of embroidered patterns and woven fabrics to investigate how PVDF can best be used to harvest energy, and the practical applications of these systems. As part of this, a direct comparison will be undertaken with the fibres developed by other teams. For this, I will be mimicking their extrusion methods, both melt-spinning and fibre drawing, and using them in the same systems proved to be most efficient by the commercially available fibre.
To support this, physical analysis of the fibre material will take place, to create a baseline of what changes between fibres have valuable effects. This will include a look at its crystalline structure, and an analysis of whether poling the material increases efficiency enough for it to be considered a valuable part of developing it industrially. This will make it simpler to predict the results of future designs.
One application already being investigated with regards to piezoelectricity is the material’s potential as a gait sensor, with an aim of detecting medical conditions. This fits in with EPSRC’s theme of Healthcare Technologies. As part of a self-powering system, this could also have potential applications for athletes, and as a pedometer in personal fitness systems. If it proves to have a reasonable efficiency in a woven fabric, wind energy harvesting and clothing applications are possible. Worn self-powering systems would be an improvement for the field of personal sensors and devices.
If the material proves to have usage as a pyroelectric, the next step will be to test it in a number of practical uses, such as incorporation in an infrared rectenna system, to harvest energy from places of heat, including car exhausts. However, as a polymer, there is potential for thermal degradation. The balance of heat harvesting versus material breakdown will be a key point of this work.
The photovoltaic aspects of the material are recorded as being low in efficiency. This property will still be investigated, in the aim of creating an improvement in efficiency. If this is possible, and the material also proves to have pyroelectric properties, work will be done to develop both properties in one system. PVDF is already used as an additional layer to improve the efficiency of solar cells.
The final objective of this project is to develop practical and usable in real life methods of energy harvesting using PVDF.
Luke Haworth – Hybrid piezoelectric films and smart icephobic coatings with acoustic wave strategies for active ice protection
Supervisor: Dr Ulugbek Azimov
Ice buildup (via super-cold humid air, frost formation, frozen condensation or freezing rain) poses significant operational and safety challenges on wind/marine turbines and aeroplanes. For wind energy generation, these turbines often suffer significant drops in efficiency/production, severe damages or accidents. Ice accumulated on aircraft during flight seriously deteriorates aerodynamic performance and may lead to disasters.
The key aim of this project is to research hybrid smart thin materials combining piezoelectric films (such as doped-ZnO) and inherently icephobic surface/coatings, to generate surface acoustic waves (SAWs), which are used as anti-icing and de-icing mechanisms to mitigate real-time ice issues for the wind turbines. The innovative idea is to research hybrid piezoelectric thin films to generate SAWs directly onto surfaces of structures which can then excite a synergistic mechano-thermal effect for both anti-icing/de-icing functions, and to simultaneously perform ice sensing using these thin film acoustic wave devices. A key advantage of this developed smart thin film material platform with icephobic coatings is its seamless integration onto surfaces of turbine blades with energy efficient and wireless actuation/control/sensing functions. Some of the work will include the experimental investigation of droplet impact with low-temperature droplets and on low-temperature surfaces in order to simulate the effect of cold climates on both wind turbines and aircraft.
The project has the following key research work: (1) Design/deposit/characterize advanced piezoelectric doped ZnO films on turbine blade materials (for example, aluminium plates) using magnetron sputtering deposition. (2) Design, fabricate and simulate thin film material SAWs and investigate their piezoelectric and acoustic wave properties, focusing on multilayer based vibration modes and thermal effects. (3) Smart icephobic surfaces and coatings (including SAW compatible superhydrophobic/SLIPS/SOCAL/CYTop/elastic coatings). (4) Thin film piezoelectric materials for integrated ice sensing and monitoring. (5) Anti-icing/de-icing performance using thin film acoustic waves with smart icephobic coating materials.
Edward Land – Flexible coupled multi-body dynamic research of floating offshore wind turbines
Supervisor: Dr Zhiqiang Hu
Part of the UK’s National Energy and Climate Plan is to seek, in cooperation with the EU to support the delivery of cost-effective, clean, and secure supplies of energy with a large part of this is to come from harnessing offshore wind in the North Sea. The European Commission has estimated that offshore wind from the North Seas can cover up to 12% of the electric power consumption in the EU by 2030. To do this offshore wind turbines are having to be built to operate in deeper waters and further offshore which allows for higher and more consistent wind loads as well as greater public acceptance due to lower visual and environmental impacts that otherwise accompany offshore wind turbines. However, as this happens it becomes increasingly economically viable to mount the wind turbine on a floating structure which is tethered to the sea floor rather than conventional methods of using a concrete anchor or driven monopoles. But the wind industry is facing many challenges on the design, manufacturing, installation, operation and maintenance of floating offshore wind turbines (FOWT), and among which the most critical challenge is the reliable methodology for predicting nonlinear dynamic responses of FOWT under complicated sea states.
The FOWT is a typical rigid-flexible multi-body system, as such it must not only remain buoyant but also limit responses in pitch, roll and heave as well as maintaining position in a large variety of conditions. Excessive responses can lead to higher structural stresses and as such would incur higher costs to make the system structurally sound compared to a system encountering smaller responses, the efficiency of the turbine is also reduced by large rotational responses in pitch and roll which would also add additional wearing onto the turbine components increasing the need for repair and maintenance. As such being able to predict the responses of a FOWT system due to the multiple loads it is put under and reduce them would be required for cost-effective, efficient, and safe designs.
The aim of this project is to improve the accuracy of dynamic response prediction of FOWTs and to develop a numerical programme to solve the aero-hydro-elastic-mooring-servo coupled equations of a FOWT. This project is undertaken in partnership between Newcastle University, the ReNU Centre for Doctoral Training, and the Offshore Renewable Energy Catapult.
This aero-hydro-elastic-mooring-servo numerical programme will consider the loads from aerodynamics, hydrodynamics, and mooring lines acting on the FOWT in various conditions, this will be coupled with structural and multi-body dynamics in order to predict the response of the FOWT in various sea states. Furthermore, control theory will be applied to discern methods of damping and reducing the responses of the FOWT using control systems. It will allow designers to consider different floating body concepts and which concept of floating body would be suitable for the area of operation that the FOWT will be placed in. The programme will be applied for code-to-code comparison with other codes as well as with published basin experimental data or full-scale measured data. It will also be applied in industry practice with a 7MW FOWT with the support of the Offshore Renewable Energy Catapult.
Jack Reeder – TBC
Supervisor: Dr Marloes Peeters
The growing demand for water and energy has become a critical issue for sustainable societal development with >2.5 billion people lacking access to adequate water sanitation and electricity not available to >1.3 billion people. Wastewater is increasingly seen as a valuable potential energy source; however, extraction of energy from wastewater by anaerobic digestion leads to the formation of the greenhouse gas methane. Microbial fuel cells (MFC) hold great promise since this green technology converts organic energy in wastewater into electricity, simultaneously producing energy and treating wastewater. The performance of MFCs strongly depends on the anode since this affects electron transfer, oxidation rate, and where (electroactive) bacteria attach. Currently, graphite electrodes are commonly used which have the drawbacks of weak electrocatalytic activity and limited adhesion sites for bacteria.
The objectives of this project are:
In first instance, we will characterise the wastewater composition to determine which bacteria are present, and search in literature which of those will enhance MFC activity. Subsequently, we will manufacture surface-imprinted polymers, which are polymers that are imprinted with the target bacteria of interest. After removal of the template, cavities remain behind that are complementary to the size, shape, and chemical functionality of the original target. We might consider “dummy” template approaches, which involve using latex beads with similar size and functionality to the original bacteria, which does not require special health and safety considerations. First, we will focus on acrylamide and urethane-based polymers as previously reported in literature. Second, we will use rational design approaches to synthesize new monomers that are specifically designed to interact with the bacteria (based on interactions with groups present on the surface, which includes for instance sugar groups).
This is a multidisciplinary project which is a collaboration between bioengineers, microbiologists, chemical engineers, and chemists. We will create novel materials for sustainable energy systems; these materials might also have applications in healthcare since they can be used for bacterial sensing. The project addresses a number of EPSRC areas such as bioenergy, electrochemical sciences, and materials for energy applications.
Reece Paterson – Exploiting nanoparticles for thermal and light driven valorisation of carbon dioxide
Supervisor: Dr Simon Doherty
The rapid rise in the concentration of atmospheric CO2 over the past century has increased demand for alternative fuel sources to address climate change. Even a climate progressive nation such as the UK is currently failing to meet CO2 emission targets set by the Paris Agreement,1 hence there is significant pressure for the development of innovative technologies to overcome this global challenge. The UK government’s target to reach net-zero emissions by 2050 is to be partly facilitated by carbon sequestration. The UK’s largest carbon capture plant, due to be operational by 2021, hopes to capture 40,000 tonnes of CO2 per annum – equivalent to the emissions of 22,000 cars.
Both commercial and industrial applications of carbon dioxide are relatively limited, therefore these soon to be vast stores of captured CO2 present an exciting opportunity for an alternative fuel source. This project aims to develop metal nanoparticle catalysts that will facilitate both the thermal and photocatalytic reduction of CO2 to more valuable products such as formic acid which can serve as a hydrogen storage material, methanol which can act as a combustion fuel or as a C1-feedstock for the production of various fine chemicals, methane or even higher alkanes.
The principal focus of this work will be to employ functionalized polymer immobilized ionic liquids (PIIL) as supports to stabilize gold nanoparticles, control their growth (size distribution and shape), modify surface electronic properties and explore whether catalyst-support interactions can be used to control efficacy. PIIL supports are advantageous over bespoke ligands as they are more affordable, robust, and are not prone to leaching enabling the catalyst to be recovered and recycled. The Doherty group has previously found that PIIL supports are highly beneficial in promoting the activity, stability, and selectivity of gold nanoparticle catalysts towards the reduction of small molecules. Reports have shown that polymeric ionic liquids also have a high CO2 absorption capacity in addition to fast rates of CO2 adsorption/desorption,3 therefore we intend to extend this technology towards the thermal and light driven reduction of CO2. Advanced analytical techniques such as TEM, XPS, EDX, powder-XRD, TGA and solid-state NMR spectroscopy will be utilized to determine the catalyst composition while DRIFT, XPS and in situ FTIR will be used to probe the catalyst surface and to study CO2 adsorption. A detailed understanding of surface-support interactions will provide insight on the factors that influence catalyst activity and product distribution, facilitating the development of an optimum catalyst with a stable activity profile suitable for scale-up.
Sergio Serrano Blanco – Novel materials for intensified bioenergetic biomass production and aquaculture wastewater treatment
Supervisor: Dr Sharon Velasquez Orta
The growing energy and water demand over the last centuries has resulted on an increase in greenhouse gases, wastewater effluents and a depletion on fossil fuels. Wastewater must be treated before returning to the environment. Therefore, the quest for sustainable and environmentally friendly wastewater treatment and energy provision has become imperative. Environmental policy strategies (e.g. Sustainable Development Goals, SDG from the UN or The Knowledge Centre for Bioeconomy of the European Comission) have been set up in Europe and across the world for the next half century in order to boost the growth of bio-based products to address energy challenges. In particular, the production of biofuels generated from microalgal biomass has received an increasing interest due to its greater energy security, reduced environmental impact and higher biomass productivities than land crops.
Microalgae are unicellular or multicellular photosynthetic organisms whose biochemical properties make them a useful tool to transform the energy sector into a more environmentally friendly based industry. These diverse light-driven microorganisms can thrive in a wide spectrum of environmental conditions due to their flexible metabolism which enables them to produce a vast range of metabolites that can be biotechnologically processed to biofuels, feed, drugs or wastewater treatment agents. However, large-scale cultivation still remains economically challenging due to high operational cost, water and down-streaming energy use. Using fertilizers to supply nutrients such as nitrogen or phosphorus and other micronutrients as microalgal growth medium can imply up to half of the cultivation cost. In order to cut costs, one strategy is to replace these commercially available nutrients with wastewater nutrients. Following this approach, the present project aims to address this operational drawback by using wastewater from intensive fish farming effluents which has high loads of nitrogen and phosphorous.
Due to the increasing amount of wastewater produced by aquaculture this could represent an alternative source of macronutrients to cultivate microalgal biomass whereas removing the excess of nutrients from wastewater. Current treatment systems used to remove high nutrient wastewater loads, such as biological nitrification/denitrification, chemical stripping and absorption or chemical precipitation, are efficient but produce carbon dioxide emissions and/or toxic sludge. This PhD project will look into increasing the amount of microalgal biomass produced from aquaculture wastewater treatment by assessing several novel shapes of 3D-printed translucid plastic materials in the form of beads, large spheres, rings or saddles. Materials 3D-printed have been shown to improve denitrification process in bacteria by promoting and controlling biofilms generation. Successful systems have already been commercialised for nitrifying microorganisms, however, the use of 3D-printed materials in microalgal cultivation to improve biomass generation remains to be explored. Microalgal cultivation provides the conversion of both, carbon dioxide to oxygen, and contaminant nutrients to algal biomass which can be converted to energetic products such as biodiesel. By cultivating microalgae along with novel materials, it is expected to increase biomass loads, and nutrient removals. Microalgae produced using this approach will be harvested by flotation, characterised and assessed for product conversion. The first phase of the experiments will be developed on a bench-scale in order to determine and characterise optimal conditions. This initial proof of concept phase will work towards setting-up and studying a system that can be transferred to large scale cultivation at the industrial partner premises.
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