School of Water, Energy and Environment (SWEE)
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Item Open Access Adaptation of two-stage vertical flow constructed wetlands for treating unscreened sewage in the UK.(Cranfield University, 2019-03) Khomenko, Olha; Bajón Fernández, Yadira; Dotro, GabrielaThe UK water industry has made a priority of embracing low energy sewage treatment, making of two-stage vertical flow constructed wetlands (VFCWs) a plausible alternative to conventional systems. However, for successful implementation of the technology in the UK a further understanding of any required adaptations in its design and operation is required, in particular linked to the UK use of spot sampling regulation of treated effluents and differences in rain profile affecting hydraulic loads in combined sewers. There is also a paucity of information regarding required time for full maturation of the technology and of performance during early operation. In response, the first UK full-scale WWTP based on two-stage VFCWs was built in Derbyshire, UK, and closely monitored during the initial three years of operation, allowing investigation of the system performance and robustness. The efficacy of the system for removal of total suspended solids (TSS), BOD₅ and NH₄ +- N has been evaluated by composite and spot samples analysis. The technology was found to efficiently remove pollutants to the level of 6 ± 3 mg·L⁻ ¹ , 5 ± 2 mg·L⁻ ¹ and 5.8 ± 3.8 mg·L⁻ ¹ for TSS, BOD₅ and NH₄+- N, for 24 hour composite samples. After one year of operation the system was retrofitted with forced aeration on the second stage, which enabled a higher ammonia removal with concentrations in final effluent of 95th percentile concentration of 5.3 mg∙L⁻ ¹comparing to 9.6 mg∙L⁻ ¹achieved in the system with passive aeration. The first stage filters were observed to be hydraulically limited during the first year of operation, with a hydraulic conductivity (HC) of <5.7× 10⁻⁶ m∙s⁻ ¹ which caused prolonged ponding occurrence. This in turn led to poor re-oxygenation of the first stage filter beds and low mineralization of the sludge layer deposited on its surface, which was characterized by TS and VS content of 11.5% ± 1.9% and 64.5% ± 7.3% respectively. A more mineralised sludge layer was present after three operational years, with HC <4.9 × 10⁻⁴ m∙s⁻ ¹ and sludge properties of 20.4% ± 3.5% TS and 62.3% ± 3.5% VS. These values are comparable to data reported for two-stage VFCWs operated in France and ponding was minimal after three years, suggesting this as the required length for system maturation. Close monitoring of the system during the first three years of operation evidenced the need to adapt rotating period lengths according to system age and sludge layer properties. Resting periods of up to 14 days were required for the young system to encourage sufficient hydraulic conductivity of the sludge layer, while the conventional 3.5 days feed/ 7 days rest cycle is appropriate after three years of operation. The influence of sludge properties on permeability was assessed in laboratory experiments, as well as artificial modifications of the sludge surface that could sustain increased permeability and accelerate sludge layer mineralisation. A positive impact of increased VS on permeability was found, with an increase in VS from 60% to 75% improving permeability from 6.14 × 10⁻ ¹⁷ m∙s⁻ ¹ to 2.00 × 10⁻ ¹⁶ m∙s⁻ ¹ in samples with TS of 9% and from 2.06E × 10⁻ ¹⁷ m∙s⁻ ¹ to 1.25 × 10⁻ ¹⁶ m∙s⁻ ¹ in samples with TS 15%. A greater relative contribution to permeability of preferential flow pathways (PFPs) present in the sludge layer than of sludge properties (TS, VS) was observed. PFPs were scarce in the young full scale primary VFCWs, which was believed to be the reason for their poor hydraulic acceptance. A positive effect on PFP formation and sludge drying rate was observed when artificially modifying the sludge layer by application of secondary activated sludge or by making initial cuts on its surface. Artificial modifications of the sludge layer could be implemented in full-scale systems to improve hydraulic acceptance and re-oxygenation, to shorten maturation of primary filters and to maintain prolonged operational periods without desludging.Item Open Access Advanced data-driven methods for prognostics and life extension of assets using condition monitoring and sensor data.(Cranfield University, 2021-12) Ochella, Sunday Moses; Sansom, Christopher L.; Shafiee, MahmoodA considerable number of engineering assets are fast reaching and operating beyond their orignal design lives. This is the case across various industrial sectors, including oil and gas, wind energy, nuclear energy, etc. Another interesting evolution is the on-going advancement in cyber-physical systems (CPS), where assets within an industrial plant are now interconnected. Consequently, conventional ways of progressing engineering assets beyond their original design lives would need to change. This is the fundamental research gap that this PhD sets out to address. Due to the complexity of CPS assets, modelling their failure cannot be simplistically or analytically achieved as was the case with older assets. This research is a completely novel attempt at using advanced analytics techniques to address the core aspects of asset life extension (LE). The obvious challenge in a system with several pieces of disparate equipment under condition monitoring is how to identify those that need attention and prioritise them. To address this gap, a technique which combined machine learning algorithms and practices from reliability-centered maintenance was developed, along with the use of a novel health condition index called the potential failure interval factor (PFIF). The PFIF was shown to be a good indicator of asset health states, thus enabling the categorisation of equipment as “healthy”, “good ” or “soon-to-fail”. LE strategies were then devoted to the vulnerable group labelled “good – monitor” and “soon-to-fail”. Furthermore, a class of artificial intelligence (AI) algorithms known as Bayesian Neural Networks (BNNs) were used in predicting the remaining useful life (RUL) for the vulnerable assets. The novelty in this was the implicit modelling of the aleatoric and epistemic uncertainties in the RUL prediction, thus yielding interpretable predictions that were useful for LE decision-making. An advanced analytics approach to LE decision-making was then proposed, with the novelty of implementing LE as an on-going series of activities, similar to operation and maintenance (O&M). LE strategies would therefore be implemented at the system, sub-system or component level, meshing seamlessly with O&M, albeit with the clear goal of extending the useful life of the overall asset. The research findings buttress the need for a paradigm shift, from conventional ways of implementing LE in the form of a project at the end of design life, to a more systematic approach based on advanced analytics.Item Open Access Advanced quadrotor control strategies for health monitoring of overhead power lines.(Cranfield University, 2021-07) Foudeh, Husam; Luk, Patrick Chi-Kwong; Whidborne, James F.Research into autonomous control and behavior of mobile vehicles has become increasingly widespread. In particular, unmanned aerial vehicles (UAVs) have seen an upsurge of interest and of the many UAVs available, the multirotor has shown significant potential in monitoring and surveillance tasks. The objective of this research’s programme is to develop novel control that enable quadrotors to track and inspect on high voltage electricity networks. This is a research application that has elicited little attention. This thesis provides a succinct and comprehensive literature research in both state-of-art overhead power lines (OPL) inspection technologies, and quadrotor design and control. It proceeds to motivate, develop and evaluate a learning algorithms controller which exploit the repeated nature of the fault-finding task. Very few iterative learning control (ILC) algorithms have been implemented in this area, and no analysis or practical results exist to specifically investigate UAV performance to modelling uncertainty and exogenous disturbances. In particular, novel contributions are made in ILC algorithms are derived and validated by experimental results on an AscTec Hummingbird quadrotor. It has taken a robust comparisons among several ILC approaches (gradient-based, norm optimal and Newton method ICLs), and the comparisons are largely based on analytical calculated results. In the case of optimal ILC approaches, a new algorithm for nonlinear MIMO systems is developed to cope with exogenous disturbances and noise severely affect UAV as well as a novel tuning method for bnew variation is formulated and applied to the problem of reference tracking for a 6-degree-of-freedom UAV with a two-loop structure. The first loop addresses the system lag and another tackles the possibility of a disturbance commonly encountered when inspection of OPL. The new algorithm contributes to good trajectory tracking and very good convergence speed while minimizing disturbance effects. A linearisation design approach has been extended to enable new updates using quadcopters dynamics. Then constraints have embedded to meet the application demands. After overcoming this deficiency, the ILC controller is further extended based on point-to-point through a straight conductor to fulfil the full task and perform a 2-3 sequence of operations. Finally, the ILC development results are given follow-up using 3D analysis approach where these results are the first ever in this key area.Item Unknown Advanced reactor technology for wastewater treatment.(Cranfield University, 2015-04) Hassard, Francis; Stephenson, Tom; Cartmell, EliseElevated stringency regarding discharges and an aging asset base represent challenges to modern wastewater treatment. This requires upgrade of existing wastewater assets for low energy nutrient removal for minimal cost. Advanced rotating biofilm reactors can be used as a pre-treatment, high organic loading rate (OLR), low hydraulic residence time (HRT) treatment facilitating upgrade of existing wastewater treatment plant (WWTP). The threshold for stable nitrification in rotating biological contactors (RBCs) was assumed to be 15 g.BOD₅.m⁻²d⁻¹ however media modifications have shown that this value can be elevated to ~35 g.sCOD.m⁻²d⁻¹ (73.5 g.BOD₅.m⁻²d⁻¹ ) in rotating biofilm reactors (RBR). Mesh media was compared to two different reticulated foam media, the mesh media had similar porosities but elevated performance compared to the foam media. Elevated OLR resulted in lower volumetric bacterial viability suggesting inhibition at >100 g.sCOD.m⁻²d⁻¹. Comparison of four different mesh media suggested that high porosity mesh media is best for performance and to prevent pore clogging. Bacterial specific activity increased with OLR, but performance at very high OLR decreased. Biofilm reactors can be operated in a ‘hybrid’ configuration where settled bacterial solids can be recycled into the biofilm reactor to improve performance by reducing the effective biofilm OLR. Studies at full scale revealed that extracellular enzyme activity was higher in biofilms compared to suspended growth bacteria. Hybrid upgrade of existing wastewater treatment works resulted in 52 and 40% increase in removal rate of COD and NH₄-N respectively. Comparing different solids type for hybrid reactors utilising activated sludge flocs had the greatest performance benefit compared to HS and FE respectively for sCOD and NH₄-N removal. Incorporating a solids feed in hybrid reactors improved nitrification and organics removal at lower loading. However the solids in the recycle feed reduced denitrification at very high OLR suggesting flocs inhibit denitrification. Hybrid RBRs have 4.8 fold increase in protein EEA compared to single pass reactors under similar conditions. Recycling bacterial solids reduces the effective OLR on the biofilm and confers significant performance benefits. Upfront RBRs provide suitable upgrade for existing WWTP.Item Unknown Advanced reliability analysis of complex offshore Energy systems subject to condition based maintenance.(Cranfield University, 2021-04) Elusakin, Tobiloba; Simms, Nigel J.; Shafiee, MahmoodAs the demand for energy in our world today continues to increase and conventional reserves become less available, energy companies find themselves moving further offshore and into more remote locations for the promise of higher recoverable reserves. This has been accompanied by increased technical, safety and economic risks as the unpredictable and dynamic conditions provide a challenge for the reliable and safe operation of both oil and gas (O&G) and offshore wind energy assets. Condition-based maintenance (CBM) is growing in popularity and application in offshore energy production, and its integration into the reliability analysis process allows for more accurate representation of system performance. Advanced reliability analysis while taking condition-based maintenance (CBM) into account can be employed by researchers and practitioners to develop a better understanding of complex system behaviour in order to improve reliability allocation as well as operation and maintenance (O&M). The aim of this study is therefore to develop models for reliability analysis which take into account dynamic offshore conditions as well as condition-based maintenance (CBM) for improved reliability and O&M. To achieve this aim, models based on the stochastic petri net (SPN) and dynamic Bayesian network (DBN) techniques are developed to analyse the reliability and optimise the O&M of complex offshore energy assets. These models are built to take into account the non-binary nature, maintenance regime and repairability of most offshore energy systems. The models are then tested using benchmark case studies such as a subsea blowout preventer, a floating offshore wind turbine (FOWT), an offshore wind turbine (OWT) gearbox and an OWT monopile. Results from these analyses reveal that the incorporation of degradation and CBM can indeed be done and significantly influence the reliability analysis and O&M planning of offshore energy assets.Item Unknown An agent-based model for improving museum design to enhance visitor experience.(Cranfield University, 2022-11) Ji, Yijing; Tran, Trung Hieu; Simon, Jude; Williams, LeonMuseum experience is a multi-layered journey including ontological, sensory, intellectual, aesthetic, and social aspects. In recent years, the museum sector has faced a number of challenges in terms of the need to enhance the potential of the experience while maintaining authenticity and credibility. For public science communication in museums, exhibition is an important medium for connecting exhibits and visitors, and as such, the study of visitors' senses and behaviours under impact of various museum layout designs has become an important research direction. The purpose of this study is to explore the recall of visitors' memories in the exhibition space by integrating images, echoes and tactile senses, and then transform memories and interactions into their own experience and knowledge base. The impact of spatial design and other design elements on visitors' memories is also explored. We have conducted Agent-based simulation, by setting up virtual visitors, exhibition spaces and artefact based on real gallery spaces, as a time-saving and cost-saving method to improve exhibition interactivity and content coherence. Meanwhile, through the simulation of this novel way, visitors can observe and predict the interactive experience between visitors and the exhibition, so as to improve the curatorial team's research on tourist behaviour and spatial design scheme. Next, the simulated data on visitors' memory recall behaviour is compared with the actual observed data to explore the authenticity of visitors' behaviour in the simulated museum. The impact of this study is by integrating a variety of shared understandings between curators, exhibition management and participants, drawing on diverse information based on experience, practice and simulation. It seeks to provide future museum- oriented practitioners, particularly in small and medium-sized museum exhibition spaces, with a novel perspective and approach to observing or predicting the experience of visitors' sensory interactions within an exhibition. Furthermore, at the same time as enhancing the visitor’s exhibition experience, the content of exhibition story is fully transformed into its own knowledge accumulation.Item Unknown Algae reactors for wastewater treatment(Cranfield University, 2016-02) Whitton, Rachel Louise; Jefferson, Bruce; Villa, RaffaellaThe onset of the Water Framework Directive (WFD) will challenge water utilities to further reduce their wastewater phosphorus discharges to < 0.5 mg.L- 1 . Whilst conventional treatments, such as chemical dosing, are able to meet these new discharge consents, the strategies are representative of a linear economy model where resources are unrecovered and disposed. An alternative solution which can contribute to the aspiration of a circular economy is microalgae. Microalgae are ubiquitous in wastewater environments and assimilate phosphorus during their growth, to residual concentrations complementary of the WFD. Furthermore, microalgal biomass can be anaerobically digested to produce biomethane offering the potential for an energy neutral approach. However, uptake of microalgal systems are lacking in the UK through limited knowledge of operation; and the belief that such solutions are synonymous to large, shallow open ponds with extensive treatment times. The development of alternative microalgal reactors are increasingly investigated to overcome these implementation challenges. Of these, immobilised microalgae has shown great potential; and whilst within its infancy demonstrates the greatest opportunity for development and optimisation. This thesis determines the critical operational parameters that influence the remediation efficacy of immobilised microalgae for tertiary nutrient removal; including species selection, biomass concentration, treatment period and lighting; with recommendations for optimal performance. These recommendations are then applied to the design and operation of an immobilised bioreactor (IBR) to understand the key design and operating components that influence the overall economic viability. In doing so, the potential for an IBR to be economically viable, within the next decade, in comparison to traditional approaches are discussed.Item Unknown Alternative cropping practices for sustainable soil management and yield optimisation in asparagus.(Cranfield University, 2021-07) Maskova, Lucie; Simmons, Robert W.; Deeks, Lynda K.; De Baets, SarahAsparagus (Asparagus officinalis L.) is a high value perennial crop with long economic production period ranging between 10-20 years. Field operations associated with conventional UK asparagus production such as re-ridging and intensive foot and vehicular trafficking of the wheelings however run a danger of causing a range of negative environmental impacts and pose a risk to long-term asparagus productivity. Nonetheless, majority of British growers continues to cultivate asparagus in the conventional way due to a lack of alternatives to the conventional practice. The aim of this research is to critically evaluate the long-term efficacy of a set of potential best management practices (BMPs) targeted at preventing or remediating soil compaction in asparagus interrows, promoting root growth and increasing profitability of asparagus production. The research further aimed to quantify the impacts of annual re-ridging associated with the conventional production on soil compaction, root development, yields and on soil bio-chemical characteristics. The experimental field trial located in Herefordshire tested a range of potential BMPs inducing (i) companion cropping with either rye (Secale cereale L.) or mustard (Sinapis alba L.) which were re-ridged or non-ridged, (ii) interrow surface mulching with either straw mulch or compost which were re- ridged or non-ridged and (iii) a combination of tillage practices (ridging and shallow soil disturbance) applied to bare soil interrows. Treatments were applied annually from 2018-2020. This research showed that the field management practice currently adopted by the of British asparagus industry is unsustainable and poses high risks to both the soil environment and asparagus productivity. Key findings show that soil compaction, root growth, asparagus profitability and soil bio-chemistry in asparagus cropping systems can be effectively modified and managed by BMPs. Consequently, this research identified a set of BMPs to be considered for practical application.Item Unknown Application of artificial neural networks in the design of drainage systems in data-poor areas.(Cranfield University, 2022-06) Ellafi, Murad; Simmons, Robert W.; Deeks, Lynda K.Drainage has been identified as an often-neglected component of irrigated agriculture in arid and semi-arid areas. Even though it is accepted that drainage is often necessary to prevent waterlogging and salinity impacting productivity in irrigated agriculture, it is typically ignored when planning future irrigation schemes. Only 5 – 10% of the total irrigated land in Least Developed Countries (LDCs) that requires drainage is currently drained (compared to 25 – 30% in developed countries). This is partly due to a fundamental lack of spatially and temporally coherent datasets containing key input parameters for drainage models, local expertise and the high cost of drainage installation. Drainage simulation models can provide reliable predictions of multi-component systems to evaluate drainage system design over long periods (1 – 100 years). This study evaluated existing drainage simulation models (i.e. DRAINMOD, SWAP, ADAPT, RZWQM2, EPIC, WaSim and HYDRUS-1D) for their suitability to be applied in data-poor arid and semi-arid regions. Based on a selection criteria, the most applicable model for drainage design in arid and semi-arid areas was DRAINMOD. DRAINMOD, an agricultural drainage simulation model, is a versatile and readily available model that can be used to evaluate alternative drainage system designs. DRAINMOD requires several key inputs, including saturated hydraulic conductivity (Ksat), reference evapotranspiration (ET0) and the Electrical Conductivity of a saturated soil Extract (ECe). In LDCs, measuring these parameters is expensive and time-consuming. In addition, existing historic datasets are often spatially and temporally limited. Therefore, indirect approaches are needed to overcome incomplete data records that restrict drainage designs. This thesis evaluates the feasibility of applying indirect methods, with a focus on developing and validating the use of artificial neural networks (ANNs) using available historic measured datasets. The study data draws on the drainage design for Hammam Agricultural Project (HAP) and Eshkeda Agricultural Project (EAP), located in the south of Libya, north of the Sahara Desert. Soil texture, bulk density, field capacity, and wilting point were used to develop ANNs to predict Ksat which were significantly more accurate compared to widely adopted Pedotransfer functions (PTFs) such as Rosetta3. To calculate the daily ET0, average monthly maximum and minimum air temperature were used to develop ANNs. Arithmetic Averaging of Neighbouring Stations (AANS), MODAWEC and Era5-Land were among the indirect methods applied to predict ET0. Landsat 5 Surface Reflectance bands and the derived salinity indices were applied to develop ANNs to estimate ECe. The accuracy of the predicted values of Ksat, ET0 and ECe were evaluated by using statistical parameters such as coefficient of determination (R²), mean square error (MSE), and root mean square error (RMSE). The predicted Ksat and ET0 values were input to DRAINMOD to design drainage systems in EAP and HAP as compared to the optimum design based on measured data. The design focused on how accurately the predicted values were able to estimate drain spacing, relative yield, irrigation depth, and drainage discharge. The key findings showed that the accuracy of predicting Ksat greatly impacted predicting the optimum drain spacing and the associated relative yield. Accurate prediction of the optimum spacing between drains will reduce the overall cost by ensuring that the drains are not spaced too closely, but also lowers the risk of raising the water table and negatively impacting the yield by preventing the drains being installed on too wider a spacing. In addition, precisely predicting ET0 is essential to quantify the irrigation water requirement and drainage discharge. Finally, predicting soil salinity using remote sensing data can be used as an early warning tool to monitor irrigated lands affected by salinity, evaluate the performance of existing drainage systems, and indicate areas that need improvement. Future research recommendations identified by this research include the need for (1) critical evaluation of the accuracy of using ANNs and other machine learning approaches to predict other input parameters required for drainage design such as the water retention curve, depth of impermeable layer, hourly or daily rainfall, and initial water table depth. (2) development and validation of ANNs and other machine learning approaches that can predict Ksat, ET0, and ECe on a national level (Libya) and/or regional level (Middle East and North Africa) to overcome the challenge of incomplete data records that restrict drainage designs.Item Unknown The application of digital soil mapping to improve the resolution of national soil properties across Great Britain.(Cranfield University, 2018-10) Campbell, Grant; Corstanje, Ronald; Hannam, Jacqueline A.; Black, H. I. J.; Lilly, A.Many countries have created soil maps to illustrate the variety of soil properties and support how soils can be used. Traditional soil mapping by field survey and interpretation has been the most recognised form of soil mapping for many years and an effective way to capture a variable soil landscape. Such maps have enabled scientists and stakeholders to improve their understanding of relationships between soils and other landscape factors such as geology and land cover. However, with the amount of soil information growing and technology improving, Digital Soil Mapping (DSM) has been developed as an alternative approach to generate soil property predictions and to produce finer resolution soils data. Currently, DSM produces maps based on training of models with observed soils data and environmental covariates and then releases these to stakeholders to evaluate their utility. This PhD has taken a different approach by addressing stakeholder needs at the beginning of the process. The overall aim of this PhD was to improve the spatial resolution of soil properties across Great Britain (GB), as informed by stakeholders. Three main aims were identified. The first assessed what current soils data and information stakeholders currently use, and what improvements they want to see from future soil-related products. The second aim, using information from the questionnaire survey and a comparison of laboratory and analytical methods, is to develop DSM which could be applied across the whole of GB. This was done by comparing two modelling approaches: Boosted Regression Trees (BRTs) and Multivariate Adaptive Regression Splines (MARS) for mapping soil properties (loss-on-ignition, texture and pH) across two pilot areas. The characteristics of MARS and BRT models at both training and deployment stages are examined. The third outcome investigated how well the soil properties mapped across GB, building on the development of DSM in the pilot areas and whether they reflect expert pedological knowledge. This section also focusses on how suitable an independent validation dataset is at evaluating soil property predictions. This PhD has shown that stakeholders are aware of what soils data and information they are using and could clearly express what is needed to improve current maps. Wider use of soil information by non-soil experts would be improved by increasing data accessibility and user- friendly supporting materials. Fundamentally, most stakeholders require finer resolution than what is currently available which identifies an opportunity for DSM to fill some of this gap. To address these gaps and develop DSM across GB, this PhD focussed on mapping soil properties that were directly comparable across Scotland and England & Wales and also key to many stakeholder information needs. After investigation of laboratory and analytical methods from the two national soil surveys of Scotland and England & Wales, soil loss on ignition, soil texture and soil pH were chosen for developing DSM for GB. From the development of DSM, results showed that MARS models produced better statistical performances than BRTs for predicting soil properties within a training environment. However, when MARS models are deployed to larger areas, they extrapolate beyond their means and BRTs performed better. This is because MARS models perform more consistently when many variables are required. Furthermore, MARS models struggle with overfitting and missing data which subsequently leads to incorrect and unfeasible pedological relationships between soil properties. BRT models, despite not performing as well statistically, produce more consistent relationships between pedology and mapped soil properties. This is because BRT models introduce randomness in the boosting which reduces overfitting and improves the predictive performance. BRTs have shown to be more consistent in the mapping outputs than MARS because regressing to the mean is more favourable when most data matches up with one another. However, this does not necessarily mean that the full range of soils in these areas were being captured by the BRT model. This led to scaling up from the pilot areas to modelling soil properties across GB using a single regional BRT model and evaluating its performance. BRT modelling results for GB at 2D and 3D predict well for pH and LOI but less so for texture. Going forward, more data are required to produce more consistent modelling outputs especially for areas across GB where soil properties are not currently being predicted well. The GB modelling results also highlighted a poor performance of the model against an independent validation dataset. This is because the original data for both GB training and validation datasets were analysed and collected for different purposes. These datasets were taken at different time periods under a different sampling design. Furthermore, the data for both training and validation GB datasets were collected at different scales. At present, these first versions of soil property DSM maps for GB have produced variable results. However, this exercise has shown that the development of reliable DSM maps would benefit from interaction between pedologists, modellers and stakeholders to ensure that mapped outputs are of sufficient quality at adequate finer resolution and can be usable. Such DSM maps, alongside management recommendations, will help to address many global challenges associated to soils. However, DSM is not the panacea for all mapping needs. Until such time that DSM fully develops into DSA and adequately incorporates the breadth of information available in traditional soil maps, mapping from field survey and observation will continue to be necessary for stakeholders.Item Open Access Application of machine learning in assessment of combustion of liquified natural gas.(Cranfield University, 2021-05) Alexandropoulos, Christos Dimosthenis; Hanak, Dawid P.; Longhurst, PhilipThis work focuses on the implementation on carbon capture on ships which run on liquified natural gas (LNG). LNG ships present a real-world example of LNG as well as a study case for carbon capture on LNG combustion. There is also special interest for that as well, since the International Maritime Organization (IMO), imposed a limit of 0.5% wt. of sulphur content in ship fuel has been imposed from 2020 to reduce pollution emissions from global shipping activities. This initiative will lead to major changes since the previous limit was set at 3.5% wt., which broadened fuel options for ships. In addition, the IMO is developing a long-term plan to completely nullify shipping’s impact on CO₂ emissions by 2030. Consequently, stricter regulations will be imposed to marine activities worldwide. LNG fuel seems to be a promising solution. The sulphur emissions are lower, in compliance with the latest IMO regulations. Additionally, it has a greater energy density in comparison to traditional fuels, like heavy fuel oil (HFO). This paper aims to study the feasibility of a project, which equips an LNG fuelled ship with a carbon capture system. The study includes an examination of an on-board carbon capture system, by simulating the LNG engine as well as the carbon capture system in simulation software. The engine model chosen is the Wärtsilä 6L34DF. The results of these simulations are analysed to examine the correlation between the system’s variables and to evaluate the possibility of heat integration within the system. The economic feasibility of the project is then assessed, using economic data. The results show that heat integration is possible. For example, the heat provided from the flue gas is calculated at 1.323MW when the reboiler duty is 0.3353 MW. However, the project is not sustainable under current market conditions.Item Open Access Application of microbubbles to ozonation for drinking water treatment.(Cranfield University, 2022-11) John, Alexander; Jarvis, Peter; Carra ruiz, Irene; Jefferson, BruceOzonation is a widely used water treatment process that is used to oxidise contaminants as well as disinfect water. Conventional ozone contactors have a large energy requirement and deep tanks to ensure adequate mass transfer. As a result, the delivery of ozone into water is an energy intensive and expensive process. The use of microbubbles in water treatment is a new technology that has been shown to significantly improve gas-liquid contacting processes. Microbubbles have diameters ranging from 1 – 100 µm, whereas conventional bubbles used in typical ozone contactors have diameters ranging from 2 – 6 mm. Due to their small size, microbubbles have a larger interfacial area and a lower rise velocity than conventional bubbles. Therefore, ozone in the gas phase may be transported more efficiently into the liquid phase. Despite the favourable properties of microbubbles, the mechanism by which microbubbles outperform conventional bubbles is not fully understood, with various conflicting interpretations having been presented in the literature. This work is comprised of several direct-comparison studies of microbubble and conventional bubble ozonation systems under identical conditions. Experiments were normalised for both input and effective ozone dose in order to determine a number of critical performance parameters including: hydroxyl radical production, volumetric mass transfer coefficient, ozone self-decomposition, rate and extent of compound removal and bromate formation. Overall, the observed performance enhancement was attributed to an increase in the volumetric mass transfer coefficient through the combination of an increase in bubble specific interfacial area and a decrease in the mass transfer coefficient. When normalised to effective ozone dose, no enhancement in hydroxyl radical production or increase in bromate formation was observed. In addition, the generation of microbubbles results in a distribution of bubbles containing both micro- and nanobubbles. It was concluded that in order to optimise the overall ozonation process, emphasis should be placed on understanding how to manage the size distribution of the microbubble fraction as the risk of residual ozone from nanobubble survival was deemed insignificant. These findings were then applied to the design of microbubble contactors to determine the economic viability of microbubble generation when applied to ozonation at full scale compared with a conventional bubble ozone contactor.Item Open Access Application of suspended ion exchange, in-line coagulation and ceramic membranes for surface water treatment(Cranfield University, 2016-04) Metcalfe, David Christopher; Jarvis, PeterA long term, large scale pilot study was performed to assess the use of a novel process based on suspended ion exchange (SIX®) and in-line coagulation (ILCA®) pretreatment for ceramic membrane filtration (CeraMac®), for treating three variable quality UK surface waters. SIX was shown to remove similar quantities of dissolved organic carbon (DOC) to coagulation for low to moderate DOC source waters. However, during periods of high DOC concentrations and high specific UV absorbance, the removal of organic compounds was reduced. The long term DOC removal data for the SIX process indicated good performance, which was in line with previously reported results from studies using other suspended ion exchange processes. Organic characterisation using liquid chromatography–organic carbon detection (LC-OCD) revealed the differing selectivities of the SIX and ILCA processes, for low and high molecular weight organic fractions respectively. When these processes were used in combination, a broad range of organic compounds were removed, leading to a 50% reduction in DOC concentration in comparison with an existing full scale conventional treatment process. Subsequently, disinfection by-product (DBP) formation was significantly reduced (62% vs. the conventional process) due to the lower DOC concentration, reduced specific reactivity of the residual organic compounds and reduced formation of brominated DBPs. Removal of high molecular weight organic compounds (biopolymers) was shown to be critical for stable operation of ceramic membranes at high flux. Optimised in-line coagulation (ILCA) pretreatment (which flocculated the biopolymers) led to negligible membrane adsorption of organic compounds, as low molecular weight (LMW) fractions (which are recalcitrant to coagulation) were shown not to be retained by the membrane. Due to this, when using optimised ILCA, additional removal of LMW organic fractions by using SIX in combination with ILCA provided no measureable benefit with regards to membrane fouling suppression. Automation of coagulant dosing was achieved for the high SUVA waters tested, using simple feed forward control based on the UV transmittance of the feed water. The application of this automated system led to very low membrane fouling rates (0.24kPa/day), despite highly challenging operating conditions of elevated fluxes (185 L m- 2 h- 1 ) and highly variable feed water dissolved organic carbon concentrations (1-10mg/l).Item Open Access Approaches to maximise the utilisation of residues from thermal conversion of oil palm waste.(Cranfield University, 2020-12) Ukanwa, Kalu Samuel; Patchigolla, Kumar; Sakrabani, RubenPalm oil processing generates enormous volume of waste, which can be used as a feedstock in thermal processing. Subsequently, these can be valuable in the production of activated carbon (AC) and soil amelioration. The production of AC often results in secondary contamination through activating agents. This prompts the necessity for a non-toxic activating agent for high quality production of high adsorptive AC. Therefore this research aims to assess and determine the optimum route for efficient utilisation of biowaste from thermal conversion process of palm oil residues in producing activated carbon and soil amelioration by evaluating the impact of the selected utilisation techniques. In the production process, energy demand and process duration have influence on the efficiency of AC; therefore, an appropriate design configurations and parameter selection are required to achieve an anticipated yield. AC was produced by microwave and conventional techniques through pyrolysis. The feedstock was also used in combustion and the thermal residues were applied in agricultural soil and crop yield relative to application rate was assessed on Habanero chili pepper. Therefore, the requisite to quantify the processes, which include appropriate assessment of the technology and economic performance. The accomplishment of the project overall aim was dependent on the design of a microwave system for efficient biomass pyrolysis. The process also evaluated the microwave interaction with reactors implemented to produce AC from mixed oil palm waste, using Trona ore as an activating agent. The AC was analysed to determine the effectiveness of Trona ore for activation using Fourier infrared spectrometry, Brunauer-Emmett-Teller (BET) analyser and scanning electron microscope. The oil palm waste ash was applied to the soil. The optimum outcome of the microwave assisted technique for combine palm waste (CPW) was obtained at 600 W, BET surface area (SBET) is 980 m²/g compared to 920 m²/g from a conventional technique; total volume (Vtotal) 0.865 cm³/g; mean pore diameter 2.2 nm and AC yield is 42%. Therefore, this study additionally identifies the need for an even distribution of electromagnetic waves within the reactor during activation to ensure uniformity of AC. It also proposes that the design of a composite reactor for an industrial production of AC is necessary to enable heterogeneous waste stream of the process. For ash application, the physiological development and crop yield were measured. The combine maximum yield for both sites were 49 t/ha/first season and 71.8 t/ha/second season, occurred at 8 t/ha treatment plot against the control plot with 1.3 t/ha/first season and 0.7 t/ha/second season. The interaction between oil palm waste ash and soil, improved agronomic efficiency of Habanero chilli pepper by 66-69% and Scoville value by 3.52%. These utilisation routes (AC production and ash to soil) were further integrated for economic and technological benefits using Aspen plus Economy. The processes have 16-17% return on investment for the 8-9 year payback period. This study therefore concluded that thermal residues of oil palm waste are useful in the production of high quality AC and also has rich effect on agricultural soil.Item Open Access Assessing habitat outcomes of floodplain forest restoration: case study at the Ouse Valley Park(Cranfield University, 2016-12) Perez Linde, Natalia; Gill, A. B.The research project for this PhD set out to provide a best practice example of bringing together industry (Hanson Heidelberg Cement Group), a charitable body (The Parks Trust), non-departmental public body (Environment Agency) and academia (Cranfield University). The Parks Trust (landowner) and Hanson (quarry operator) worked together with the vision of creating a new floodplain forest landscape along a 1 km reach of the River Great Ouse following extraction of gravels from the site. It was the first project of its kind in the United Kingdom where planning permission was obtained specifically for the creation of a floodplain forest habitats post quarrying. The aim of the PhD research was to determine appropriate ecological approaches to apply to the assessment and future monitoring of habitat outcomes of a floodplain forest restoration project at a mineral extraction site. A central element of the research was the design of a scientifically justified monitoring programme, with key variables determined being: soil characteristics, water quality, vegetation development, site topography and water table level data. An Adaptive Monitoring Framework (AMF) was chosen to set the proposed monitoring within which was complemented with the hypothesis - The ratio of wet/dry vegetation within the floodplain forest is determined by the site topography and water table level. The hypothesis was tested by analysis of the key variables through fieldwork and existing data sources supplemented with a study of the water table level interaction with two typical floodplain forest tree species (Salix viminalis and Populus trichocarpa x deltoides) in a glasshouse experiment. Findings from the field and experimental research were then used within a spatially based landscape ecology scenario approach to identify the most suitable areas of the study site for specific species planting according to soil-water levels and topography in the floodplain forest. Outputs of this research enhance understanding of the key aspects to consider when assessing floodplain forest re-creation/restoration and enable guidelines and recommendations to be developed for land managers based on a long-term and an adaptive ecological monitoring approach. These management guidelines and recommendations based on a systematic scientific approach applied within the research should be appropriate to other similar restoration projects. The research provides the background evidence on what should be measured to determine the environmental changes of the floodplain forest habitat restoration as it develops towards restoration success.Item Open Access Assessment of occupational exposure to gasoline vapour at petrol stations(Cranfield University, 2016-01) Alyami, Ahmed Rashid; Crump, Derrick; Walton, Christopher; Magan, Naresh; Salama, KhaledPetrol station attendants’ exposure to gasoline vapours while refuelling vehicles has raised health concerns, especially in tropical countries like Saudi Arabia. This is due to the increase of gasoline vaporisation by the high temperatures and related weather conditions. This represents an increase risk of inhaling more vapours than its counterpart temperate countries. Furthermore, exposure during extended working hours (12 hrs shifts), with no vapour recovery system and the handling of gasoline containing a high percentage of volumes of toxic substances (e.g. BTEXs) have not been adequately addressed previously in Saudi Arabia. Therefore, this study was designed and carried out to investigate the validity of this concern by assessing and quantifying full shift exposures to gasoline vapours during the petrol filling process. Different exposure assessment methodologies were employed and evaluated for their suitability. The study assessed the exposures of 41 attendants via passive, active, and direct reading methods at twelve petrol stations with both high and low sales in the Eastern Province of Saudi Arabia. The study was conducted during the winter and summer months to test the seasonal variation of the pattern of exposure. The effects of the quantity of gasoline sold, the locations of the stations, weather variations (e.g. wind speed, temperature, and humidity) were tested. A purpose built mini-weather stations and modified thermometres were utilized to accurately monitor the prevailing weather conditions. Forward-looking infrared (FLIR) thermal image cameras were utilised to visualise the size and movement behaviour of the vapour plumes during petrol refuelling. Furthermore, analytical lab trials were carried out to characterise the gasoline vapour component under different temperatures. These were used to propose a new OEL. The geometric means of the personal passive results for BTEX and MTBE (0.18 ppm, 0.24 ppm, 0.09 ppm, 0.18 ppm, 1.57 ppm, respectively) were found to be relatively higher than those reported previously for Europe and North America. These results are discussed in the context of the impact that such exposure will have on people involved in this industry in petrol stations in Saudi Arabia.Item Open Access The Behaviour of Haloacetic Acids in Distribution Zones in Scotland(Cranfield University, 2014-09) Agori, Georgia; Goslan, EmmaHAAs are the second most prevalent class of DBPs after THMs in chlorinated drinking water and are of concern due to their potential human health risk. Their concentrations in drinking water are regulated by the US Environmental Protection Agency (US EPA) and other regulatory agencies and are currently under consideration by the European Union to be regulated at 80μg/L. However their monitoring in the distribution system is complicated because several parameters influence their formation and speciation. In addition the kinetics of HAAs and their formation and stability remain largely unidentified. The HAAs are not as chemically or biologically stable as THMs in aquatic systems and their stability may impact their measurement. The levels of HAAs within a distribution system may vary seasonally and spatially. Many studies have shown that their concentration in a distribution system can rise as well as fall. The levels of HAAs in the distribution system could be increased in the presence of residual chlorine or due to the decomposition from other DBPs and be decreased by biodegradation or hydrolysis and abiotic degradation. However biodegradation is likely the major loss process occurring in drinking water distribution systems. This study provides an interesting picture of HAAs levels in distribution water in Scotland. A statistical analysis has been carried out using measurements of HAAs concentrations and other water quality parameters from 298 Scottish water distribution zones in to investigate the relative occurrence and speciation of HAAs, and determine their behaviour in water distribution systems, monitoring differences between zones. This study also allowed evaluation of the impact of seasons on HAAs concentrations and speciation in Scotland’s distribution zones. The results obtained show that the median concentrations of HAA5 is 11.5μg/L. The average HAA5 in distribution systems were about 50% lower than total trihalomethanes (THMs). In 0.7% of the zones under study, the average HAA5 concentration exceeds 60μg/L. These zones are supplied by small WTWs (<3,300 people) and are using chlorination. HAAs concentrations varied according to their water source and the disinfection strategy used. Low HAA5 levels (the median was <5.3 μg/L) were observed in the groundwater systems and higher levels were observed in the surface water systems (the median was 12.4 μg/L). The chloraminated waters have lower HAA5 and THMs levels compared to chlorinated waters, but the difference is not that pronounced. Generally chlorinated HAAs dominated in the waters of the distribution under study. The dominant species were trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA). DCAA and TCAA were present at almost in equal levels in chlorinated waters but DCAA was the dominant group detected when using chloramination. Furthermore seasonal variations of the concentrations of different HAAs species were observed. The concentrations of HAA5 were higher in summer and autumn and lower in winter and spring but the difference was not statistically significant. THMs has a similar seasonal pattern but with a more pronounced variation than HAAs. The median data show almost no seasonal variation for dichlorinated HAAs. However the seasonal variation of TCAA is more pronounced and higher concentrations were detected during summer and autumn.When the data sets from all distribution zones were combined there was a strong correlation between total THMs and HAA5, total THMs and TCAA and HAA5 and total organic carbon (TOC). The spatial variability of HAAs and THMs concentrations in two distribution zones using different disinfection strategies (chloramination and chlorination) was also studied. There has previously been no full scale study in the UK with the attempt to link the behaviour to distribution factors such as microbial water quality or distribution mains material. In both systems THMs generally presented stable and increasing concentration profiles along the system, whereas HAAs increased and decreased, a phenomenon probably related to biodegradation. There is also evidence that abiotic reduction of HAAs is possible in the iron pipes for the chlorinated distribution system. Using flow cytometry we observed generally higher levels of total and intact cells in the chloraminated distribution zone. Thus large numbers of dead cells can contribute to HAAs formation.Item Open Access The behaviour of metal(oid)s contaminants in woody biomass during advanced thermal conversion processes.(Cranfield University, 2019-05) Al-Badri, Shurooq Badri; Wagland, Stuart; Jiang, YingA remarkable proportion (about 64%) of renewable biomass energy is produced from woody biomass (wood and its wastes). However, waste wood (WW) often exhibits a high level of chemical contaminants, likely due to the presence of metal(loid) elements in preservatives, paintings, coatings, and other related activities. By thermally treating WW, the metal(loid)s will end up in the bottom ash and/or be emitted into the atmosphere, causing severe environmental concerns and technical damages (e.g. slagging and corrosion). Thus, it is necessary to understand the behaviour of metal(loid)s during the woody biomass thermal conversion process, specifically gasification and pyrolysis. While a great deal of knowledge is available on this matter, there is still uncertainty surrounding the identification and characterisation of metal(loid) elements in relation to woody biomass utilisation, as well as the influences of reaction atmosphere composition in terms of interactions and interferences. In addition to that, knowledge is needed on partitioning profiles of the key metal(loid) elements during the gasification and pyrolysis of WW in order to evaluate the emission potential of these elements. This thesis firstly provides a highly informative dataset that contains comprehensive details about the characterisation and elemental composition of key metal(loid) elements (As, B, Co, Cr, Cu, Fe, Ni, Pb, Mn, Hg and Ti) that are regularly present in woody biomass. Moreover, chemical equilibrium calculations were performed to predict elemental phase transformation and speciation formation under given gasification and pyrolysis operation conditions. Among the results, it was found that Ni-As interactions form the dominant species As₂Ni₅ and As₈Ni₁₁, which increase the solid-gaseous phase transformation of As. In addition, the Ca-Cr interaction forms C₃Cr₇; meanwhile, the absence of Ca creates instability in the Cr phase transformation due to the generation of the species Cr₂Na₂O₄. Subsequently, a set of experiments were conducted using a TGA analyser with different heating rates to understand the thermal behaviour of woody biomass and define the operational conditions of the pyrolysis process. Tube furnace experiments were also conducted to investigate the distributions of Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Na, Mn, Mo, Ni, Pb, Si, Ti, V, and, Zn during the operation of pyrolysis. Experimental results indicated that Cd and Hg are exceedingly volatile elements, whereas Al, Co, Cr, Cu Fe, Mo, Ni, Si, Ti, and V are non-volatile elements. The elements As, Mn, Pb, and Zn exhibited differences in partitioning across all experiments. Importantly, this study provides unique insight into the behaviour of As in terms of As-Ni interaction. That is, the presence of Ni should be regarded in combination with its associated concentration profile. Finally, the experimental data and the calculation results are complementary rather than competitive. Overall, the experimental results are within acceptable validation limits.Item Open Access A bioinformatics and genotyping approach exploring personalised nutrition.(Cranfield University, 2021-11) Molitor, Corentin; Mohareb, Fady R.; Thompson, Andrew J.Personalised nutrition is at its early stages but shows the potential of improving the health of the general population, at a time when diabetes and obesity are becoming worldwide epidemics. However, it will need to be based on rigorous scientific research, as well as being accompanied by public policies and ethical considerations. Research is making great progress towards the understanding of the impact of genetics on complex diseases, which involve hundreds, or thousands, of variants, each having varying effect on the disease. Personalised medicine aims at harnessing this genetic information to tailor prevention and treatment according to each individual. Unfortunately, the links between the genotype and the phenotype are not yet fully understood. And while the content of publicly available genetic databases is exponentially growing, they are often using different formats and means of access, making it difficult to get complete information. Moreover, evaluating the genetic predisposition of an individual to a disease is not straightforward, and while Polygenic Risk Score models can help in this regard, they are often only based on common variants, which might lead to misevaluation of the risk for rare- variants carriers. In this thesis will be presented (i) VarGen, an R package to merge information from different genetic databases, which has the potential to infer new variant- disease relationships. (ii) a new method to improve Polygenic Risk Score models, which includes variants obtained from VarGen on top of the common variants from standard polygenic analyses. (iii) the results of a microRNA differential expression analysis, aiming at identifying the impact of microRNAs, on the development of severe Hypoxic-Ischemic Encephalopathy in new-borns.Item Open Access Biological FOG degradation: development of a standardised bioadditive protocol.(Cranfield University, 2018-11) Gurd, Caroline; Villa, Raffaella; Jefferson, BruceFSE, wastewater, Gerber, COD:N, bioaddition, bioremediation, Fat, oil and grease (FOG) rich effluents from commercial food service establishments (FSEs) have been identified as major contributors to sewer blockages. Under UK Legislation, all FSE kitchens should be fitted with an ‘effective mean of grease removal’. Currently, microbial bioadditives, one of the preferred FOG management options, do not have an industry-agreed testing methodology to prove their ‘effectiveness’. The primary goal of this research was to generate the scientific knowledge underpinning a testing protocol for FOG- degrading bioadditives. Environmental conditions prevalent in FSE wastewater streams were identified in a characterisation of effluents from three catering outlets on Cranfield University campus and used as a basis for design of synthetic culture media for testing bacterial degradation. To address interferences caused by high levels of surfactants in FSE wastewater, a novel FOG quantification method, based on the Gerber method used in the milk industry, was developed for the protocol. This method is efficient at recovering emulsified FOG, and also allows emulsified and free fractions to be quantified separately. Microbial utilisation of different wastewater components was evaluated in batch degradation trials using a model bacterium, Bacillus licheniformis NCIMB 9375, and different synthetic wastewater compositions. The source of readily available carbon showed great influence on FOG-degradation response. FOG uptake was also influenced strongly by the carbon to nitrogen ratio in the media composition, with removal rate constants decreasing by over an order of magnitude from 0.0285 to 0.0026 h-1 when initial COD:N increased from 33:1 to 147:1. A cost-benefit analysis of the currently available FOG management solutions suggest that bioadditives, as a standalone solution, are the best option in terms of total cost and space requirements, followed by bioadditives used with grease separators. Combining physical and biological treatments can enhance the individual performance of both technologies and allow energy recovery from physically separated FOG.