Staff publications (SWEE)

Permanent URI for this collection

https://dspace.lib.cranfield.ac.uk/handle/1826/8743

Browse

Now showing 1 - 20 of 3114

Open Access
Enhancing methane production by adding Fe3+ in mesophilic anaerobic digestion of cheese waste
(EDP Sciences, 2025-03-07) Sugiarto, Yusron; Pamungkas, Bintang; Wibisono, Yusuf; Izza, Ni’matul; Mufidah, Elya; Maharsih, Inggit Kresna; Nugroho, Wahyunanto Agung; Sofi’i, Imam; Zhu, Mingming
The advancements in cheese production technology have resulted in increased waste generation, especially in the form of liquid byproducts left over after the milk clotting process. This research examines the possibility of using cheese waste to produce methane (CH4) through mesophilic anaerobic digestion and investigates how adding iron (Fe) can improve CH4. Field experiments were conducted to evaluate the effects of varying concentrations of cheese waste (0–33.33 g/L) and FeCl3 (0–3.0 g/L) on CH4 yield. Results revealed that the addition of 2 g/L FeCl3 achieved the highest cumulative CH4 yield and production rate, with increases of 68% and 65% over the control, respectively. The study also monitored pH levels and found that the best treatment maintained a near-neutral pH of 6.79 by day 50, which is important for sustaining effective microbial activity. This study highlights the potential of incorporating Fe supplementation to optimize CH4 yields from cheese waste and other organic substrates, contributing to more sustainable and efficient renewable energy production.
Open Access
Wave interaction with multiple floating elastic plates with arbitrary constraints near a sloping beach
(AIP Publishing, 2025-03-01) Yang, Yifeng; Huang, Luofeng; Meylan, Michael H.
The problem of wave interaction with multiple elastic plates floating near a sloping beach is considered, particularly resembling the case of a floating solar farm near a coast. The linearized shallow water theory is adopted to describe the motion of fluid. The Kirchhoff–Love plate theory is used to model the elastic plates. A highly efficient domain decomposition approach is applied to derive the solution. Particularly, the eigenfunction expansions are employed to establish the velocity potential in free surface fluid domains, while the Green function method is used to construct the velocity potential of the fluid domain covered by floating elastic plates. This approach can significantly reduce the number of unknowns in the velocity potential, especially when a large number of plates are involved. Extensive results and discussions are provided for the wave run-up on the beach, maximum deflection, and principal strain on the elastic plates. In particular, based on a wide space approximated solution, the oscillatory behaviour of the wave run-up vs the incident wavenumber is analysed, along with the corresponding physical mechanisms. Furthermore, apart from the frequency-domain results, time-domain analyses are also conducted based on a Fourier transform approach. Two different types of incident impulses are considered to interact with floating elastic plates near a beach, namely a Gaussian wave packet and a storm-type incident wave.
Open Access
A very simple flexible tandem dye-sensitized solar cell
(Springer, 2024-12-01) Alessa, Hussain; Wijayantha, K. G. Upul
Dye-sensitized solar cells (DSSCs) have been proposed as the most important third generation photovoltaic devices owing to their low fabrication cost, design flexibility, having low hazard to the environment and ease of construction. Tandem DSSCs (T-DSSC) were said to possess properties of its sensitized photoanode and sensitized photocathode in terms of the power conversion efficiency (PCE) parameters. With less studies on the fabrication of simple a flexible tandem DSSC, this work aims at filling this gap as well as showing the influence of one of the main factors that affect the performance of such a device. In this paper, TiO2 and NiO layers were prepared by blading method, sensitized separately, then sandwiched together. The fabricated device produced short circuit current, open circuit voltage and power conversion efficiency of 0.138 mA.cm−2, 0.942 V and 0.063%, respectively. This simple T-DSSC produced a high photovoltage and showed that the photocurrent produced by each photoelectrode should be identical. This match is to overcome the possible hump in the device performance.
Open Access
Effect of operation time on the performance and accuracy of the Condor reflectometer
(TIB Open Publishing, 2024-07-24) Karim, Mounia; Sansom, Christopher; Hussaini, Zaharaddeen; Almond, Heather; Fernández-García, Aránzazu; Sutter, Florian; Wiesinger, Florian; Wette, Johannes; King, Peter
This paper evaluates the potential effect that operation lifetime could have on the accuracy and reproducibility of the Condor reflectometer. For this purpose, three Condors with different operation lifetimes have been used and compared in this study. In addition to the device’s operation lifetimes, reproducibility and the repeatability of the measurements have also been evaluated. Silvered glass mirrors at different states have been used, e.g., clean, soiled and eroded in order to evaluate the effect of the surface properties on the difference reported using different devices. The obtained results have shown that the difference in specular reflectance reported by the three different Condors is more noticeable in case of soiled and eroded glass mirrors compared to clean sample. This could be linked to the surface roughness more than to the years of operation of the device itself.
Open Access
Numerical simulation of subfields in a multi-tower concentrated solar field
(TIB Open Publishing, 2024-07-24) Hussaini, Zaharaddeen Ali; Sansom, Chris; King, Peter; Karim, Mounia
The research introduces an innovative approach to enhancing the efficiency of Multi-tower Concentrated Solar Power (CSP) through a configuration termed Auxiliary Tower with Subfield (ATS). ATS introduces an auxiliary tower and creates a subfield by adding heliostats near its position, aiming to optimize the solar field's optical efficiency and offer modular decentralized power output. ATS configuration employs existing field configurations to pinpoint inefficiencies where an additional tower can be installed, and heliostats are systematically added to the subfields through numerical optimization using various design variables. Although the inclusion of a subfield in the ATS configuration enhances energy output, it does not always offset the additional costs of the auxiliary tower, receiver, and extra heliostats, in small fields. However, when applied to larger fields, starting from 200MWth, ATS begins to provide a lower Levelized Cost of Heat (LCOH) compared to optimized conventional thermal fields, demonstrating its potential applicability and efficiency in larger-scale CSP setups. Applying ATS to a 120 MWth Gemasolar-like plant further confirms its advantages, with 160 MWth emerging as the optimal enhancement point that boosted efficiency while lowering LCOH. ATS shows promise as an efficient, modular approach to scaling up power tower system.
Open Access
Iron and nitrogen co-doping biochar for simultaneous and efficient adsorption of oxytetracycline and norfloxacin from wastewater
(Elsevier, 2025-04-01) Cheng, Xiaoxue; Jiang, Ding; Zhu, Weiyi; Xu, Huan; Ling, Qifan; Yang, Jingwen; Wang, Xinyu; Zhang, Kexin; Zheng, Xiaolong; He, Sirong; Cao, Bin; Wagland, Stuart; Wang, Shuang
The global proliferation of antimicrobial resistance (AMR) poses a critical challenge to environmental and public health, driven by excessive antibiotic release from medical, agricultural, and aquaculture activities. This study investigates the synthesis and application of Fe/N-doped biochar derived from Enteromorpha clathrata (EC) for the removal of oxytetracycline (OTC) and norfloxacin (NOR) from water. The biochar, synthesized via pyrolysis and NaOH activation, was characterized by BET, SEM, and XPS analyses, revealing a porous structure with enriched functional groups. The EC-derived biochar demonstrated high adsorption capacities for OTC (625.325 mg·g⁻1) and NOR (487.379 mg·g⁻1) under neutral pH conditions, with adsorption following Langmuir and pseudo-second-order models, indicative of monolayer chemisorption. The biochar also exhibited excellent reusability, supporting practical applications. The strong interactions between the FeN4 active sites and the antibiotics were quantified through DFT calculations, showing binding energies of −394.91 kcal/mol for NOR and −398.10 kcal/mol for OTC, highlighting the important role of FeN4 in facilitating efficient adsorption. Additionally, density of states (DOS) analysis revealed that formation of Fe-N/O chemical bonds was confirmed through the hybridization of Fe 3d orbitals with N/O 2p orbitals. Overall, Fe/N-rich biochar contributes to its potential for practical applications in antibiotic removal from aqueous systems.
Open Access
Temperature-dependent electrosynthesis of PEDOT:PSS: enhanced Na+ transfer targeting high-performance Na-ion batteries
(Elsevier, 2025-04-01) Santos, Daniel R.; Zeferino, Jorge F.; Viana, Ana S.; Wijayantha, K. G. Upul; Lobato, Killian; Correia, Jorge P.
Poly(3,4-ethylenedioxythiophene):Poly(sodium 4-styrenesulfonate) (PEDOT:PSS) is a versatile conducting polymer with physicochemical properties favourable for energy storage applications, such as chemical and mechanic stability and flexibility. However, the temperature at which the polymer is synthesised can significantly influence its properties. In this study, a detailed investigation of the effect of temperature on the electroactivity, morphology, optical properties, and ionic/solvent transport during the redox conversion of potentiostatically and galvanostatically synthesised films was conducted. Electrochemical data, supported by ellipsometry, atomic force microscopy, microgravimetry, and probe beam deflection measurements, revealed that films synthesised at lower temperatures (0 °C) were more compact compared to those synthesised at higher temperatures (40 °C). Films synthesised at 0 °C also exhibited near-ideal reversibility, with a QO/QR ratio of ca. 1. Importantly, the 0 °C films showed a strong pseudocationic doping behaviour, characterised by predominant sodium ion exchange during redox processes. In contrast, films synthesised at 40 °C exhibited mixed ion participation (both sodium and perchlorate), which could negatively impact the performance of electrode material in battery applications. This study demonstrates the potential of PEDOT:PSS as a versatile material for sodium ion cathodes, with properties that can be finely tuned through the synthesis temperature, yielding more compact ion-storage films at lower temperatures.
Open Access
Spatial sensitivity of river flooding to changes in climate and land cover through explainable AI
(American Geophysical Union (AGU), 2024-05-01) Slater, Louise; Coxon, Gemma; Brunner, Manuela; McMillan, Hilary; Yu, Le; Zheng, Yanchen; Khouakhi, Abdou; Moulds, Simon; Berghuijs, Wouter
Explaining the spatially variable impacts of flood‐generating mechanisms is a longstanding challenge in hydrology, with increasing and decreasing temporal flood trends often found in close regional proximity. Here, we develop a machine learning‐informed approach to unravel the drivers of seasonal flood magnitude and explain the spatial variability of their effects in a temperate climate. We employ 11 observed meteorological and land cover (LC) time series variables alongside 8 static catchment attributes to model flood magnitude in 1,268 catchments across Great Britain over four decades. We then perform a sensitivity analysis to assess how a 10% increase in precipitation, a 1°C rise in air temperature, or a 10 percentage point increase in urban or forest LC may affect flood magnitude in catchments with varying characteristics. Our simulations show that increasing precipitation and urbanization both tend to amplify flood magnitude significantly more in catchments with high baseflow contribution and low runoff ratio, which tend to have lower values of specific discharge on average. In contrast, rising air temperature (in the absence of changing precipitation) decreases flood magnitudes, with the largest effects in dry catchments with low baseflow index. Afforestation also tends to decrease floods more in catchments with low groundwater contribution, and in dry catchments in the summer. Our approach may be used to further disentangle the joint effects of multiple flood drivers in individual catchments.
Open Access
Floating solar wireless power transfer system for electric ships: design and laboratory tests
(Elsevier, 2025-05-15) Ibrahim, Khalifa Aliyu; Maréchal, Timothé Le; Luk, Patrick; Qin, Qing; Huang, Luofeng; Xie, Ying; Verdin, Patrick; Luo, Zhenhua
The maritime industry is under increasing pressure to decarbonise, presenting an important pathway of transforming the power systems from conventional marine fuels to electric-based. This study proposes an innovative solution to support maritime decarbonisation through the integration of a floating solar clean energy harnessing and wireless power transfer (WPT) technology for electric vessels. The paper presents the design and experimental tests of the integrated system specifically, based on a model of an electric yacht. This study provides an in-depth analysis of application of floating solar to provides an off-grid wireless power transfer system that can scale for larger vessels such as ferries. The off-grid modularity proposed enables scalable, flexible, and sustainable energy delivery for maritime applications and decarbonisation with specific attention to challenges in WPT alignment and environmental condition. Simulations using ANSYS Maxwell were performed to model the magnetic field interactions and ascertain the optimal power transfer efficiency. Subsequently, a reduced-scale prototype system was designed, built and tested in a wave tank. The experimental results demonstrated efficient wireless charging with an average efficiency of 82 %, and the docking system proved effective in maintaining alignment even when the ship has wave-induced motions. The findings support the feasibility of using floating solar WPT systems for maritime vessels and pave the way to larger-scale studies.
Open Access
Hyperspectral imaging for phenotyping plant drought stress and nitrogen interactions using multivariate modeling and machine learning techniques in wheat
(MDPI AG, 2024-09-17) Okyere, Frank Gyan; Cudjoe, Daniel Kingsley; Virlet, Nicolas; Castle, March; Riche, Andrew Bernard; Greche, Latifa; Mohareb, Fady; Simms, Daniel; Mhada, Manal; Hawkesford, Malcolm John
Accurate detection of drought stress in plants is essential for water use efficiency and agricultural output. Hyperspectral imaging (HSI) provides a non-invasive method in plant phenotyping, allowing the long-term monitoring of plant health due to sensitivity to subtle changes in leaf constituents. The broad spectral range of HSI enables the development of different vegetation indices (VIs) to analyze plant trait responses to multiple stresses, such as the combination of nutrient and drought stresses. However, known VIs may underperform when subjected to multiple stresses. This study presents new VIs in tandem with machine learning models to identify drought stress in wheat plants under varying nitrogen (N) levels. A pot wheat experiment was set up in the glasshouse with four treatments: well-watered high-N (WWHN), well-watered low-N (WWLN), drought-stress high-N (DSHN) and drought-stress low-N (DSLN). In addition to ensuring that plants were watered according to the experiment design, photosynthetic rate (Pn) and stomatal conductance (gs) (which are used to assess plant drought stress) were taken regularly, serving as the ground truth data for this study. The proposed VIs, together with known VIs, were used to train three classification models: support vector machines (SVM), random forest (RF), and deep neural networks (DNN) to classify plants based on their drought status. The proposed VIs achieved more than 0.94 accuracy across all models, and their performance further increased when combined with known VIs. The combined VIs were used to train three regression models to predict the stomatal conductance and photosynthetic rates of plants. The random forest regression model performed best, suggesting that it could be used as a stand-alone tool to forecast gs and Pn and track drought stress in wheat. This study shows that combining hyperspectral data with machine learning can effectively monitor and predict drought stress in crops, especially in varying nitrogen conditions.
Open Access
Understanding of probiotic origin antimicrobial peptides: a sustainable approach ensuring food safety
(Springer, 2024-09-19) Bisht, Vishakha; Das, Biki; Hussain, Ajmal; Kumar, Vinod; Navani, Naveen Kumar
The practice of preserving and adding value to food dates back to over 10,000 BCE, when unintentional microbial-driven chemical reactions imparted flavor and extended the shelf life of fermented foods. The process evolved, and with the urbanization of society, significant shifts in dietary habits emerged, accompanied by sporadic food poisoning incidents. The repercussions of the COVID-19 pandemic have intensified the search for antibiotic alternatives owing to the rise in antibiotic-resistant pathogens, emphasizing the exploration of probiotic-origin antimicrobial peptides to alleviate human microbiome collateral damage. Often termed 'molecular knives', these peptides outstand as potent antimicrobials due to their compatibility with innate microflora, amenability to bioengineering, target specificity, versatility and rapidity in molecular level mode of action. This review centres on bacteriocins sourced from lactic acid bacteria found in ethnic fermented foods, accentuating their desirable attributes, technological applications as nanobiotics and potential future applications in the modern context of ensuring food safety.
Open Access
Real-time CO2 production monitoring in stored oats as an indicator of type A trichothecenes and ochratoxin A contamination under simulated environmental conditions
(MDPI AG, 2025-03-11) Oluwakayode, Abimbola; Sulyok, Michael; Berthiller, Franz; Verheecke-Vaessen, Carol; Krska, Rudolf; Medina, Angel
Grain industries are interested in an integrated approach to in-silo grain quality and safety management using carbon dioxide (CO2) measurement with temperature and moisture monitoring. Our study investigates if CO2 production could predict mycotoxin production (T-2 toxin, HT-2 toxin, its glucoside, and ochratoxin A (OTA)) and identify storage conditions exceeding legislative limits in stored oats for the first time. The influence of water activity (aw) levels (0.70–0.95 aw), temperature (15 and 20 °C), and storage duration on (a) Fusarium populations, (b) CO2 respiration rates (RRs), and (c) mycotoxin concentrations in stored oats was examined. One hundred and twenty samples were analysed for multiple mycotoxins by LC-MS/MS. Substantial differences were found in the RRs of oats at ≥0.90 aw at both temperatures. A moderate positive correlation between CO2 and mycotoxins was noticed and mycotoxins exceeded their limits at ≥0.90 aw (22% moisture content) when RR ≥ 25 µg CO2 kg−1 h−1. This knowledge forms the basis for developing decision support systems for improving oats’ storage management.
Open Access
Putting numbers to a metaphor: a Bayesian Belief Network with which to infer soil quality and health
(Elsevier BV, 2025-07) Hassall, Kirsty L.; Zawadzka, Joanna; Milne, Alice E.; Corstanje, Ronald; Harris, James A.; Dailey, A Gordon; Keith, Aidan M.; Glendining, Margaret J.; McGrath, Stephen P.; Todman, Lindsay C.; Alexander, Paul; Arnold, Philippa; Bennett, Amanda J.; Bhogal, Anne; Clark, Joanna M.; Crotty, Felicity V.; Horrocks, Claire; Noble, Nicola; Rees, Robert; Shepherd, Matthew; Stockdale, Elizabeth A.; Tipping, Edward W.; Whitmore, Andrew P.
Soil Quality or Soil Health are terms adopted by the scientific community as metaphors for the effects of differing land management practices on the properties and functions of soil. Because they are metaphors, consistent quantitative definitions are lacking. We present here an approach based on expert elicitation in the field of soil function and management that offers a universal way of putting numbers to the metaphor. Like humans, soils differ and so do the ways in which they are understood to become unhealthy. Long-term experiments such as the Broadbalk Wheat experiment at Rothamsted provide unparalled sources of data with which to investigate the state and changes of soil quality and health that have developed from known management over timescales of one hundred years or more. Similarly, large-scale datasets such as the National Soils Inventory and Countryside Survey provide rich resources to explore the geographical variability of soil quality and health in different places against a background of different observed management practices. We structure experts’ views of the extent to which soil delivers the functions expected of it within Bayesian Belief Networks anchored by measurable properties of soil. With these networks, we infer the likely state of soil (i) on Broadbalk, (ii) at locations throughout England & Wales as well as inferring (iii) the most straightforward ways of improving soil quality and health at the locations in (ii). Our methodology has general applicability and could be deployed elsewhere or in other disciplines.
Open Access
Stakeholder perceptions of drought resilience using government drought compensation in Thailand
(Elsevier, 2025-04-15) Chengot, Rishma; Goodwin, Daniel; Tanguy, Maliko; Armitage, Rachael; Pardthaisong, Liwa; Jha, Srinidhi; Holman, Ian; Rey Vicario, Dolores; Visessri, Supattra; Ekkawatpanit, Chaiwat; Hannaford, Jamie
In the context of escalating climate challenges in Southeast Asia, this study investigates the dynamics of disaster budget allocation in Thailand and examines farmers' perceptions of drought compensation, focusing on the Ping catchment situated in the Northwest of the country. The main objective of the study was to gauge stakeholders' awareness and views on government drought compensation and evaluate its effectiveness. Using government budget data, drought indicators, and a comprehensive survey in Chiang Mai and Tak provinces, the study explores correlations between budget allocation, drought indicators, and farmers' experiences. A correlation analysis unveils stronger links between compensation and Vegetation Condition Index (VCI) as compared to Drought Severity Index (DSI), with regional variations and the impact of irrigation practices. Compensation shows positive correlations with drought severity, suggesting support to farmers occurs when they suffer severe crop damage. We investigate drought occurrences and their impacts along with farmer's awareness and experiences of drought compensation schemes to uncover disparities in awareness, application rates, and satisfaction levels, providing insights into farmers' views on compensation effectiveness. The study concludes by proposing policy adjustments, tailored regional approaches, and feedback mechanisms to enhance the effectiveness of drought compensation strategies. Despite limitations in sample size and potential biases, this study contributes valuable insights into the complex dynamics of disaster budget allocation, drought compensation, and farmers' perspectives in Thailand, laying a foundation for refining policies and fostering sustainable agricultural practices amidst increasing climate challenges.
Open Access
Supplementation strategies to control propionic acid accumulation resulting from ammonia inhibition in dry anaerobic digestion: osmoprotectants, activated carbon and trace elements
(Elsevier, 2025-04-01) Rocamora, Ildefonso; Wagland, Stuart T.; Hassard, Francis; Villa, Raffaella; Peces, Miriam; Fotidis, Ioannis A.; Simpson, Edmon W.; Fernández, Oliver; Bajón Fernández, Yadira
Propionic acid accumulation in anaerobic digestion is a common sign of inhibition at high ammonia levels. To mitigate accumulation three supplementations were tested: osmoprotectants, trace elements and activated carbon. Activated carbon and osmoprotectants (MgCl2) achieved a 28 % increase in methane yield and a 3-fold reduction in hydrogen partial pressure compared with the control. Trace elements supplementation increased methane formation by 18 % without preventing instability. No supplementation avoided propionic accumulation, although MgCl2 delayed it. Activated carbon and MgCl2 supported proliferation of strict hydrogenotrophs, increasing microbial redundance with expected positive impacts on process resilience. Evidence beyond previous studies on the role of retention time as a control parameter of versatile archaea's methanogenic pathway is also provided. As retention time is reduced, syntrophic acetate oxidising bacteria are washed out of the system, likely resulting from an increase in their doubling time with inhibitors accumulation, preventing hydrogenotrophic methanogenesis and supporting previous observations of Methanosarcina being forced to conduct acetoclastic methanogenesis. Longer retention times to accommodate longer doubling times or alleviation of inhibition with activated carbon and MgCl2 supported retention of syntrophic acetate oxidising bacteria, enabling strict hydrogenotrophic archaea to proliferate. These supplementations would allow operation of industrial scale ADs at shorter retention times and higher throughputs. Results suggest that osmoprotectants and activated carbon addition were linked to a reduction in archaea's osmotic pressure and enhanced direct interspecies transfer, respectively, leading to increased methane formation despite propionic levels.
Open Access
Molecular mechanistic insights towards aggregation of nano-biochar moderated by aromatic components in dissolved organic matter
(Elsevier, 2025-03-01) Zhou, Zheng; Lu, Meng; Huang, Yu; Zhao, Changping; Wang, Yafeng; Pidou, Marc; Wu, Min; Chen, Quan; Jeffrey, Paul; Pan, Bo
Nano-biochar (NBC) is a promising tool for sustainable remediation of contaminants in aquatic environments. However, the presence of ubiquitous ions and dissolved organic matter (DOM) can impact NBC aggregation, resulting in reduced application efficacy and potential ecological risks. Understanding and regulating NBC aggregation offers valuable insights for its deployment. This study integrated batch aggregation experiments, theoretical models, Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS), and density functional theory (DFT) calculations to explore the behaviors and mechanisms of NBC aggregation with coexisting ions and model DOM. NBC aggregation kinetics followed the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory in both NBC-ions and NBC-ions-fulvic acid (FA) solutions, indicating that the aggregation process is controlled by Van der Waals forces and electrostatic repulsion. Mono/di-valent electrolytes promoted NBC aggregation, whereas FA moderated it, with higher molecular weight FA fractions exhibiting superior performance. Three-dimensional excitation-emission (3D-EEM) fluorescence spectra and Parallel factor analysis (PARAFAC) analyses revealed that HA-like substances, followed by FA-like substances, can form a complex with ions, thereby moderating NBC aggregation. FTICR-MS scans identified lignin substances with aromatic structures as key components that effectively reduce the promoted NBC aggregation with coexisting mono/di-valent electrolytes. DFT calculations confirmed that the aromatic structures in FA spontaneously form complexes with electrolytes, thereby potentially regulating NBC aggregation. This research highlights potential strategies for regulating NBC applications and offers insights into the behavior of nanoparticles in aquatic environments.
Open Access
The temperature dependence of greenhouse gas production from Central African savannah soils
(Elsevier, 2025-03-01) Girkin, Nicholas T.; Cooper, Hannah V.; Johnston, Alice S.; Ledger, Martha; Niamba, G. R. Mouanda; Vane, Christopher H.; Moss-Hayes, Vicky; Crabtree, Dafydd; Dargie, Greta C.; Vasquez, Saul; Bocko, Yannick; Mampouya Wenina, Emmanuel; Mbemba, Mackline; Boom, Arnoud; Ifo, Suspense Averti; Lewis, Simon L.; Sjögersten, Sofie
Savannahs cover 20 % of the global land surface, but there have been few studies of greenhouse gas (GHG) dynamics from savannah soils. Here, we assess potential turnover of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from surface (0–10 cm) and subsurface (20–30 cm) soils from two contrasting tropical savannah sites in the Republic of Congo, Central Africa, under dry (40 % water-filled-pore-space, WFPS) and wet (70 % WFPS) conditions. Under baseline conditions (25 °C), we found soils were sources of CO2 and N2O, but a sink for CH4. Assessment of the temperature response of GHG fluxes between 20 and 35 °C revealed variable temperature dependences. That is, CO2 fluxes showed a strong temperature response, whereas the temperature response of N2O fluxes was only significant under dry conditions, and no significant temperature response of CH4 fluxes was observed. The temperature quotient (Q10) of soil respiration increased from 1.58 ± 0.004 to 1.92 ± 0.006 at sites with lower soil organic carbon contents. The relative increase in N2O with CO2 fluxes across temperatures was significantly influenced by moisture conditions at both sites. No temperature or soil moisture response was observed for CH4 fluxes, collectively implying divergent GHG responses to changing climatic conditions. Using Rock-Eval pyrolysis we assessed the organic chemistry of all soil types, which indicated contrasting degrees of stability of carbon sources between sites and with depth which, alongside significant differences in a range of other soil parameters (including organic matter content, total carbon, total nitrogen, electrical conductivity, and pH), may account for site-specific differences in baseline GHG emissions. Taken together, our results are amongst the first measures of GHG temperature sensitivity of tropical savannah soils, and demonstrate that soil CO2 emissions are more sensitive to warming and changes in moisture than the emissions of other GHGs, although relatively low compared to responses reported for soils from other tropical ecosystems. This implies that GHG fluxes form savannah soils in the region may be at least partially resilient to climate-induced soil warming compared to other ecosystems.
Open Access
Xylitol production from brewer’s spent grain via Pichia fermentans fermentation: optimization, scaling, and isolation
(Wiley, 2025-03-06) Mathur, Srishti; Kumar, Dinesh; Kumar, Vinod; Verma, Rachna; Lalhlenmawia, H.; Kumar, Deepak
The primary aim of this study was to investigate the novel application of brewer’s spent grain (BSG), a waste byproduct from the brewing industry, as sustainable and cost‐effective feedstock for xylitol production using the yeast Pichia fermentans. The process encompassed fermentation optimization, scale‐up, and then downstream processing to produce xylitol. Shake flask fermentation was employed to determine optimal conditions, evaluating key parameters including inoculum concentration (12.5%), feedstock (50%), pH (7.0), temperature (30°C), incubation time (96 h), and agitation speed (150 RPM) with a maximum xylitol production of 32.74 g/L. The yield of xylitol increased to 34.57 g/L by scaling up in an 8‐L bioreactor within an incubation time of 72 h. Downstream processing, including centrifugation, charcoal treatment, and ethanol purification was performed successfully, recovering xylitol crystals with a purity of 85.90%. Characterization using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and high‐performance liquid chromatography (HPLC) confirmed the purity and composition of crystals. This research highlights the economic and environmental advantages of utilizing BSG for xylitol production, offering a sustainable route over conventional substrates.
Open Access
Sustainable management of riverine N2O emission baselines
(Oxford University Press (OUP), 2025-02-01) Wang, Shuo; Zhi, Wei; Li, Shengjie; Lyu, Tao; Ji, Guodong
The riverine N2O fluxes are assumed to linearly increase with nitrate loading. However, this linear relationship with a uniform EF5r is poorly constrained, which impedes the N2O estimation and mitigation. Our meta-analysis discovered a universal N2O emission baseline (EF5r = k/[NO3−], k = 0.02) for natural rivers. Anthropogenic impacts caused an overall increase in baselines and the emergence of hotspots, which constitute two typical patterns of anthropogenic sources. The k values of agricultural and urban rivers increased to 0.09 and 0.05, respectively, with 11% and 14% of points becoming N2O hotspots. Priority control of organic and NH4+ pollution could eliminate hotspots and reduce emissions by 51.6% and 63.7%, respectively. Further restoration of baseline emissions on nitrate removal is a long-term challenge considering population growth and declining unit benefits (ΔN-N2O/N-NO3−). The discovery of EF lines emphasized the importance of targeting hotspots and managing baseline emissions sustainably to balance social and environmental benefits.
Open Access
Resilience to climate change by biocontrol yeasts against Ochratoxin A production in Robusta coffee
(MDPI, 2025-03-01) López-Rodríguez, Claudia; Verheecke-Vaessen, Carol; Strub, Caroline; Fontana, Angélique; Guehi, Tagro; Schorr-Galindo, Sabine; Medina, Angel
Aspergillus carbonarius is the main producer of Ochratoxin A (OTA) in coffee. In the last few years, there has been an increasing interest in using yeast isolates as Biocontrol Agents to prevent OTA production in coffee cherries during the primary postharvest processing. Little is known about how climate change abiotic conditions of increased temperature (+2–4 °C), elevated CO2 (existing levels of 400 vs. 1000 ppm), and increased drought stress will impact biocontrol resilience. This study examined the effect of a three-way interaction between temperature (27, 30, and 33 °C) x water activity (aw) (0.90 and 0.95 aw) x CO2 level (400 vs. 1000 ppm) on the growth and OTA production of A. carbonarius and the resilience of three yeast strains’ biocontrol capacity on fresh coffee cherries. High aw (0.95), CO2, and temperature levels increased the production of OTA by A. carbonarius. All the yeast biocontrol strains significantly reduced A. carbonarius growth by at least 20% and OTA production by up to 85%. From the three strains used, the Meyerozyma caribbica strain (Y4) showed the best resilience to climate change, since it reduced both growth (50%) and OTA production (70%) under future scenarios of CO2 and aw at all temperatures tested, and should be the one selected for pilot scale experiments in Ivory Coast.