Land Application Research Articles

The binding effects and mechanisms of dissolved organic matter (DOM) on the fate of mercury in sludge anaerobic digestion combined with thermal hydrolysis

Dissolved organic matter (DOM) plays an important role in regulating the fate of mercury (Hg), e.g., mobility, bioavailability, and toxicity. Clarifying the role of DOM in binding Hg in the treatment processes of sewage sludge is important for relieving Hg contamination risks in land applications. However, the impacts of DOM on Hg binding in sewage sludge are still unclear. In this study, we investigated the evolution of Hg and its speciation in full-scale sludge anaerobic digestion (AD) with thermal hydrolysis. The role of DOM in binding Hg(II) was further analyzed. The results showed that AD with thermal hydrolysis led to an increase in the Hg content in the sludge (from 3.72 ± 0.47 mg/kg to 10.75 ± 0.16 mg/kg) but a decrease in Hg mobility (the mercury sulfide fraction increased from 60.56 % to 79.78 %). Further adsorption experiments revealed that at equivalent DOM concentrations, DOM with a low molecular weight (MW<1 kDa) in activated sludge, DOM with a medium molecular weight (1 kDa<MW<5 kDa) in thermally hydrolyzed sludge, and DOM with a high molecular weight (MW> 5 kDa) in both anaerobically digested sludge and conditioned sludge showed high binding amounts of Hg(II), with 1372.54, 535.28, 942.09 and 801.51 mg Hg/g DOM, respectively. Parallel factor analysis (PARAFAC) and fluorescence quotient (FQ) results showed that tryptophan-like and tyrosine-like substances had high binding affinities for Hg(II). Furthermore, X-ray photoelectron spectroscopy (XPS) indicated that the reduced organic sulfur contained in the DOM was potentially bound to Hg through the interactions of Hg-S and Hg-O. These results indicated that DOM may play special roles in regulating Hg speciation. The association between DOM and Hg(II), such as the significant positive correlation (p < 0.05) between the dissolution rate of Hg(II) and release of tryptophan-like substances during thermal hydrolysis, suggested the potential way for removing Hg from sludge.

Proposed improvements to Istibdal implementation management in the state of Penang

Purpose This study aims to examine the factors of implementing istibdal waqf and generating cash waqf funds through istibdal in Penang. This study was based on the previous problem statements, stating that waqf property could not be developed due to lack of cash funds. This has allowed the study to explore the factors for implementing istibdal waqf property and the extent to which the istibdal method can generate cash waqf funds in Penang. Design/methodology/approach This study adopted a qualitative method by conducting semi-structured interviews to achieve its research goals. Semi-structured interviews were conducted to comprehensively understand the current practice on istibdal cases in Penang State Islamic Religious Council (MAINPP) through official institutions concerned with waqf management practices in Penang. This research relied on purposive sampling to select the informants. It is a sampling strategy to select the informants in advance based on the research question. To achieve the purpose of this study, two officers from MAINPP were selected based on their working experience and specialisation criteria. As a result, several themes were successfully defined from the interview data before being analysed based on the content analysis method. Findings The results present three istibdal implementation processes outlined by MAINPP, namely, the istibdal implementation process for waqf land involved in the acquisition by state authorities (PBN), non-productive waqf land and istibdal applications from certain parties. The results also reveal two factors in implementing istibdal in Penang: the acquisition of waqf land by PBN and the application of istibdal for cemeteries by the Islamic Centre of Universiti Sains Malaysia. From the point of cash fund generation, no case of istibdal implementation records the generation of cash funds to MAINPP. Thus, this study ends with proposals for improving the process and implementing istibdal in Penang to generate cash funds to help MAINPP manage waqf properties. Research limitations/implications The study only focused on implementing factors and generating cash waqf funds through istibdal in Penang. At the same time, it can be expanded to other states like Terengganu, Johor and Kelantan. This study only interviewed officers who manage matters related to the affairs of waqf properties. Therefore, it is believed that the study can be extended to other respondents, such as experts in cash fund generation investments and others. Practical implications This study proposed improvements to the policy and practice of istibdal waqf property to MAINPP after the shortcomings were identified throughout this study. If improved, these proposals will significantly impact the waqf properties involved in implementing istibdal, where it can generate cash and ensure the constant economic value of waqf properties. Social implications This study has great implications for society through the development of a cash waqf fund that can provide great benefits to the needy, in addition to increasing funds for the welfare expenditure of Muslims through rental income, investment and development. Progress and significant impact on waqf property can provide a high indicator of the efficiency of an organisation in managing waqf property. This can attract the interest of the public, especially the wealthy, to always fulfil welfare through the waqf mechanism and share the wealth with the needy. Originality/value This study contributes to comprehensive field data on the implementation of istibdal in Penang. The data analysis results are significant to be used by the waqf property management.

Evaluating hydrothermal liquefaction hydrochar from sewage sludge as a phosphorus resource through struvite production

Hydrothermal liquefaction (HTL) has attracted considerable attention for valorizing sewage sludge to biofuels while the solid residue, hydrochar, has received little attention for its final application. In the current work hydrochar recovered from hot separation in a pilot-scale HTL plant is evaluated for its nutrient value, in particular as a sustainable Phosphorus (P) resource. Following thorough characterization of the hydrochar, P recovery as struvite (NH4MgPO4·6H2O) is investigated to produce a fertilizer with a lower heavy metal content that could be used in current agricultural practices. P extraction using inorganic (hydrochloric and sulphuric) and organic (citric) acids is evaluated by applying 0.1–1 mol/L of acids for 1–12 h with a liquid/solid ratio of 10 mL/g. A second-order polynomial model was established by response surface methodology (RSM) to predict the P extraction with different acids. The optimum operating conditions for maximum P extraction (94 %) are suggested as 0.7 M of acid strength (H2SO4) and 6.5 h of extraction time. Addition of citric acid (CA) during the struvite precipitation from acid-leached P solution was found to improve the struvite purity from 36.6 % to 54 % with a reduction in heavy metal content. Furthermore, morphological analysis validated the formation of struvite. Upon comparison with the regulations, hydrochar was found to exceed some of the heavy metal limits but was low in polyaromatic hydrocarbons (PAHs), per- and polyfluorinated substances (PFAS) and showed low toxicity to Aliivibrio fischeri. P extraction and struvite precipitation are shown to reduce heavy metal contents below regulatory limits with P recoveries from 40 % to 67 %. Thus, as an alternative to direct land application of hydrochar, harvested struvite from hydrochar could be applied as a fertilizer with no apparent environmental risk.

Leaching of antibiotic resistance genes and microbial assemblages following poultry litter applications in karst and non-karst landscapes

Antibiotic resistance is increasingly recognized as a critical challenge affecting human, animal, and environmental health. Yet, environmental dynamics and transport of antibiotic resistance genes (ARGs) and microbial communities in karst and non-karst leachate following poultry litter land applications are not well understood. This study investigates impacts of broiler poultry litter application on the proliferation of ARGs (tetW, qnrS, ermB, sulI, and blaCTX-M-32), class 1 integron (intI1 i), and alterations in microbial communities (16S rRNA) within karst derived soils, which are crucial and under-researched systems in the global hydrological cycle, and non-karst landscapes. Using large, intact soil columns (45 cm diam. × 100 cm depth) from karst and non-karst landscapes, the role of preferential flow and ARG transport in leachate was enumerated following surface application of poultry litter and simulated rain events. This research demonstrated that in poultry litter amended karst soils, ARG (i.e., ermB and tetW) abundance in leachate increased 1.5 times compared to non-karst systems (p < 0.05), highlighting the influence of geological factors on ARG proliferation. Notably, microbial communities in karst soil leachate exhibited increased diversity and abundance, suggesting a potential linkage between microbial composition and ARG presence. Further, our correlation and network analyses identified relationships between leachate ARGs, microbial taxa, and physicochemical properties, underscoring the complex interplay in these environmentally sensitive areas. These findings illuminate the critical role of karst systems in shaping ARG abundance and pollutant dispersal and microbial community dynamics, thus emphasizing the need for landscape-specific approaches in managing ARG dissemination to the environment. This study provides a deeper understanding of hydrogeological ARG dynamics but also lays the groundwork for future research and strategies to mitigate ARG dissemination through targeted manure applications across agricultural landscapes.

A comprehensive assessment of the economic and technical viability of a zero liquid discharge (ZLD) hybrid desalination system for water and salt recovery

Brine, a by-product of desalination and industrial facilities, is becoming more and more of an environmental issue. This comprehensive techno-economic assessment (TEA), focusing on the technical and economic aspects, investigates the performance and viability of a novel hybrid desalination brine treatment system known as zero liquid discharge (ZLD). Notably, this research represents the first instance of evaluating the feasibility and effectiveness of integrating three distinct desalination processes, namely brine concentrator (BC), high-pressure reverse osmosis (HPRO), and membrane-promoted crystallization (MPC), within a ZLD framework. The findings of this study demonstrate an exceptional water recovery rate of 97.04%, while the energy requirements stand at a reasonable level of 17.53 kWh/m3. Financially, the ZLD system proves to be at least 3.28 times more cost-effective than conventional evaporation ponds and offers comparable cost efficiency to alternatives such as land application and deep-well injection. Moreover, the ZLD system exhibits profitability potential by marketing both drinking water and solid salt or solely desalinated water. The daily profit from the sale of generated water varies from US$194.08 to US$281.41, with Greece and Cyprus attaining the lowest and highest profit, respectively. When considering the sale of both salt and water, the profit rises by 8% across all locations.

Impacts of vegetable processing and cheese making effluent on soil microbial functional diversity, community structure, and denitrification potential of land treatment systems.

The cheese making and vegetable processing industries generate immense volumes of high-nitrogen wastewater that is often treated at rural facilities using land applications. Laboratory incubation results showed denitrification decreased with temperature in industry facility soils but remained high in soils from agricultural sites (75% at 2.1°C). 16S rRNA, phospholipid fatty acid (PLFA), and soil respiration analyses were conducted to investigate potential soil microbiome impacts. Biotic and abiotic system factor correlations showed no clear patterns explaining the divergent denitrification rates. In all three soil types at the phylum level, Actinobacteria, Proteobacteria, and Acidobacteria dominated, whereas at the class level, Nitrososphaeria and Alphaproteobacteria dominated, similar to denitrifying systems such as wetlands, wastewater resource recovery facilities, and wastewater-irrigated agricultural systems. Results show that potential denitrification drivers vary but lay the foundation to develop a better understanding of the key factors regulating denitrification in land application systems and protect local groundwater supplies. PRACTITIONER POINTS: Incubation study denitrification rates decreased as temperatures decreased, potentially leading to groundwater contamination issues during colder months. The three most dominant phyla for all systems are Actinobacteria, Proteobacteria, and Acidobacteria. The dominant class for all systems is Nitrosphaeria (phyla Crenarchaeota). No correlation patterns between denitrification rates and system biotic and abiotic factors were observed that explained system efficiency differences.

Basics of Catalyst for Internal Combustion Engine Applications - Future Prospect of After-treatment Catalyst System for Ships Based on Past Land Application Technologies

Basics of Catalyst for Internal Combustion Engine Applications - Future Prospect of After-treatment Catalyst System for Ships Based on Past Land Application Technologies

Biochar pH reduction using elemental sulfur and biological activation using compost or vermicompost

This study aimed to improve biochar’s quality for arid land applications by using elemental sulfur as a pH reducer agent co-applied with compost or vermicompost as biological activators. Biochar pH was decreased by the addition of elemental sulfur, with the highest reduction from 8.1 to 7.2 occurring when co-amended with vermicompost. Elemental sulfur increased the water-soluble concentrations of calcium, magnesium, and many other elements, and stimulated substrate-induced respiration, especially when co-amended with vermicompost. The bacterial diversity community structure were significantly affected by all treatments. The Shannon index significantly increased in response to compost and sulfur treatments, while the vermicompost treatments showed higher microbial evenness and equitability diversity indices. Multivariate analyses indicated that elemental sulfur oxidation was associated with specific sulfur-oxidizing bacterial clusters. Integrating biochar with sulfur and (vermi)compost was found to be a promising sustainable technology for managing excessive biochar alkalinity, increasing its fertility and potential for application in aridlands.

Towards evaluating the conditional probability of waterborne microbial risks associated with critical rainfall events following land application of animal waste — A focus on Irish pastures

ABSTRACT Modelling surface runoff and infiltration in an agricultural watershed is essential for understanding the nutrient cycle and water quality management. This research evaluates the critical rainfall events causing maximum surface runoff and infiltration. Empirical models such as Soil Conservation Service (SCS) curve number and Explicit Green-Ampt (EGA) were analysed for different soil hydraulic conditions and storm events with specific return periods. The present study forecasted the maximum daily rainfall and intensity as 113.6 mm and 19.9 cm h–1, respectively, considering a 100-year return period storm. The deterministic part of the model calculates the daily maximum surface runoff as 5.51 cm (from the SCS model). The EGA model revealed that the rainfall intensity of 0.143, 0.163, 0.175, 0.179, 0.181, 0.182, and 0.182 cm h−1 (duration of 24 h) was found critical for 1, 2, 5, 10, 25, 50, 100 year return period of the storm, respectively in different soil texture classes (sand, loamy sand, sandy loam, loam, silt loam, sandy clay loam, clay loam, silty clay soils). Exceptions imply for three occasions where the intensity of 0.407 cm h−1 and duration of 18 h produced maximum infiltration for silty clay loam, and intensity of 0.352 and 0.354 cm h−1 with 9 h rainfall (each) produced maximum infiltration for clay. The probabilistic model revealed that a daily storm event probability of 2.74 × 10–5 is associated with a simulated mean runoff depth of 0.69 cm and infiltration of 20.7 cm. Critical rainfall probabilities calculated in this study can be multiplied with the overall microbial/pollutant human health risk assessment framework to calculate conditional probability and better estimate microbial risk through the drinking water pathway. This study is very relevant for the wet climatic condition of Ireland, where most land use is pastures.

Application of untreated versus pyrolysed sewage sludge in agriculture: A life cycle assessment

Recycling of phosphorus (P) from waste streams such as sewage sludge to agriculture is essential in order to ensure future food security. Land application of sewage sludge is controversial due to its content of pollutants, such as heavy metals and toxic organic compounds. Pyrolysis is a technology that can eliminate harmful contaminants while enabling the recycling of P in the sludge. Organic pollutants are degraded during pyrolysis, while most of the P remains and approximately 40 % of the carbon is retained in a stable form in the biochar. When performing pyrolysis at a temperature of around 800 °C or more, cadmium is evaporated and can be separated from the biochar. Electricity-driven pyrolysis facilitates this by means of easier temperature control. The aim of the present study was to undertake a Life Cycle Assessment (LCA) to evaluate the environmental impacts of high-temperature electricity-driven pyrolysis of sewage sludge, including the separation of cadmium, and field application of sludge biochar as compared with sewage sludge storage and field application. The results showed that pyrolysis can offer a more climate-friendly solution due to avoided greenhouse gas emissions from the sludge and to carbon sequestration of the biochar. However, field application of untreated sludge resulted in a higher application of nitrogen (N) and more plant-available P. Agricultural modelling tools indicated that this produces higher crop yields than biochar application. In the LCA model, higher crop yields lead to savings in land use and water consumption as the higher yields can replace other crop production. The lower plant availability of biochar P implies a possible risk of lower yields when the P application is restricted based on total P, and a risk of greater P loss with soil erosion to the environment. Overall, the present study stresses the importance of including the long-term agronomic impacts of sludge and biochar field application in LCAs, and highlights the trade-offs that need to be considered in decision-making regarding the implementation of pyrolysis technology.

Research on SAR image denoising method based on feature extraction

AbstractDue to the excellent characteristics of Synthetic Aperture Radar (SAR), it has become an important technical means for land and sea target detection applications worldwide. However, the SAR image imaging process is often accompanied by speckle noise, which affects the accuracy of target detection. For this problem, this paper proposes an SAR image reconstruction model based on image denoising and feature extraction. Given a noisy SAR image, at each pixel of the image, the value of the singularity index of a metric defined by the signal gradient norm density is calculated. Then through a hierarchical decomposition of these singular indices, a set of pixels containing the most informative feature set of the image is extracted, and a denoised image is reconstructed using the extracted features. In comparison to traditional filtering and denoising techniques such as non‐local filtering, this algorithm achieves remarkable local filtering and denoising effects while preserving the image's texture information. The denoising performance of the proposed method is evaluated through a series of quantitative indicators and visual comparisons. The results demonstrate that this method effectively reduces background clutter, resulting in a higher contrast between the target and the background.

Investigating the sources and fate of per- and polyfluoroalkyl substances (PFAS) in food waste compost

Composting municipal food waste is a key strategy for beneficially reusing methane-producing waste that would otherwise occupy landfill space. However, land-applied compost can cycle per- and polyfluoroalkyl substances (PFAS) back into the food supply and the environment. We partnered with a pilot-scale windrow composting facility to investigate the sources and fate of 40 PFAS in food waste compost. A comparison of feedstock materials yielded concentrations of ∑PFAS under 1 ng g−1 in mulch and food waste and at 1380 ng g−1 in leachate from used compostable food contact materials. Concentrations of targeted ∑PFAS increased with compost maturity along the windrow (1.85–23.1 ng g−1) and in mature stockpiles of increasing curing age (12.6–84.3 ng g−1). Among 15 PFAS quantified in compost, short-chain perfluorocarboxylic acids (PFCAs) – C5 and C6 PFCAs in particular – led the increasing trend, suggesting biotransformation of precursor PFAS into these terminal PFAS through aerobic decomposition. Several precursor PFAS were also measured, including fluorotelomer carboxylic acids (FTCAs) and polyfluorinated phosphate diesters (PAPs). However, since most targeted analytical methods and proposed regulations prioritize terminal PFAS, testing fully matured compost would provide the most relevant snapshot of PFAS that could be land applied. In addition, removing co-disposed food contact materials from the FW feedstock onsite yielded only a 37 % reduction of PFAS loads in subsequent compost, likely due to PFAS leaching during co-disposal. Source-separation of food contact materials is currently the best management practice for meaningful reduction of PFAS in food waste composts intended for land application.

Comparison of properties of brown coal and bio-mass-based substitute fuels

Due to the EU climate change strategy, there are many coal-fired heating plants looking for new fuel. One of the possibilities is biomass-based fuels. This term is quite general because the final technology can be different because of properties of different types of biomasses. The sustainable solution can be the use of biomass residues. This article is about long-term monitoring of the properties of brown coal, agglomerated herbaceous biomass from agricultural residues, and wood chips from harvesting residues. 702 samples of brown coal, 715 samples of plant pellets and 607 samples of wood chips were analyzed, which were supplied do commercial heating plant between the years 2021-2023. The water and ash content, lower heating value (LHV) and higher heating value (HHV), were analyzed. The mineral composition of the fuels was determined quarterly from mixed samples. In the case of water content, the lowest values were achieved for herbaceous pellets (11.35%), due to their previous drying. The moisture content of the wood chips fluctuated. The average was 36.34%, with a maximum deviation of up to 49.9%. The average water content in brown coal was around 28.63%. In detail, there is a seasonal influence of the weather. In the case of ash content determination, the values for brown coal and herbaceous pellets are similar (slightly above 5%), wood chips contain less ash (2.2%). The results for the wood chip samples fluctuated again. There were samples consisting of chipped logs (0.33% ash) and samples with a large proportion of forest soil (4.37%). The highest average HHV values were achieved for brown coal (18.98 MJ/kg), followed by herbaceous pellets (15.84 MJ/kg) and wood chips (11.02 MJ/kg). These differences may cause a decrease in steam output due to a limitation of space in the combustion chamber of the boiler after the retrofit. In the case of the content of nonmetallic elements, a different character of the biomass is evident, consisting of a higher oxygen content (38% vs 19%) and a lower carbon content (48% vs 68%). Biomass also contains less sulfur, but the high chlorine content of 0.12% compared to 0.02% in wood chips was determined in herbaceous pellet samples. For a heating plant, this means intensive chlorine corrosion or exceeding the emission limits of HCl. The solution can be in DSI technology. Brown coal contains more Ti, V, Li, Sr, Be, Na, Fe, and Al. The biomass contains more biogenic elements, especially Ca, K, P, and Zn, which allows the ash to be used for land application. For the combustion process, a significantly higher content of alkali has an adverse effect, causing a decrease of the melting temperature of ash, which can lead to technological problems, such as the formation of a material based on alkaline glass, which decreases heat transfer and combustion efficiency. Most often, this complication is solved by micro detonations and more frequent maintenance. The contents of Hg, Cd, and Tl in the samples were below the detection limit.

APPLICATION OF USING SLAUGHTERHOUSE WASTE FOR BOOSTING THE GROWTH OF SPINACH

Slaughterhouse waste is capable of causing serious bacterial, viral and pathogenic diseases both in humans and animals. Slaughterhouse wastewater contains fat, proteins, suspended solids and diluted blood. Due to this, organic as well as nutrient profusion in wastewater is very high. These partially solubilized residues pose a real threat to human health if left out in riverbeds and other water bodies untreated. Processing of blood requires a high capital investment on heavy instruments for slaughtering and collection of blood. The hazard could be minimized by environmentally friendly and cost-effective disposal methods. This waste could be used for land application via composting, as it is a rich source of primary plant nutrients i.e. N, P and K as well as growth promoting microbes and organic substances. Keeping in view the above-mentioned facts, a pot trial was conducted in the wire house of the Institute of Soil and Environmental Sciences. We mixed the soil with slaughterhouse waste before sowing. Three seedlings of spinach were maintained after germination. Water was applied as needed by the plants. Recommended doses of N, P, and K fertilizers were applied. Data regarding physiological parameters, growth and yield was collected and analyzed at appropriate growth stages. After harvesting, plant tissues (root and leave) and soil samples was subjected to analysis for plant nutrients provision. Analysis of data was done following standard statistical procedure. Slaughterhouse waste improves the plant growth. Results showed that blood, intestine and dry matter significantly affect the plant growth parameter of spinach in natural soil. Plant height was increased up to 92 %, root length 194 %, shoot dry weight 60 % and root dry weight 169 % with blood at (120 ml), intestine (100 g) and dry matter (20 g) as compared to control. All the treatments significantly improved these parameters but blood, intestine and dry matter increased chlorophyll contents 84%, relative water contents 21 %, photosynthetic rate 91%, transpiration rate 95%, and stomatal conductance 58 %, and decreased electrolyte leakage up to 54% in spinach.

Biosolids management and utilizations: A review

Biosolids, derived from wastewater treatment processes, have garnered increasing attention as a valuable resource due to their rich organic and inorganic constituents, which can be beneficially utilized in multiple sectors, including agriculture, civil engineering, and energy recovery. The present review article begins by providing an overview of biosolids, including their production methods and classification based on treatment processes. Subsequently, the chemical composition of biosolids is explored, highlighting the diverse array of organic and inorganic components present. The characterization techniques employed for analyzing biosolids, such as spectroscopy, chromatography, and microscopy, are thoroughly discussed, emphasizing their role in determining the quality and suitability of biosolids for different applications. Furthermore, the environmental impacts associated with biosolids disposal are extensively examined. This includes the potential risks posed by heavy metals, pathogens, and emerging contaminants, as well as strategies for mitigating these risks through proper treatment and management practices. In addition to environmental considerations, the article explores the various products that can be derived from biosolids. These include organic matter-rich soil amendments for agricultural applications, inorganic nutrient supplements for enhancing plant growth, and the potential for energy recovery through anaerobic digestion and thermal conversion technologies. The utilization of biosolids in civil engineering projects, such as landfill capping and construction materials, is promising. Land application of biosolids also can have economic and waste management benefits (e.g., conservation of landfill space; reduced demand on non-renewable resources like phosphorus; and a reduced demand for synthetic fertilizers).

Double pulsed current adopted in local dry underwater WAAM to simultaneously enhanced strength and ductility of 308 L multi-layer component

The double pulsed current waveform modulation was applied to address the severe challenges of greatly declined strength and ductility caused by continuous heat accumulation and water cooling in local dry underwater wire arc additive manufacturing (LDU-WAAM) process. The microstructures and mechanical performance of 308 L stainless steel multi-layer components prepared by LDU-WAAM using single pulsed waveform (SPW) and double pulsed waveform (DPW) were comprehensively investigated in this work. The results demonstrate that the microstructures of LDU-WAAM parts were both composed of abundant columnar crystals and few equiaxed crystals. Extremely directional columnar crystals dominated in each deposited layer centre prepared by SPW, while the weakened growth tendency of columnar crystal and uniform microstructure were achieved by DPW. DPW exhibited outstanding stirring action in LDU-WAAM process, which was conducive to the refined grain, improved liquidity of deposited metal, increased ferrite content, dislocation density, and austenite deformed twinning content compared with the SPW multi-layer component. Hence, the average microhardness, ultimate tensile strength, and elongation of DPW deposited layers were improved to 204.7 HV, 659.2 MPa, and 24.9 %, respectively, which enhanced by 10.1 %, 12.5 %, and 37.5 % than that of SPW sample. The research results provide a new technique optimization method to simultaneous enhance the strength and ductility of LDU-WAAM process and promote the landing application of LDU-WAAM in underwater on-site repair.

Life cycle and techno-economic assessment of bioresource production from wastewater

Thermochemical conversion technologies present an opportunity to flip the paradigm of wastewater biosolids management operations from energy-intense and expensive waste management processes into energy-positive and economical resource extraction centers. Herein, we present a uniform “grading framework” to consistently evaluate the environmental and commercial benefits of established and emerging wastewater biosolids management processes from a life cycle and techno-economic perspective. Application of this approach reveals that established wastewater biosolids management practices such as landfilling, land application, incineration, and anaerobic digestion, while commercially viable, offer little environmental benefit. On the other hand, emerging thermochemical bioresource recovery technologies such as hydrothermal liquefaction, gasification, pyrolysis, and torrefaction show potential to provide substantial economic and environmental benefit through the recovery of carbon and nutrients from wastewater biosolids in the form of biofuels, fertilizers, and other high-value products. Some emerging thermochemical technologies have developed beyond pilot scale although their commercial viability remains to be seen.

Value of food waste-derived fertilisers on soil chemistry, microbial function and crop productivity

Food waste management through composting and anaerobic digestion are sustainable waste management processes that can promote sustainable agricultural practices by recycling nutrients, reducing reliance on synthetic fertilisers, and conditioning soils. However, compost and digestate (anaerobic digestate effluent) are low nutrient value fertilisers, limiting their use within agriculture due to the large volumes required for land application. Alternatively, food waste-derived fertilisers could be used alongside chemical fertilisers to improve crop growth further and reduce demand on synthetic fertilisers. Therefore, this study evaluated the impact of food waste-derived fertilisers (compost, liquid digestate (LD), and solid digestate (SD)) on plant growth (Ryegrass) when applied at a rate of 50 kg N·ha−1 in combination with synthetic fertiliser (Urea Ammonium Nitrate (UAN)) at a rate of 0 or 50 kg N·ha−1. Ryegrass growth, soil chemistry, and rhizosphere microbial communities were investigated. SD in combination with UAN yielded the largest shoot biomass, while sole UAN at any application rate was not significantly different from the control. Beneficial plant growth phyla were in higher abundance in all treatments amended with food waste-derived fertilisers, and putative genes encoded for N fixing were found in higher abundances in all soil amendments compared to control. This highlights the value of food waste-derived fertilisers within agriculture. However, while drying would logically reduce costs associated with digestate transport, ammonia volatilisation led to significant N losses, reducing the fertiliser value of SD. Future studies should explore methods to mitigate ammonia valorisation to enhance the final fertiliser value of SD.

Improvement of labyrinth seal performance using the partial honeycomb lands

In this study, a partial honeycomb land was proposed for improving the sealing performance of a labyrinth seal which has been widely applied to the low-pressure section of a gas turbine. The partial honeycomb land in this experiment is distinguished by a solid strip under the fin of the honeycomb land labyrinth seal. The tested fin front angle of the labyrinth seal was 60°, and the clearance size ranged from 1.15 to 2.82 times the fin tip thickness. The honeycomb cell diameter was 4 times the fin tip thickness, and the honeycomb cell depth was 10.58 times the fin tip thickness. The experiments were conducted under pressure ratios ranging from 1.1 to 2.5, and it was confirmed that the application of the partial honeycomb land resulted in a maximum 39.4 % reduction in the discharge coefficient. Computational Fluid Dynamics (CFD) analysis revealed that the application of the partial honeycomb land altered the flow of leakage, leading to a decrease in the effective clearance. It was confirmed that, for the honeycomb labyrinth seal with smaller clearance, the sealing performance degradation for the conventional honeycomb land case due to the weakened vortex inside the fin cavity was not observed for the case with partial honeycomb land. Therefore, the improvement in sealing performance of the labyrinth seal with partial honeycomb land was attributed not only to the reduction in the effective leakage flow area, but also to the maintained vortex size, which induced resistance to the leakage flow even in smaller clearance conditions.

Impact of cycling conditions on lithium-ion battery performance for electric vertical takeoff and landing applications

The development of better electrochemical energy storage systems has sparked significant interest in using Li-ion batteries for electric vertical takeoff and landing (eVTOL) applications. To ensure the optimal performance and safety of onboard batteries, their behavior under different charging/discharging protocols and environmental conditions must be understood. This paper presents a comprehensive evaluation of commercial Li-ion batteries for eVTOL applications, focusing on their responses to varying charging/discharging strategies and mechanical vibrations experienced during flight. Through controlled experiments, the effects of rapid cycling on battery performance were investigated, including effects on lifespan, capacity, and internal resistance. Additionally, the impact of mechanical vibrations on battery behavior was assessed to identify potential challenges for onboard batteries. The results of this study revealed intriguing insights into the interplay between temperature, vibration, and battery performance. This work contributes to the broader adoption of electric aerial transportation, promising a greener and safer future for urban mobility.