1,019 research outputs found

    Heavy metal contamination of faecal sludge for agricultural production in Phnom Penh, Cambodia

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    To achieve the universal target of ‘safely managed sanitation’ set out in UN Sustainable Development Goal 6, the world needs to increase its rate of progress, since e.g. Phnom Penh, the capital of Cambodia, currently has zero percent safely managed sanitation. One way to promote safer faecal sludge management is to shift to a more circular system with nutrient recycling, but this carries the risk of heavy metal accumulation in the environment. This study analysed the concentrations of heavy metals in raw faecal sludge from various sources and assessed the appropriateness of resource recovery and reuse in relation to the heavy metal and nutrient loads in faecal sludge. A total of 42 samples collected from sludge disposal sites in Phnom Penh during the dry and rainy seasons were analysed for heavy metals and physicochemical parameters. Mean measured concentrations of heavy metals in faecal sludge samples decreased in the order Zn > Cu > Pb > Cr > Ni > Hg > As > Cd in both seasons but were higher in the rainy season, probably due partly to inflow from stormwater drains and run-off from roads during storm events. All elements analysed were within the permissible limits for application to land according to EU standards and USEPA. However, Hg and Zn concentrations exceeded the tolerance limits for local organic fertiliser and Swedish limits for compost. Faecal sludge is thus not an appropriate fertiliser considering the risk of heavy metal accumulation in relation to phosphorus recovered. Options to avoid recirculating pollutants to the environment include upstream prevention of pollution, source separation of household wastewater fractions and use of biosolids as a soil conditioner together with other fertilisers or for soil production. Additional studies are needed on these options if sanitation stakeholders are to close the nutrient loop

    Composting of distillery spent wash

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    Distillery spent wash, a by-product of the alcoholic beverage industry, is an organic waste whose management poses significant challenges due to its acidity, high organic load, notable content of polyphenols, macronutrients, micronutrients and heavy metals. In Europe, billions of liters of distillery waste are generated annually and its eco-unfriendly disposal can cause severe environmental and health impacts. Composting is a viable management strategy to treat and manage distillery slop promoting the recycling and stabilization of organic matter and nutrients in the material. The review examines different composting methods, such as single composting, co-composting and vermicomposting, along with their benefits and drawbacks. To optimize composting effectiveness, various materials, such as sewage sludge, vinasse, green and animal manure, inorganic amendments, bagasse, filter cake and municipal solid waste, among other agro-food and animal bio-wastes, can be used as a source of nitrogen and microorganisms. Also, the usage of different materials and mixtures aims to enhance the composting process increasing the degradation rate and the quality of the compost. The challenges of distillery spent wash composting are also covered in the paper which are mainly due to its characteristics, including high salt content, low carbon-to-nitrogen ratio, low pH and potential phytotoxicity. The paper concludes that composting distillery spent wash is an effective and sustainable waste management solution for recovering valuable nutrient resources and producing a stable nutrient-rich organic soil amendment. The produced compost can improve crop yields, nutrient absorption by plants and plant biomass and contribute to soil properties and restoration. The review provides insights into the current state of distillery spent wash composting and recommends future research directions to improve efficiency and expand potential applications

    Valorización sostenible de lodos y residuos agroalimentarios para la producción de hidrógeno, metano y biofertilizante: transición a la economía circular

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    Los principales retos de la sociedad actual son la lucha contra la contaminación, el cambio climático y las emisiones de gases efecto invernadero asociadas, principalmente, a la creciente demanda energética mundial. La búsqueda de soluciones sostenibles ha supuesto un importante foco de investigación para la búsqueda de fuentes energéticas alternativas a los combustibles fósiles. Además, aún siguen sin resolverse los problemas ligados a la generación incontrolada de residuos orgánicos de diferentes procedencias. Así, por un lado, la creciente implementación de plantas de tratamiento de aguas residuales ha conllevado al aumento en la generación de lodos de depuradora difíciles y costosos de gestionar por dichas plantas. Por otro lado, en Andalucía y, concretamente, en la comarca de Jerez de la Frontera, el sector vitivinícola genera grandes cantidades de desechos procedentes de la producción del vino. Asimismo, otro sector generador de residuos en auge lo componen las granjas y explotaciones avícolas debido a la creciente demanda de exportación cárnica. Estas instalaciones generan grandes cantidades de estiércol avícola que requieren una adecuada gestión previa a su aplicación al suelo. La presente Tesis Doctoral propone un tratamiento conjunto de lodos de depuradora y residuos agroalimentarios (vinazas de vino y estiércol avícola). El proceso seleccionado para este fin ha sido la digestión anaerobia aplicada mediante diferentes tecnologías: procesos monoetapa y sistemas con separación simultánea de fases de temperatura y de microorganismos. Esta última tecnología requiere dos digestores conectados en serie: en el primer digestor se fomenta la hidrólisis/acidogénesis del sustrato para generar biohidrógeno, mientras que en segundo se opera en condiciones metanogénicas para la obtención de biometano y biofertilizante. Adicionalmente, se analizan diferentes temperaturas de operación, termofílica y mesofílica, de forma que se optimice tanto la generación de H2 y CH4 en el biogás como la producción de un digestato de características adecuadas para su uso como biofertilizante. El estudio y optimización de estas tecnologías anaerobias permitirá la gestión simultanea de tres desechos generados en el entorno cercano a la comarca del Jerez, solucionando el problema ambiental derivado de la generación de los mismos y generando, fruto del proceso, productos de gran valor añadido tales como biohidrógeno, biometano y biofertilizante. Con ello se consigue cerrar el ciclo productivo y enfocar el problema desde el prisma de la economía circular. La presente Tesis Doctoral se presenta como compendio de nueve publicaciones científicas en las cuales se recogen los resultados obtenidos en cada etapa experimental desarrollada. Se comienza con un análisis bibliométrico del estado del arte de la digestión anaerobia (recogido en la revista International Journal of Hydrogen Energy), seguido de la exposición y análisis de los resultados más relevantes obtenidos en el desarrollo de cada etapa de experimentación a escala de laboratorio (7 publicaciones científicas en revistas de alto impacto en el sector). Adicionalmente, se incluye una publicación en la que se analiza la viabilidad tecno-económica de la tecnología anaerobia para la co-digestión anaerobia de lodos y residuos agroalimentarios en tres diferentes escenarios. Los primeros ensayos experimentales abordados tienen como objetivo determinar la proporción óptima de estiércol avícola que habría que añadir al lodo de depuradora y a la vinaza para generar biogás, así como los rangos de temperatura de operación más apropiados en cuanto a producción de biohidrógeno y biometano. Las mezclas de sustratos analizadas consisten en proporciones de lodo y vinaza (50:50) y diferentes proporciones de estiércol avícola. Las mezclas en las proporciones seleccionadas, se someten a test normalizados de potencial de biodegradación para la obtención de biohidrógeno o biometano, según el caso, a diferentes temperaturas operativas. Concretamente, se estudia el potencial bioquímico de hidrógeno (BHP) de las mezclas en tres rangos de temperatura diferentes (mesófilico (35ºC), termofílico (55ºC) e hipertermofílico (70ºC). Adicionalmente se desarrollan estudios paralelos para identificar el potencial bioquímico de metano (BMP) en rango mesofílico. Los resultados obtenidos muestran que la proporción de lodo:vinaza:estiércol avícola óptima es 49.5:49.5:1, con el máximo rendimiento de hidrógeno (27,10 mLH2/gSV) en rango de temperatura termofílico. Para los otros rangos de temperatura estudiados, la producción de hidrógeno es prácticamente nula. Con los efluentes procedentes de los ensayos de fermentación ácida de la etapa anterior se configuran nuevos test para identificar el potencial bioquímico de metano de cada efluente ácido operando en rango mesofílico. Los resultados experimentales indican que el máximo rendimiento de metano se alcanza con el efluente procedente de los test BHP operando en rango hipertermofílico, llegando a alcanzar valores 117,00 y 113,00 mLCH4/gSV para las mezclas lodo:vinaza (50:50) y lodo:vinaza:estiércol avícola (49,5:49,5:1), respectivamente. En cambio, los tests BMP desarrollados con el efluente ácido de los tests BHP en rango termofílico presentan menores valores, con un máximo de 52,05 mLCH4/gSV para la mezcla con estiércol avícola en proporción 49,5:49,5:1 lodo:vinaza:estiércol avícola. El análisis cinético de los resultados experimentales pone de manifiesto que la producción de hidrógeno se ajusta al modelo de Cone mientras que los datos experimentales de producción de metano se ajustan al modelo de Gompertz modificado. Estos ensayos permitieron el desarrollo de tres artículos científicos, de los cuales dos se encuentran publicados en la revista científica Journal of Hydrogen Energy y otro bajo revisión en la revista Journal of Cleaner Production. Posteriormente, y en base a estos resultados, se diseñan nuevos experimentos en régimen de alimentación semicontinuo a escala de laboratorio utilizando reactores de tres litros. Estos ensayos permiten optimizar el funcionamiento del proceso de co-digestión de lodo y vinaza así como de la tri-digestión lodos+vinaza+estiércol avícola en rango mesofílico para diferentes tiempos hidráulicos de retención (THR). Asimismo, se llevan a cabo estudios paralelos para optimizar los procesos de digestión en fases separadas termofílico-acidogénico y mesofílico-metanogénico del proceso de tri-digestión de lodo, vinaza y estiércol avícola. Los rangos de temperatura seleccionados son consecuencia de los resultados previos, en los que la mayor producción de hidrógeno se registraba para temperaturas termofílicas. El estudio y análisis comparativo de los principales resultados del estudio abordado para los procesos monoetapa ha sido publicado en la revista internacional Fuel. Los resultados indican que la tecnología de tri-digestión anaerobia en rango mesofílico, operando con una mezcla de sustratos de lodo, vinaza y estiércol avícola en proporción 49.5:49.5:1 es la que obtiene la mayor eficiencia depurativa en base a demanda química de oxígeno total (DQOT) (51%), sólidos volátiles (SV) (57%) y rendimiento de metano (262,00 mLCH4/gSV). Además, un análisis de patógenos pone de manifiesto la ausencia de patógenos en el efluente digerido, por lo que las condiciones de operación ensayadas consiguen la higienización del efluente haciéndolo apto para su catalogación como biosólido clase A según la Agencia de Protección Ambiental de EEUU (US EPA). Las dos siguientes publicaciones recogen los resultados obtenidos en las etapas de optimización de las fases termofílica-acidogénica y mesofílica-metanogénica de forma individual. Para ello, se abordan ensayos a diferentes THR (10, 8, 6, 5, 4 y 3 días) hasta observar desestabilización de los sistemas, correspondientes a tasas de carga orgánica (OLR) aplicadas de 2,93; 3,48; 4,62; 6,18; 6,82 y 7,75 gSV/L/d. Para cada THR se evalúan los rendimientos de generación de biohidrógeno y biometano, las eficacias depurativas, actividad microbiana y concentración de patógenos. Los resultados obtenidos indican que el THR para una operación óptima de la fase acidogénica es de 5 días, mientras que para fase metanogénica es de 12 días. Así, la primera fase termofílica-acidogénica se alcanza un valor de rendimiento de hidrógeno máximo de 40,41 mLH2/gSV con una actividad microbiana 5,64e-11LH2/cells para el THR de 5 días. En la etapa mesofílica-metanogénica, la máxima eficiencia de depuración de SV (56%) y el máximo rendimiento de metano registrado (391,00 mLCH4/gSV) se obtiene a 12 días-THR con la mayor eliminación de patógenos en el efluente. Estas condiciones permiten obtener un efluente que cumple con las especificaciones para ser clasificado como biosólido clase A según la US EPA. Es interesante resaltar la correlación positiva que se establece entre el aumento de OLR aplicada al sistema y el aumento de la actividad microbiana en el mismo. Estos estudios han permitido la elaboración de dos artículos científicos de los cuales uno se encuentra bajo revisión en la revista científica Biomass and Bioenergy y el otro fue publicado en la revista Chemical Engineering Journal. Los siguientes estudios abordados en régimen semicontinuo de co-digestión de lodo, vinaza y estiércol avícola a escala de laboratorio van dirigidos a realizar un estudio comparativo del funcionamiento de las tecnologías seleccionadas: co-digestión anaerobia convencional en una sola etapa y dos diferentes rangos de temperatura (termofílica y mesofílica) y co-digestión anaerobia con separación de fases y de temperatura. Las condiciones que se analizan son las óptimas de operación para los procesos monoetapa (13 días-THR) y para el proceso con separación de fases (20 días-THR). Los resultados obtenidos mostraron que la separación de fases acidogénica-metanogénica y 20 días-THR presenta beneficios tales como una mayor eficiencia depurativa medida como DQOT (65%), siendo este valor un 26% y 17% superior a los datos obtenidos en condiciones el proceso monoetapa termofílico y mesofílico respectivamente. La eficacia de eliminación de SV alcanza el 90%, mientras que los reactores monoetapa arrojan valores de 41% y 43% de eliminación de SV, para las condiciones termofílica y mesofílica, respectivamente. Asimismo, se registra un mayor rendimiento de metano (320,00 mLCH4/gSV) al que hay que sumar la obtención de biohidrógeno en la primera fase del proceso. En conclusión, la tecnología con separación de fases de temperatura y microorganismos supone una mejora tecnológica a considerar por las estaciones depuradoras que pretendan mejorar su eficacia energética. Los resultados de este estudio fueron publicados en la revista científica Fuel. Finalmente, con el fin de comprobar la viabilidad de la implementación de esta tecnología, se lleva a cabo un estudio tecno-económico que abarca a las tres condiciones de co-digestión anaerobia estudiadas (co-digestión anaerobia mesofílica monoetapa, termofílica monoetapa, y co-digestión anaerobia con separación de fases de temperaturas y de microorganismos) aplicando herramientas de estudio de rentabilidad económica de cara a su implementación a escala industrial. El estudio confirma la viabilidad tecno-económica del proceso de separación de fases, mostrando los mejores datos de rentabilidad en su implementación a escala industrial frente a la co-digestión anaerobia en una sola etapa. Los resultados de este estudio se recogen en la novena publicación científica en la revista Internacional Journal of Environmental Management que forma parte de esta Memoria de Tesis Doctoral

    Sequential hydrothermal carbonization and CO2 gasification of sewage sludge for improved syngas production with mitigated emissions of NOx precursors

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    Due to high moisture and protein contents in sewage sludge (SS), conventional thermal treatment of SS is energy-intensive and a large amount of harmful nitrogen-containing gases are emitted. In this study, a sequential hydrothermal carbonization (HTC) and CO2 gasification system has been proposed to effectively improve the gasification efficiency and considerably reduce the emissions of NOx precursors (i.e., NH3 and HCN) in SS treatment. Yield and quality of syngas were comprehensively investigated during CO2 gasification in terms of various temperatures with different dosages of CaO additive in HTC, and varied reaction temperature and CO2 percentage in gasification process. On the whole, CO2 gasification of SS derived hydrochar (HC) demonstrated obvious reduction of tar formation from 10.9 to 6.8 % and enhancement of calorific value of formed syngas from 14.1 to 15.7 MJ/Nm3. Production of NOx precursors was greatly reduced due to formed non-active quaternary-N in HC, while HTC with CaO favored the mitigated NOx precursors in syngas owing to enriched pyrrole-N and quaternary-N therein. Catalytic tar decomposition and Boudouard reaction in CO2 gasification were responsible for the distinct reduction of tar formation, and notable increase of carbon conversion ratio and syngas yield. Although facilitated catalytic gasification in CO2 atmosphere can maximize syngas yield, lower portion of CO2 (ca. 20 %) was more beneficial to drastically mitigate emissions of NOx precursors, especially the reinforced transformation of NH3 to N2. The fundamental knowledge could ultimately help to achieve significant abatement of NOx precursors during CO2 gasification for improved syngas production.publishedVersionPeer reviewe

    A feasibility study on integrating electric buses with waste gasification for a green public transport system and solid waste management

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    Waste management and public transport are two major issues requiring decarbonisation in the face of climate change and environmental concerns related to global warming. Green transport systems are classified as zero or low carbon alternatives to the fossil fuel-based approach and vehicles. These systems rely on zero emission fuels such as hydrogen. Thermochemical processes (e.g., gasification) and biochemical technologies (e.g., fermentation) can convert carbon-based feedstock such as waste to produce desirable products like hydrogen. Waste-to Hydrogen is proposed as a potential solution to provide both sustainable waste management and hydrogen production. Waste-to-Hydrogen (WtH) is a hybrid solution that simultaneously combines sustainable waste management and non-fossil-fuel based hydrogen production. The concept of distributed WtH systems, based on gasification and fermentation, is to support hydrogen fuel cell buses in Glasgow is considered as a potential solution zero emission transport development. Hydrogen has potential to replace petrol and diesel fuels and consequently become part the zero-carbon measures to aid the transition to cleaner energy sources. When hydrogen is produced from renewable or sustainable energy sources it can help decarbonise the energy and transport sector. To be attractive to policymakers and investors it is necessary for the hydrogen from a WtH system to demonstrate its carbon footprint is lower than conventional methods. By supporting the effort to reach carbon emission reduction targets, hydrogen is part of the solution to limit climate change, a global emergency. Providing research to support the roadmap of hydrogen-powered public transport to shape the direction of future technological improvement and policy formulation. As well as the potential to provide a clean versatile fuel through hydrogen, WtH can offer an alternative waste management practice that diverts waste away from landfill and incineration. By utilising and transforming waste into a useful energy resource, a value is applied which can encourage the development of sustainable disposal methods such as WtH conversion processes. Glasgow was chosen as the location for the study due to the large population which would supply regular amounts of waste to be used as feedstock. The city council is also actively trying to decarbonise local industries including transport, this is seen by the strategies and targets in place such as Net Zero by 2045. An aim of this study is to demonstrate how low carbon hydrogen production technologies could fit into the city’s transport and energy plan and support the hydrogen strategy, thereby benefitting the people of Glasgow. Whilst Glasgow does not currently use fuel cell electric buses (FCEB) for public transport, an intention to run a fleet has been presented through the publication of the Scottish Governments Hydrogen Policy Statement (2020) and Hydrogen Action Plan (2022). FCEB fleets in other parts of the UK notably London and Birmingham, have shown the environmental benefit through the annual carbon savings made. FCEBs are classified as zero emissions buses (ZEB) which the UK Department of Transport has stated can reduce carbon emissions by 46 tonnes per year and nitrogen oxide (NOx) by 23kg when compared to a diesel bus (UK Government Department for Transport, 2021). This study contributes to the growing evidence of the benefits of using hydrogen as a transport fuel in terms of the carbon savings as an alternative to conventional fossil fuels. Whilst the main concerns of the underdeveloped industrial status, relatively immature technology and high costs are explored. In practice WtH is currently limited to laboratory and pilot scale systems and requires further investment and policy support for advancements to be made. These bottlenecks and limitations are considered in the discussion section of this study. The research question centres around the economic and environmental feasibility of WtH within Glasgow. A feasible project would show the carbon savings compared to conventional methods in both aspects of waste management and hydrogen production. The feasibility is also a measurement of positive returns on economic investment where total project costs do not outweigh the environmental benefits associated with low carbon technologies. This study critically assesses the current situation for WtH development in terms of the environmental impact and potential carbon savings, economic implications, and cost benefits, plus transport and climate policy. The novelty of the study establishes a procedure for defining how WtH could support the growing hydrogen industry as a low carbon hydrogen production technique. The results from the environmental impact analysis and economic assessment add data sets to existing research in academia and energy industry. Life cycle assessment (LCA), cost benefit analysis (CBA) and multi-bjective optimization (MOO) have been conducted to determine the feasibility of WtH projects to support green transport systems and sustainable waste management schemes. A variety of WtH scenarios were designed based on biomass waste feedstock, hydrogen production reactors, and upstream and downstream system components. The WtH systems selected use thermochemical and biochemical technologies to convert the different waste feedstocks available in Glasgow with suitable operational conditions according to the waste characteristics. The waste considered in this study is biodegradable, carbon based and organic including household, plastics, waste wood products, as well as the wet fraction of waste such as food and sewage sludge. Five scenarios, four WtH technologies and one conventional hydrogen production technology of steam methane reforming (SMR), were designed to allow for comparison of environmental and economic results. The scenarios differ in waste feedstock type and technology leading to differences in hydrogen production rates, hydrogen yields, and process carbon emissions. Waste that is less suitable for thermochemical conversion processes can be utilised by biochemical technology to ensure the most efficient and least energy intensive method is applied. The environmental approach for this work focuses on the LCA method to evaluate environmental performance through the carbon saving potential using global warming potential (GWP) as the impact indicator for the WtH technologies. It was shown that WtH technologies could reduce <55% of CO2-eq emissions per kg H2 compared to SMR. Gasification treating municipal solid waste and waste wood had global warming potentials of 4.99 and 4.11 kg CO2-eq/kg H2 respectively, which were lower than dark fermentation treating wet waste at 6.6 kg CO2-eq/kg H2 and combined dark and photo fermentation at 6.4 kg CO2-eq/kg H2. The distance emissions of WtH-based electric fuel cell bus scenarios were 0.33-0.44 kg CO2-eq/km as compared to 0.89 kg CO2-eq/km for the SMR-based scenario. The economic assessment in this study uses cost benefit analysis to determine whether the carbon savings outweigh the expected cost of a WtH system. The CBA was conducted to compare the economic feasibility of the different WtH systems with the conventional SMR. A database was that includes, direct cost data on construction, maintenance, operations, infrastructure, and storage, along with indirect cost data comprising environmental impacts and externalities, cost of pollution, carbon taxes and subsidies was collated. The results are in the form of economic indicators Net present value (NPV), Internal rate of return (IRR), Benefit cost ratio (BCR) and Levelized cost of hydrogen (LCoH). The LCoH was calculated as 0.49 GBP/kg for the gasification systems using MSW feedstock and 0.52 GBP/kg for waste wood gasification. The LCoH for dark fermentation was calculated to be 0.52 GBP/kg and 0.59 GBP/kg for combined dark and photo fermentation systems. Sensitivity analysis was conducted to identify the most significant influential factors of distributed WtH systems. The results indicate that the conversion efficiency and the energy density of the waste had the largest impact for biochemical technology and thermochemical technologies, respectively. It is concluded that WtH could be economically feasible for hydrogen production in Glasgow. However, limitations including high capital expenditure will require cost reduction through technical advancements and carbon tax on conventional hydrogen production methods to improve the outlook for WtH. The multi-objective optimisation results suggest that optimisation is possible with the best solution calculated to minimise both total cost and GWP for the four Scenarios assessed in this work. The results from the three analysis types in this work, indicate the feasibility of WtH in Glasgow. The results suggest there is potential to utilise the waste generated within Glasgow to produce hydrogen, reduce the environmental impact of waste management practices, and provide economic benefit to both the energy and transport industry

    Composting of distillery spent wash

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    Distillery spent wash, a by-product of the alcoholic beverage industry, is an organic waste whose management poses significant challenges due to its acidity, high organic load, notable content of polyphenols, macronutrients, micronutrients and heavy metals. In Europe, billions of liters of distillery waste are generated annually and its eco-unfriendly disposal can cause severe environmental and health impacts. Composting is a viable management strategy to treat and manage distillery slop promoting the recycling and stabilization of organic matter and nutrients in the material. The review examines different composting methods, such as single composting, co-composting and vermicomposting, along with their benefits and drawbacks. To optimize composting effectiveness, various materials, such as sewage sludge, vinasse, green and animal manure, inorganic amendments, bagasse, filter cake and municipal solid waste, among other agro-food and animal bio-wastes, can be used as a source of nitrogen and microorganisms. Also, the usage of different materials and mixtures aims to enhance the composting process increasing the degradation rate and the quality of the compost. The challenges of distillery spent wash composting are also covered in the paper which are mainly due to its characteristics, including high salt content, low carbon-to-nitrogen ratio, low pH and potential phytotoxicity. The paper concludes that composting distillery spent wash is an effective and sustainable waste management solution for recovering valuable nutrient resources and producing a stable nutrient-rich organic soil amendment. The produced compost can improve crop yields, nutrient absorption by plants and plant biomass and contribute to soil properties and restoration. The review provides insights into the current state of distillery spent wash composting and recommends future research directions to improve efficiency and expand potential applications

    Identifying sources of antibiotic resistance genes in the environment using the microbial Find, Inform, and Test framework

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    Introduction: Antimicrobial resistance (AMR) is an increasing public health concern for humans, animals, and the environment. However, the contributions of spatially distributed sources of AMR in the environment are not well defined. Methods: To identify the sources of environmental AMR, the novel microbial Find, Inform, and Test (FIT) model was applied to a panel of five antibiotic resistance-associated genes (ARGs), namely, erm(B), tet(W), qnrA, sul1, and intI1, quantified from riverbed sediment and surface water from a mixed-use region. Results: A one standard deviation increase in the modeled contributions of elevated AMR from bovine sources or land-applied waste sources [land application of biosolids, sludge, and industrial wastewater (i.e., food processing) and domestic (i.e., municipal and septage)] was associated with 34–80% and 33–77% increases in the relative abundances of the ARGs in riverbed sediment and surface water, respectively. Sources influenced environmental AMR at overland distances of up to 13 km. Discussion: Our study corroborates previous evidence of offsite migration of microbial pollution from bovine sources and newly suggests offsite migration from land-applied waste. With FIT, we estimated the distance-based influence range overland and downstream around sources to model the impact these sources may have on AMR at unsampled sites. This modeling supports targeted monitoring of AMR from sources for future exposure and risk mitigation efforts

    Review of the Valorization Initiatives of Brewing and Distilling Byproducts

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    Beer and spirits are two of the most consumed alcoholic beverages in the world, and their production generates enormous amounts of by-product materials. This ranges from spent grain, spent yeast, spent kieselguhr, trub, carbon dioxide, pot ale, and distilled gin spent botanicals. The present circular economy dynamics and increased awareness on resource use for enhanced sustainable production practices have driven changes and innovations in the management practices and utilisation of these by-products. These include food product development, functional food applications, biotechnological applications, and bioactive compounds extraction. As a result, the brewing and distilling sector of the food and drinks industry is beginning to see a shift from conventional uses of byproducts such as animal feed to more innovative applications. This review paper therefore explored some of these valorization initiatives and the current state of the art

    Sustainability assessment of faecal sludge treatment technologies for resource recovery in Phnom Penh, Cambodia

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    Selection of appropriate sustainable treatment technologies involves satisfying user requirements, quality standards on treatment and products, and specific socio-technical constraints in the intended context. Using locally adapted multi-criteria assessment (MCA), this study investigated faecal sludge treatment technologies that enable resource recovery in Phnom Penh. A four-step structured approach was applied, involving i) identification of available options, ii) prerequisite screening, iii) MCA and iv) stakeholder discussions and ranking. Data were collected in a literature review, stakeholder interviews and an online survey. Lists of suitable primary (n = 7) and secondary (n = 13) treatment technologies were compiled based on the literature. Four secondary treatment technologies (solar drying, co-composting, vermicomposting, black soldier fly larvae (BSFL) composting) were retained after prerequisite screening and subjected to MCA. Co-composting was ranked highest in MCA, since it performed well in multiple aspects, especially for health criteria. However, when economic return on investment was prioritised and a lower treatment class was accepted, e.g. USEPA Class B biosolids, the highest ranking was achieved by vermicomposting or BSFL composting. If institutional criteria were included in the assessment, solar drying would likely be the highest-ranked option, since this simple technology requires less logistically complex stakeholder arrangements than co-composting. These results show that the ranking obtained for different sludge treatment options depends on criteria weighting and tradeoffs. Considering secondary treatment options is crucial during early planning for faecal sludge management in a city of low-and-middle income countries, as the primary treatment must yield appropriate feedstock quality for the secondary treatment step
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