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Treating microbial systems engineering as an inverse function problem to enhance production of biomolecules
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Klebsiella pneumoniae as cell factory for chemicals production
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Microbial engineering of new Streptomyces sp. from extreme environments for novel antibiotics, anticancer and antifungal Drugs
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The run of mine grade is on target but the process plant is underperforming – what’s the problem?
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Assessing social implications of circular economy by integrating circularity in S- LCA
Get PDFEven though circular economy (CE) is crucial for sustainable performance, not all circularity activities are automatically more sustainable as some trade-offs may occur (e.g., major environmental impacts due to intensive processing of wastes or social effects when production/treatment locations change). In the position paper of the Life Cycle Initiative, Peña et al. (2021) stated the importance of combining CE and life cycle approaches to avoid burden shifting. Apart from economic factors, the recent focus of research in CE is on environmental impacts and how to measure them. Sassanelli et al. (2019) identified life cycle assessment (LCA) as the most used tool for assessing environmental consequences of CE. To ensure that circularity holistically contributes to sustainable behavior, besides economic and environmental aspects, also the third pillar of sustainability, namely social aspects, must be considered. However, Kirchherr, Reike and Hekkert (2017) found that research on social impacts resulting from a shift from a linear to a circular economy is still lacking. Thus, aim of this research is to identify social implications of circular economy and to investigate in what manner circularity aspects currently are assessed in social life cycle assessment (S-LCA). The research starts with a literature review on social consequences of CE. As CE mostly replaces former linear business models, the research includes identifying affected stakeholders in both the former linear and new circular strategies. Based on this analysis, the identified implications will be linked to the relevant stakeholders and S-LCA subcategories. Adequate indicators for assessing the social performance of CE strategies will be proposed referring to indicators presented in the Methodological Sheets for Subcategories in Social Life Cycle Assessment (S-LCA) 2021 but also by identifying relevant new indicators that cover social implications of CE that are not covered by existing indicators. Moreover, further CE indicators that should be considered to link circularity performance and S-LCA will be proposed. Hence, a combination of indicators will be presented that will outline how circularity, for example, influences regional employment, cultural changes, education, and other social aspects.
Kirchherr, J., Reike, D. and Hekkert, M. (2017) ‘Conceptualizing the circular economy: An analysis of 114 definitions’, Resources, Conservation and Recycling, 127(April), pp. 221–232. doi: 10.1016/j.resconrec.2017.09.005.
Peña, C. et al. (2021) ‘Using life cycle assessment to achieve a circular economy’, International Journal of Life Cycle Assessment. Springer Berlin Heidelberg, 26(2), pp. 215–220. doi: 10.1007/s11367-020-01856-z.
Sassanelli, C. et al. (2019) ‘Circular economy performance assessment methods: A systematic literature review’, Journal of Cleaner Production. Elsevier Ltd, 229, pp. 440–453. doi: 10.1016/j.jclepro.2019.05.019
Environmental assessment of different integrated biorefinery scenarios using walnut shells as a source for lignin production
Get PDFNowadays, the waste or loss of food produced along the supply chain is equivalent to approximately 33% of the total (FAO, 2013). However, the food sector can also contribute to solving the environmental problems it generates. The valorisation of food waste, with the aim of obtaining value-added compounds, represents a paradigm challenge within the framework of sustainable development. One of the products of high added value of greatest interest to the scientific community is lignin, due to its use as a source for obtaining chemical products. These lignin-based compounds must be competitive with petroleum derivatives from an economic and environmental aspect (Fernández-Rodríguez et al., 2021). In recent years, soda and organosolv processes have been placed at the centre of the biomass fractionation process spectrum. These processes make it possible to solubilise the lignin without altering its initial structure to any great extent (Fernández-Rodríguez et al., 2021). In the walnut processing industry, large quantities of shells are produced as by-products (approximately 400g per kilo of processed walnuts) which are either discarded or burned as fuel (Jahanban- Esfahlan et al., 2020). Nevertheless, under a circular economy approach, these wastes can be valorised to obtain lignin, due to their high lignin content by mass (approximately 40% of the total) (Jahanban-Esfahlan et al., 2020). Therefore, this study aims to environmentally analyse two different sequences of lignin extraction through the valorisation of walnut shells, considering the Life Cycle Assessment methodology. Lignin production involves the following steps: autohydrolysis, delignification, solid cleaning and precipitation. In the organosolv process, an ethanol/water mixture (70/30, v/v) is used at 200°C in a solid/liquid ratio of 1:6 while the soda process is carried out at 121°C using a 7.5% NaOH solution by weight as reagent in the same solid/liquid ratio as in the organosolv method (Fernández-Rodríguez et al., 2021). The valorisation system based was simulated with the use of Aspen Plus® software (Aspentech, 2020) and 100 kg of walnut shells were taken as the biomass input stream. The environmental study considered one kilogram of lignin as the target product, under a cradle-to-gate approach. The inventory is based on data taken from the simulation software. The environmental results suggest that the scenario based on the organosolv process presents the worst environmental profile for all impact categories mainly due to the total thermal energy required in the plant, requiring approximately five times more energy in this scenario than in the soda scenario. In addition, it is observed that the main equipment consuming the most thermal energy is the distillation column at the final stage of the valorisation process to recover the solvent for recirculation and the equipment for heating the large quantities of water needed in the autohydrolysis stage. As future work, it is proposed to reuse the internal streams of the valorisation plant to reduce the loads generated by the energy requirement as well as the use of renewable energy sources instead of using the national energy grid. -Aspentech, 2020. Aspen Plus. URL https://www.aspentech.com/products/engineering/aspen-plus/ (accessed 3.31.20). -FAO, 2013. Food wastage footprint: Impacts on natural resources - Summary report. -Fernández-Rodríguez, J., Erdocia, X., Alriols, M.G., Labidi, J., 2021. Techno-economic analysis of different integrated biorefinery scenarios using lignocellulosic waste streams as source for phenolic alcohols production. J. Clean. Prod. 285. https://doi.org/10.1016/j.jclepro.2020.124829 -Jahanban-Esfahlan, A., Jahanban-Esfahlan, R., Tabibiazar, M., Roufegarinejad, L., Amarowicz, R., 2020. Recent advances in the use of walnut (: Juglans regia L.) shell as a valuable plant-based bio-sorbent for the removal of hazardous materials. RSC Adv. 10, 7026–7047. https://doi.org/10.1039/c9ra10084
Climate change impact of the development in household waste management in China
Get PDFChina has experienced significant economic growth over the last few decades – as reflected in the amount of municipal solid waste the country generates. According to national annual data, the quantity of municipal solid waste increased from 148 million tons in 2006 to 235 million tons in 2020. In 2006, 81% of municipal solid waste was landfilled, 15% was incinerated and 4% biologically treated. In contrast, in 2020, 33% of municipal solid waste was landfilled, 62% was incinerated and 5% biologically treated. LCA modelling shows that the current development away from landfilling and towards incineration with energy recovery is beneficial with respect to climate change. Landfilling is a net load with respect to climate change: The methane slip from the degradation of the food waste is high (39%, resulting in around 250 kg CO2-eq/ton wet household waste) but even though carbon sequestration of the residual waste in the landfill is a saving (around 100 kg CO2-eq/ton wet household waste), the net value is a high load. Incinerating all the household waste is a small net saving with respect to climate change. However, the net value is the difference between a very large load and a very large saving (both around 400 kg CO2-eq/ton wet household waste).The load is from incineration of plastic and the saving is from recovered electricity substituting for fossil-based electricity. Any uncertainty related to one or both of these numbers easily could affect the net value. This also shows a potential for improvement, if the waste contained less plastic or more electricity could be recovered. Source-separation of the food waste at the current 20% rate contributes with additional savings of about 5-10 kg CO2-eq/ton wet household waste. Here recovery of the oil fraction and producing electricity from biogas is the better way of biorefining. However, the difference is very small. Variations in household waste composition, due to current geographical variations or due to future consumption patterns, illustrated with four different waste compositions, add variation to the net results of the order of 40 kg CO2-eq/ton wet household waste as illustrated for a technological configuration of incineration and biorefining of 20% collected food waste. However, this variation does not challenge the conclusion that incineration is better than landfilling with the current recovery and substitution of electricity. Increasing the source-sorting efficiency of the food waste, for example from the current 20% to 60%, which we consider very high, provides an additional saving of 20 kg CO2-eq/ton wet household waste. This may seem a small benefit of a large effort. As China implements increasing use of renewable energy sources, the exchange of energy between the waste system and the energy system may change. It is impossible to predict what the long-term marginal technology will be and when the long-term marginal technology will change. Fossil-based energy sources could be the affected marginal if implementation of renewable energy sources cannot meet the needs in the market, but one day renewable energy sources may become the affected marginal. Our results then reveal a completely different picture: Incineration has much higher loads than landfilling with respect to climate change. This is due to the fact that the recovery of energy provides very low savings in climate change impacts. This does not indicate that landfills again become attractive from a climate change of view, because of the methane issue. With the urgency of climate mitigation, a 20-year perspective on methane reveals very high climate change impacts from landfilling. The results, however, stress the importance of considering how to reduce the direct load from incineration. There are three options: Use bioplastic instead of fossil-based plastic, recycling of plastic instead of incineration, or introduce carbon capture and storage to remove carbon dioxide from the flue gas. While the two first options will reduce the load from incineration, carbon capture and storage may make incineration a net saving. These issue must be specifically assessed, but our results show that although the current development in Chinese household waste management is contributing to reduce climate change, new challenges must be addressed as the energy system change to renewable energy sources
Analysis of plastic waste circularity through LCA
Get PDFUpcycling processes are better aligned with the Circular Economy model, which defends that the plastic waste is a valuable resource with the potential to be recirculated in a new material cycle. To ensure the highest number of cycles, products, components and material should be kept at their highest utility and value (Webster, 2017). However, this is not what is happening in the recycling sector because upcycling processes are more complex, and energy and resource-intensive. As a result, the environmental benefits of plastic upcycling are frequently called into question and downcycling methods are implemented owing to their lower complexity and costs, regardless of the irreversible and meaningful loss of quality. In this work, three plastic waste management scenarios have been assessed to determine their potential to contribute to the implementation of the Circular Economy. The chosen waste treatment methods are upcycling of plastic scrap through deinking technology, downcycling by re-extrusion and, finally, incineration. The environmental impacts have been computed through LCA methodology. The results show that depending on the assumptions made, LCA can lead to conclusions which are opposite to the Circular Economy principles, thus favouring the downcycling and incineration of plastic waste with high potential to be recirculated. Therefore, to make a fairer comparison between upcycling and other waste treatment options, two modifications have been suggested. First, the target market for recycled pellets should be included in the computation since it is reliant on the material´s quality. Downcycled dark pellets can be used in applications which cover 24% of the total market. Conversely, upcycled pellets can reach 100% of the market. And second, the energy produced during incineration cannot substitute the energy from fossil fuels. The heating value of plastics is usually higher than the energy consumed during raw pellets production. Therefore, recycling will be always seen as the least favourable option. Nevertheless, according to the Circular Economy principles, the energy has to come from renewable sources. Therefore, if our society is moving forward to this new model, fossil fuels should not be considered. Finally, it has been demonstrated that increasing the quality of recycled plastics through upcycling processes is more beneficial than increasing the recycling rates. This is to say that recycle more is good, but what is needed is to recycle better. This work is aligned with two of the conference topics: LCA of municipal and industrial waste management scenarios. LCA of the management of specific waste streams in a circular economy perspective. Reference: Webster, K., 2017. The circular economy: A wealth of flows. Ellen MacArthur Foundation Publishin
Life Cycle Assessment of Multi-Loop Recycling: Opportunities and Challenges
Get PDFToday, circular economy plays a prominent role in optimization of natural resource consumption, while also minimizing waste generation throughout the life cycle of a product. Both in relation to climate targets, the UN Sustainability Development Goals, as well as simply meeting recycling targets at national level. Keeping products, materials and resources in subsequent production cycles, for as long as possible, is one of the fundamental concepts of circular economy, and consistent strategies for how to improve resource utilization throughout the life cycle(s) of products are needed. Regarding the end-of-life waste stage of the product cycle, this can be achieved by reusing, repairing and recycling waste materials. However, within waste management most focus has been simply on recycling with little reflection of the material loops in a longer time perspective. Therefore, to avoid implementation of circular economy initiatives that may lead to net environmental impacts rather than benefits, comprehensive and systemic assessments are needed also involving subsequent recycling loops. While life cycle assessment (LCA) of repairing, reuse, recycling, and utilization options have been provided in literature, little attention has been placed on cascading and multiple recycling loops, although this is one of the primary intentions behind circular economy.
This study provides preliminary results evaluating LCA approaches from the perspective of multi-loop and cascading recycling with the aim of identifying opportunities, limitations and challenges based on current literature. Recommendations are provided based on evaluation of simple cases