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The Flameless Combustion (FC) regime has been pointed out as a promising combustion technique to lower the emissions of nitrogen oxides (NOx) while maintaining low CO and soot emissions, as well as high efficiencies. However, its accurate modeling remains a challenge. The prediction of pollutant species, especially NOx, is affected by the usually low total values that require higher precision from computational tools, as well as the incorporation of relevant formation pathways within the overall reaction mechanism that are usually neglected. The present work explores a multiple step modeling approach to tackle these issues. Initially, a CFD solution with simplified chemistry is generated [both the Eddy Dissipation Model (EDM) as well as the Flamelet Generated Manifolds (FGM) approach are employed]. Subsequently, its computational cells are clustered to form ideal reactors by user-defined criteria, and the resulting Chemical Reactor Network (CRN) is subsequently solved with a detailed chemical reaction mechanism. The capabilities of the clustering and CRN solving computational tool (AGNES—Automatic Generation of Networks for Emission Simulation) are explored with a test case related to FC. The test case is non-premixed burner based on jet mixing and fueled with CH4 tested for various equivalence ratios. Results show that the prediction of CO emissions was improved significantly with respect to the CFD solution and are in good agreement with the experimental data. As for the NOx emissions, the CRN results were capable of reproducing the non-monotonic behavior with equivalence ratio, which the CFD simulations could not capture. However, the agreement between experimental values and those predicted by CRN for NOx is not fully satisfactory. The clustering criteria employed to generate the CRNs from the CFD solutions were shown to affect the results to a great extent, pointing to future opportunities in improving the multi-step procedure and its application.

Large seaport hubs in Northwestern Europe are aiming to develop as circular hotspots and are striving to become first movers in the circular economy (CE) transition. In order to facilitate their transition, it is therefore relevant to unravel potential patterns of the circular transition that ports are currently undertaking. In this paper, we explore the CE patterns of five Belgian seaports. Based on recent (strategy) documents from port authorities and on in-depth interviews with local port executives, the circular initiatives of these ports are mapped, based on their spatial characteristics and transition focus. The set of initiatives per port indicates its maturity level in terms of transition towards a circular approach. For most studied seaports, an energy recovery focus based on industrial symbiosis initiatives seems to dominate the first stages in the transition process. Most initiatives are not (yet) financially sustainable, and there is a lack of information on potential new business models that ports can adopt in view of a sustainable transition. The analysis of CE patterns in this paper contributes to how ports lift themselves out of the linear lock-in, as it demonstrates that ports may walk a different path and at a diverging speed in their CE transition, but also that the Belgian ports so far have focused too little on their cargo orchestrating role in that change process. Moreover, it offers a first insight into how integrated and sustainable the ports’ CE initiatives currently are.

This paper guides decision making in more sustainable urban water management practices that feed into a circular economy by presenting a novel framework for conceptually designing and strategically planning wastewater treatment processes from a resource recovery perspective. Municipal wastewater cannot any longer be perceived as waste stream because a great variety of technologies are available to recover water, energy, fertilizer, and other valuable products from it. Despite the vast technological recovery possibilities, only a few processes have yet been implemented that deserve the name water resource factory instead of wastewater treatment plant. This transition relies on process designs that are not only technically feasible but also overcome various non-technical bottlenecks. A multidimensional and multidisciplinary approach is needed to design water resource factories (WRFs) in the future that are technically feasible, cost effective, show low environmental impacts, and successfully market recovered resources. To achieve that, the wastewater treatment plant (WWTP) design space needs to be opened up for a variety of expertise that complements the traditional wastewater engineering domain. Implementable WRF processes can only be designed if the current design perspective, which is dominated by the fulfilment of legal effluent qualities and process costs, is extended to include resource recovery as an assessable design objective from an early stage on. Therefore, the framework combines insights and methodologies from different fields and disciplines beyond WWTP design like, e.g., circular economy, industrial process engineering, project management, value chain development, and environmental impact assessment. It supports the transfer of the end-of-waste concept into the wastewater sector as it structures possible resource recovery activities according to clear criteria. This makes recovered resources more likely to fulfil the conditions of the end-of-waste concept and allows the change in their definition from wastes to full-fledged products.

In this paper we suggest considering sustainability as a moral framework based on social justice, which can be used to evaluate technological choices. In order to make sustainability applicable to discussions of nuclear energy production and waste management, we focus on three key ethical questions, namely: (i) what should be sustained; (ii) why should we sustain it; and (iii) for whom should we sustain it. This leads us to conceptualize the notion of sustainability as a set of values, including safety, security, environmental benevolence, resource durability, and economic viability of the technology. The practical usefulness of sustainability as a moral framework is highlighted by demonstrating how it is applicable for understanding intergenerational dilemmas—between present and future generations, but also among different future generations—related to nuclear fuel cycles and radioactive waste management.

Current open data systems lag behind in their promised value creation and sustainability. The objective of the current study is twofold: 1) to investigate whether existing open data systems meet the requirements of open data ecosystems, and 2) to develop a research agenda that discusses the gaps between current open data systems on the one hand and participatory, value-creating, sustainable open data ecosystems on the other hand. The literature reveals that the main characteristics of value-creating, sustainable open data ecosystems are user-drivenness, inclusiveness, circularity, and skill-based. Our comparative case study of five open data systems in various application domains and countries highlighted that none of these systems are real open data ecosystems: they often do not balance open data supply and demand, exclude specific user groups and domains, are linear, and lack skill-training. We elaborate on a research agenda that discusses how research should address the challenge of making open data ecosystems more value-generating and sustainable.

This critical review reveals the technologies and potentials to recover water, energy, fertilizers and products from municipal WWTPs but also analyses the various bottlenecks that may their hinder successful implementation.

The carrying capacity of the planet is being exceeded, and there is an urgent need to bring forward revolutionary approaches, particularly in terms of energy supply, carbon emissions and nitrogen inputs into the biosphere. Hydrogen gas, generated by means of renewable energy through water electrolysis, can be a platform molecule to drive the future bioeconomy and electrification in the 21st century. The potential to use hydrogen gas in microbial metabolic processes is highly versatile, and this opens a broad range of opportunities for novel biotechnological developments and applications. A first approach concerns the central role of hydrogen gas in the production of bio-based building block chemicals using the methane route, thus, bypassing the inherent low economic value of methane towards higher-value products. Second, hydrogen gas can serve as a key carbon-neutral source to produce third-generation proteins, i.e. microbial protein for food applications, whilst simultaneously enabling carbon capture and nutrient recovery, directly at their point of emission. Combining both approaches to deal with the intermittent nature of renewable energy sources maximises the ability for efficient use of renewable resources.