Direct membrane filtration (DMF) of municipal wastewater offers an alternative solution for centralized and decentralized wastewater treatment in Iceland. The efficiency of biologicalbased wastewater treatment is restricted in Iceland, due to low temperatures and high wastewater inflow rates with extremely low concentration of organics. This study aims to investigate membrane fouling mechanisms and mitigation approaches during DMF of municipal wastewater. The DMF experiments were performed using a crossflow flat sheet membrane filtration cell integrated with an optical coherence tomography (OCT) imaging system. The effects of membrane material, operation conditions and cleaning protocol on DMF performance and foulant composition were examined. The threshold flux testing results indicated that a PVDF membrane (0.08 μm) was suitable for DMF of wastewater. Increasing crossflow velocity, physical flushing frequency and flushing water temperature contributed greatly to mitigate fouling. During a continuous DMF process, reversible fouling was predominant, while during intermittent DMF with periodical physical cleaning, irreversible/ irremovable fouling was dominant. A possible shift of tightly attached cake layer to irreversible/ irremovable fouling was revealed by the direct observation of fouling via OCT. The foulants autopsy indicated that a combination of organic and inorganic foulants was attributed to membrane fouling, instead of biological fouling. Under the optimized filtration condition, sustainable long-term DMF operation (~230 h) was achieved by employing a combination of periodical physical flushing with chemical-enhanced flushing. The water quality analysis showed that the DMF process could efficiently remove solids and greater-sized soluble organics, allowing the treated water to meet wastewater discharge standards.
Multiple stakeholders with a wide range of objectives are engaged in a port system. Ports themselves are faced with many uncertainties in this volatile world. To meet stakeholder objectives and deal with uncertainties, adaptive port planning is increasingly being acknowledged. This method offers robust planning, and thereby, a sustainable and flexible port may be developed. The planning process starts with defining success in terms of the specific objectives of stakeholders during the projected lifetime of the port. In the present work, an integrated framework to reach a consensus on the definition of success, involving stakeholders with different influences, stakes and objectives, is presented. The framework synthesises the problem structuring method with stakeholder analysis and combines these with fuzzy logic to support decision-makers in formulating a definition of success in the planning process. Our framework is applied to the Port of Isafjordur, the third busiest port of call for cruise ships in Iceland. Values of stakeholders about port planning were structured around the value-focussed thinking method to identify stakeholder objectives. The highest level of agreement on the objectives, which is viewed here as success in port planning, was revealed by the fuzzy multi-attribute group decisionmaking method. Success was defined, prioritising an increase in competitiveness among other planning objectives, such as effective and efficient use of land, increasing safety and security, increasing hinterland connectivity, increasing financial performance, better environmental implications, flexibility creation and increasing positive economic and social impacts.
Purpose Port throughput analysis is a challenging task, as it consists of intertwined interactions between a variety of cargos and numerous influencing factors. This study aims to propose a quantitative method to facilitate port throughput analysis by identification of important cargos and key macroeconomic variables. Design/methodology/approach Mutual information is applied to measure the linear and nonlinear correlation among variables. The method gives a unique measure of dependence between two variables by quantifying the amount of information held in one variable through another variable. Findings This study uses the mutual information to the Port of Isafjordur in Iceland to underpin the port throughput analysis. The results show that marine products are the main export cargo, whereas most imports are fuel oil, industrial materials and marine product. The aggregation of these cargos, handled in the port, meaningfully determines the non-containerized port throughput. The relation between non-containerized export and the national gross domestic product (GDP) is relatively high. However, non-containerized import is mostly related to the world GDP. The non-containerized throughput shows a strong relation to the national GDP. Furthermore, the results reveal that the volume of national export trade is the key influencing macroeconomic variable to the containerized throughput. Originality/value Application of the mutual information in port throughput analysis effectively reduces epistemic uncertainty in the identification of important cargos and key influencing macroeconomic variables. Thus, it increases the reliability of the port throughput forecast.
Capacity plays a crucial role in a port's competitive position and the growth of its market share. An investment decision to provide new port capacity should be supported by a growing demand for port services. However, port demand is volatile and uncertain in an increasingly competitive market environment. Also, forecasting models themselves are associated with epistemic uncertainty due to model and parameter uncertainties. This paper applies a Bayesian statistical method to forecast the annual throughput of the multipurpose Port of Isafjordur in Iceland. Model uncertainties are thus taken into account, while parameter uncertainties are handled by selecting influencing macroeconomic variables based on mutual information analysis. The presented model has an adaptive capability as new information becomes available. Our method results in a range of port throughput forecasts, in addition to a point estimate, and it also accounts for epistemic uncertainty, thus increasing the reliability of forecasts. Our results provide support for informed decision-making in capacity planning and management. Our forecasts show a constant linear growth of containerized throughput the period 2020-2025. Noncontainerized throughput declines rapidly over the same period.
Ports have always been evolving to satisfy the new or changing demands of stakeholders. In this unstable world, ports as dynamic systems are developed under a high degree of uncertainty. Furthermore, black-swan events, for instance, the financial crisis in 2008, the avalanche in Flateyri (Iceland) in 2020, the COVID-19 pandemic in 2020-2021 make successful port planning a challenging task. Indeed, the ever-increasing complexity of a port system and its long technical lifetime make uncertainty considerations inevitable in the planning process. Therefore, this research presents a structured framework to deal with uncertainties, including opportunities and vulnerabilities, in the port planning process. To this end, a structured stakeholder analysis is performed to effectively and timely engage stakeholders in the planning process. Fuzzy logic 3-dimensional decision surface is used to identify the salient stakeholders. Subsequently, the success of the future port is defined in terms of the specific objectives of the stakeholders. To develop this definition, a problem structuring method and fuzzy multi-attribute group decision-making method are synthesized. Then, a port throughput forecast is conducted that accounts for epistemic uncertainty, including model and parameters uncertainties, and thus increases the reliability of forecast results. The method identifies the influencing macroeconomic variables on port throughput by mutual information and then applies the Bayesian statistical method to forecast the port throughput. Effective actions are planned to seize opportunities and manage vulnerabilities that manifest in the projected lifetime. Therefore, the port can adapt or better withstand the vagaries of the future. The nonlinearity of dealing with uncertainty by application of the framework provides a robust and better plan toward its success. The framework supports decision making under uncertainty and facilitates adaptive port planning. The framework is applied to the Ports of Isafjordur Network in Iceland. The results indicate that the uncertainties mainly present opportunities in the short-time horizon, while in the middle-time horizon the port network is confronted with multiple vulnerabilities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.