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At least 1,441 records · Page 80
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DOE OSTI2016

Large-scale optimization-based non-negative computational framework for diffusion equations: Parallel implementation and performance studies

It is well-known that the standard Galerkin formulation, which is often the formulation of choice under the finite element method for solving self-adjoint diffusion equations, does not meet maximum principles and the non-negative constraint for anisotropic diffusion equations. Recently, optimization-based methodologies that satisfy maximum principles and the non-negative constraint for steady-state and transient diffusion-type equations have been proposed. To date, these methodologies have been tested only on small-scale academic problems. The purpose of this paper is to systematically study the performance of the non-negative methodology in the context of high performance computing (HPC). PETSc and TAO libraries are, respectively, used for the parallel environment and optimization solvers. For large-scale problems, it is important for computational scientists to understand the computational performance of current algorithms available in these scientific libraries. The numerical experiments are conducted on the state-of-the-art HPC systems, and a single-core performance model is used to better characterize the efficiency of the solvers. Furthermore, our studies indicate that the proposed non-negative computational framework for diffusion-type equations exhibits excellent strong scaling for real-world large-scale problems.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Production, Characterization and Bioemulsifying Activity of an Exopolysaccharide Produced by Sphingomonas sp. Isolated from Freshwater

This study aimed to evaluate the emulsion stability of solutions containing exopolysaccharide and culture medium of a Sphingomonas sp. strain with various hydrophobic compounds. The exopolysaccharide characterized belongs to a sphingan group, however, not being a gellan gum as produced by certain Sphingomonas strains. In general, the emulsifying indexes found in this study were above 70% for gasoline, hexane, kerosene and used frying oil. Nonetheless, the best results were achieved in kerosene solutions, which showed an index of 80% after 24 h, remaining stable for more than 168 h in combinations with various EPS concentrations. Interestingly, diesel oil best results were singly achieved in solution pH of 11, showing an index of around 65%. Furthermore, hexane obtained an index of 100% after 24 h when culture medium was used. Thus, these findings highlight the use of EPS as a potential bioemulsifier agent to enhance hydrocarbon degradation and emulsification effects in environmental biotechnology.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Biodegradable Polymer Composites as Coating Materials for Granular Fertilizers

The composites consisting of poly(vinyl alcohol), horn meal, rapeseed cake, glycerol and phosphogypsum were proposed for the encapsulation of mineral fertilizers. Poly(vinyl alcohol) was used as a binder. The other components making ca. 70% of the mass of the composites were waste materials or by-products. They contain phosphorus, nitrogen, calcium, potassium and sulphur, which are useful nutrients for plants. The effect of the amount of glycerol and of the composition of the mixture of the fillers on the mechanical, sorption properties, water vapour permeability, solubility in water, dimensional stability of the composite films was studied. The addition of phosphogypsum and increase of the concentration of glycerol in the composites lead to the decrease of the tensile strength, water vapour permeability and to the increase of elongation at break and of the solubility of the composite films in water. The composites prepared were used for encapsulation of fertilizers. It was established that encapsulation resulted in the increase of the time of release of the fertilizers. In addition, encapsulation improved mechanical properties of the fertilizers. The fertilizer granules were coated with composite films and tested in the cultivation of tomato sprouts. They showed considerable positive effect on the development of the roots of the plants.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

A Decentralized Bi-Level Fuzzy Two-Stage Decision Model for Flood Management

Flood, as a serious worldwide environment problem, can lead to detrimental economic losses and fatalities. Effective flood control is desired to mitigate the adverse impacts of flooding and the associated flood risk through development of cost-effective and efficient flood management decisions and policies. A bi-level fuzzy two-stage stochastic programming model, named BIFS model is developed in this study to provide decision support for economic analysis of flood management. The BIFS model is capable of not only addressing the sequential decision making issue involving the two-level decision makers, but also correcting the pre-regulated flood management decisions before the occurrence of a flood event in the two-stage environment. The probabilistic and non-probabilistic uncertainties expressed as probability density functions and fuzzy sets are quantitatively analyzed. The overall satisfaction solution is obtained for meeting the goals of the two-level decision makers by compromising, reflecting the tradeoffs among various decision makers in the two decision-making levels. The results of application of the BIFS model to a representative case study indicate informed decision strategies for flood management. Tradeoffs between economic objectives and uncertainty-averse attitudes of decision makers are quantified.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Integrated Modeling Approach for Optimal Management of Water, Energy and Food Security Nexus

We report that water, energy and food (WEF) are inextricably interrelated. Effective planning and management of limited WEF resources to meet current and future socioeconomic demands for sustainable development is challenging. WEF production/delivery may also produce environmental impacts; as a result, green-house-gas emission control will impact WEF nexus management as well. Nexus management for WEF security necessitates integrated tools for predictive analysis that are capable of identifying the tradeoffs among various sectors, generating cost-effective planning and management strategies and policies. To address these needs, we have developed an integrated model analysis framework and tool called WEFO. WEFO provides a multi-period socioeconomic model for predicting how to satisfy WEF demands based on model inputs representing productions costs, socioeconomic demands, and environmental controls. WEFO is applied to quantitatively analyze the interrelationships and trade-offs among system components including energy supply, electricity generation, water supply-demand, food production as well as mitigation of environmental impacts. WEFO is demonstrated to solve a hypothetical nexus management problem consistent with real-world management scenarios. Model parameters are analyzed using global sensitivity analysis and their effects on total system cost are quantified. Lastly, the obtained results demonstrate how these types of analyses can be helpful for decision-makers and stakeholders to make cost-effective decisions for optimal WEF management.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

Energy-Water Nexus: Balancing the Tradeoffs between Two-Level Decision Makers

Energy-water nexus has substantially increased importance in the recent years. Synergistic approaches based on systems-analysis and mathematical models are critical for helping decision makers better understand the interrelationships and tradeoffs between energy and water. In energywater nexus management, various decision makers with different goals and preferences, which are often conflicting, are involved. These decision makers may have different controlling power over the management objectives and the decisions. They make decisions sequentially from the upper level to the lower level, challenging decision making in energy-water nexus. In order to address such planning issues, a bi-level decision model is developed, which improves upon the existing studies by integration of bi-level programming into energy-water nexus management. The developed model represents a methodological contribution to the challenge of sequential decisionmaking in energy-water nexus through provision of an integrated modeling framework/tool. An interactive fuzzy optimization methodology is introduced to seek a satisfactory solution to meet the overall satisfaction of the two-level decision makers. The tradeoffs between the two-level decision makers in energy-water nexus management are effectively addressed and quantified. Application of the proposed model to a synthetic example problem has demonstrated its applicability in practical energy-water nexus management. Optimal solutions for electricity generation, fuel supply, water supply including groundwater, surface water and recycled water, capacity expansion of the power plants, and GHG emission control are generated. In conclusion, these analyses are capable of helping decision makers or stakeholders adjust their tolerances to make informed decisions to achieve the overall satisfaction of energy-water nexus management where bi-level sequential decision making process is involved.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Solubility of U(VI) in chloride solutions. II. The stable oxides/hydroxides in alkaline KCl solutions: Thermodynamic description and relevance in cementitious systems

In this study, the solubility of U(VI) is investigated from undersaturation conditions in 0.1, 0.51, 1.03, 3.31 and 4.58 m KCl–KOH solutions at pHm = 7.5–14.6 (with pH m = –log [H + ] in molal units). All experiments were performed under Ar atmosphere at T = (22 ± 2)°C. XRD, quantitative chemical analysis, SEM–EDS and TG–DTA confirm that K 2 U 2 O 7 ·1.5H 2 O(cr) is the solid phase controlling the solubility in all evaluated systems at pH m ≥ 9.5. Below this pH m and with decreasing KCl concentration, the formation of sub-stoichiometric phases with K:U < 1 is indicated by XRD and solubility data. The concentration of uranium in equilibrium with K 2 U 2 O 7 ·1.5H 2 O(cr) shows a pH-independent behaviour up to pH m ≈ 11 regardless of ionic strength, whereas an increase of the solubility with a well–defined slope of +1 (log [U] vs. pH m ) is observed at pH m ≥11. These results are consistent with the predominance of UO 2 (OH) 3 – and UO 2 (OH) 4 2- species as previously reported in the literature. The combination of solubility data obtained in the present study with K 2 U 2 O 7 ·1.5H 2 O(cr) and the U(VI) hydrolysis scheme reported in Altmaier et al. (2017) yields a solubility product of log *K° s ,0{0.5K 2 U 2 O 7 ·1.5H 2 O(cr)} = (12.0 ± 0.2). SIT ion interaction coefficients for UO 2 (OH) 3 – and UO 2 (OH) 4 2- with K + are derived based on the newly generated experimental data in dilute to concentrated KCl systems and analogy with NaCl systems. This work extends the thermodynamic database available for U(VI) and allows more accurate source term calculations in the context of nuclear waste disposal under boundary conditions where significant K concentrations may be present and redox conditions lie in the stability field of U(VI). Finally, the K 2 U 2 O 7 ·1.5H 2 O(cr) solid phase can be considered to control the solubility of U(VI) in the degradation phase I of cement and cementitious materials.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Impact of nitrate on the redox chemistry and solubility of Tc(IV) in alkaline, dilute to concentrated aqueous NaCl solutions

Here, the impact of nitrate on the redox behaviour and solubility of 99 Tc(IV) was investigated in 0.1–5.0 M NaCl–NaNO 3 –NaOH solutions with 0.1 M ≤ [NO 3 – ] ≤ 1.0 M and 8.5 ≤ pH m ≤ 14.5 (with pH m = –log [H + ]) in the presence or absence of reducing agents (as Fe powder, Na 2 S 2 O 4 , Sn(II)). The evolution of the redox conditions as a function of time (for t ≤ 450 days) was investigated: (i) in the absence of technetium (inactive samples), (ii) in the presence of 99 Tc(IV) (added as 1–2 mg of TcO 2 ∙0.6H 2 O(am)), and (iii) in the presence of 137 Cs(I) (and absence of 99 Tc). All experiments were conducted in an Ar-glovebox (O 2 < 1 ppm) at T = (22 ± 2) °C. An improved understanding of Tc redox processes in nitrate-rich alkaline solutions is relevant to predict Tc behaviour in specific nuclear waste disposal scenarios and a topic of fundamental scientific interest.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Fate and transport of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and its degradation products in sedimentary and volcanic rocks, Los Alamos, New Mexico

High-explosive compounds including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were used extensively in weapons research and testing at Los Alamos National Laboratory (LANL). Liquid effluents containing RDX were released to an outfall pond that flowed to Cañon de Valle at LANL's Technical Area 16 (TA-16), resulting in the contamination of the alluvial, intermediate and regional groundwater bodies. Monitoring of groundwater within Cañon de Valle has shown persistent RDX in the intermediate perched zone located between 225 and 311 m below ground surface. Monitoring data also show detectable levels of RDX putative anaerobic degradation products. Batch and column experiments were conducted to determine the extent of adsorption-desorption and transport of RDX and its degradation products (MNX, DNX, and TNX) in major rock types that are within the RDX plume. All experiments in this paper were performed in the dark using water obtained from a well located at the center of the plume, which is fairly oxic and has a neutral pH of 7.5. Retardation factors and partitioning coefficient (K d ) values for RDX were calculated from batch experiments. Additionally, retardation factors and K d values for RDX and its degradation products were calibrated from column experiments using a one-dimensional transport model with equilibrium sorption (linear isotherm). Results from the column and batch experiments showed little to no sorption of RDX to the aquifer materials tested, with retardation factors ranging from 1.0 to 1.8 and K d values varying from 0 to 0.70 L/kg. Finally, results also showed no measurable differences between the transport properties of RDX and its degradation products.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Can disposable masks be worn more than once?

Disposable facemasks are a primary tool to prevent the transmission of SARS-COV-2 during the COVID-19 pandemic. However, plastic waste generated from their disposal represents a significant environmental problem that can be reduced by maximizing the service life of disposable masks. We evaluated the effect of repeated wearing on the fitted filtration efficiency (FFE) of N95, KF94, KN95, and procedure/surgical masks. The FFEs of masks were compared following extended wearing with and without washing. Results reveal that most disposable facemasks can retain a high level of their baseline FFE after extended wearing, even after 40 h of wearing. Laundering disposable masks degraded FFE in some instances. We conclude that the durability of disposable facemask performance is considerably longer than their intended single use indication, suggesting that reusing disposable masks is a safe means of reducing plastic waste in the environment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Strategic environmental assessment (SEA) for wind energy planning: Lessons from the United Kingdom and Germany

This paper reports on SEA applied in the wind energy sector in the UK and Germany. Based on a review of 18 SEAs, it is found that the quality of SEA documentation is variable, with over a third of them being deemed unsatisfactory. Furthermore, SEA processes are conducted to varying degrees of effectiveness, with scoping a strength but impact prediction and mitigation weaknesses. Generally speaking, the influence of SEA on German wind energy plan making was found to be low and the influence of SEA on UK plans deemed to be moderate. The German plans had a low influence mainly because of a perceived high environmental performance of the underlying plans in the first instance. Substantive outcomes of SEA are not always clear and the influence of SEA on decision making is said to be limited in many cases. Finally, a lack of effective tiering between SEA and project level EIA is also observed. In addition, our findings echo some of the weaknesses of SEA practice found in previous studies of SEA effectiveness, including poor impact prediction and significance sections and a lack of detailed monitoring programmes for post plan implementation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Sustainability on the urban scale: Proposal of a structure of indicators for the Spanish context

Some efforts to assess sustainability on the urban scale have been made and different tools for measuring the impact on and caused by cities have emerged. However, the sustainability concept varies from region to region, and indicators to measure it should be suitable for the context-specific conditions of the region under study. After doing a comprehensive review of the indicators included in 13 tools developed to assess urban sustainability of cities, this article proposes a new structure of indicators adapted to a Mediterranean city in Spain. The proposed structure is based on a two-level scheme that consists in 14 categories and 63 subcategories, which agglutinate urban sustainability indicators according to their purpose. This structure suggests a set of comprehensible qualitative and quantitative indicators that are easily applicable on neighbourhood or city scales. Given the similar features of Mediterranean countries in terms of environmental and socio-economic aspects, the proposed structure could be extrapolated to other countries with climatic and cultural similarities. Otherwise, the system is a useful tool in the decision-making process to help the different stakeholders involved in new urban developments and regeneration projects in existing neighbourhoods, such as developers, urban planners and public administrations. - Highlights: • Comprehensive review of 13 urban sustainability assessment tools • Proposal of a two-level structure to cluster urban sustainability indicators • Inclusion of sustainability criteria for urban planning projects and interventions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Analysis of the Environmental Impact Assessment (EIA) Directive and the EIA decision in Turkey

The Environmental Impact Assessment (EIA) Directive first entered into force in the United States in 1969, and began to be implemented in many other countries by 1990. The first Environmental Impact Assessment (EIA) Directive in Turkey was published on February 7, 1993, under the Environmental Law No. 2872. The EIA Directive was revised seven times on June 23, 1997, June 6, 2002, December 16, 2003, July 17, 2008, October 3, 2013, and November 25, 2014. Several amendments were made during this process. The first EIA Directive dated 1993 was narrow in scope and its procedure was long, while the amendments in 2003, 2008, 2013, and 2014 widened the scope of the EIA, and shortened the EIA assessment procedures. In this study, the amendments to the Turkish EIA Directive were analysed, and their effect on the number of EIA decisions made was addressed. It was concluded that the uncertainties in EIA procedures were removed, procedures were shortened, and as a result, the number of EIA decisions increased thanks to the revisions made in line with harmonisation with European Union (EU) acquis. - Highlights: • Demonstrates the Environmental Impact Assessment practices in Turkey. • Demonstrates the application of the EIA in Turkey by sector. • Demonstrates the amendments of the EIA by-laws in Turkey. • Demonstrates the changes in EIA practices and EIA decisions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

A method to assess social sustainability of capture fisheries: An application to a Norwegian trawler

Social sustainability assessment of capture fisheries is, both in terms of method development and measurement, not well developed. The objective of this study, therefore, was to develop a method consisting of indicators and rubrics (i.e. categories that articulate levels of performance) to assess social sustainability of capture fisheries. This method was applied to a Norwegian trawler that targets cod and haddock in the northeast Atlantic. Based on previous research, 13 social sustainability issues were selected. To measure the state of these issues, 17 process and outcome indicators were determined. To interpret indicator values, rubrics were developed for each indicator, using standards set by international conventions or data retrieved from national statistics, industry agreements or scientific publications that explore rubric scales. The indicators and rubrics were subsequently used in a social sustainability assessment of a Norwegian trawler. This assessment indicated that overall, social sustainability of this trawler is relatively high, with high rubric scores, for example, for worker safety, provisions aboard for the crew and companies' salary levels. The assessment also indicated that the trawler could improve on healthy working environment, product freshness and fish welfare during capture. This application demonstrated that our method provides insight into social sustainability at the level of the vessel and can be used to identify potential room for improvement. This method is also promising for social sustainability assessment of other capture fisheries. - Highlights: • A method was developed for social sustainability assessment of capture fisheries. • This method entailed determining outcome and process indicators for important issues. • To interpret indicator values, a rubric was developed for each indicator. • Use of this method gives insight into social sustainability and improvement options. • This method is promising for social sustainability assessment of capture fisheries.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Advancing practice relating to SEA alternatives

Developing and assessing alternatives is a key and central stage to Strategic Environmental Assessment (SEA). However, research has repeatedly reported this stage as one of the most poorly undertaken aspects of the SEA process. Current practice limitations include belated consideration of reasonable alternatives, narrow scope of alternatives that often include unrealistic or retrofitted options, limited stakeholder and public involvement in their identification, assessment and selection, lack of systematic approaches to their assessment and comparison, and inadequate reporting of the ‘storyline’ on how they were identified, what the potential impacts are and why the preferred alternative was selected. These issues have resulted in objections and judicial reviews. On the positive side, a number of good practice case studies enable extraction of key lessons and formulation of a set of general recommendations to advance practice in SEA alternatives. In this paper, practical guidance on the identification and development of alternatives, their assessment and comparison, selection of the preferred option, and documentation of the process and the reasons for selection is provided and discussed to frame good practice approaches. - Highlights: • Alternatives are one of the most poorly completed aspects of Strategic Environmental Assessment. • Current practice limitations need to be addressed to enhance SEA effectiveness. • A set of recommendations are extracted from good practice case studies. • These recommendations can be applied across jurisdictions and sectors and tailored as necessary.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Multicriteria cost–benefit assessment of tannery production: The need for breakthrough process alternatives beyond conventional technology optimization

The worldwide use of chromium-based processes in tanneries generates increased concerns about their related environmental burdens. Cleaner production alternatives for leather production are being proposed, based on the optimization of specific aspects or criteria, for instance, reducing demand for specific materials and energy, or reducing local toxicological emissions. While improvement on individual characteristics of the process is certainly to be favored, a more comprehensive evaluation of alternatives is also needed to prevent the risk of shifting the burden to increase global load while addressing one specific critical factor of production. This work aims to discuss the importance of a multicriteria, multiscale approach to address cleaner production strategy costs and benefits. For this, materials balance, an economic approach, and emergy (with an “m”) accounting methods are applied to selected unhairing/liming, pickling/tanning and wastewater treatment steps in a tannery process, which was chosen as a case study. Results show that the assessed recycling cleaner production strategies assessed allow the manufacturer to reduce by one half the amount of water used and the demand for chemicals up to 4% with respect to the business-as-usual process, at the expense of increasing electricity demand by 10%. Economic cost-to-benefit ratio was 25$ benefits per 1$ invested, as well as an emergy-based cost-to-benefit of 33Em$ per 1Em$ invested, of course these improvements were limited to the three investigated process steps. The improvement in cost/benefit ratios indicates that converting scenario #0 into #1 is favorable under economic and emergy views. However, when the two scenarios are investigated from the point of view of the imbalance in local and renewable resource use versus imported and nonrenewable use, the emergy method shows a small overall increase in renewability (from 3.51% to 3.85%), a low, but expected, emergy yield ratio equal to 1, and a high environmental loading ratio (24.95 and 27.47). While the environmental cost–benefit ratio shows that recycling is a favorable option, the emergy performance indicators highlight that the efficiency of recycling is still insufficient and improvements in the tanning processes are needed to ensure renewability and sustainability. A number of process chemicals were involved in the investigated tannery operations, which required emergy evaluations. As a side result of this study, the Unit Emergy Values (UEVs) of SO{sub 2}, H{sub 2}SO{sub 4} Na{sub 2}SO{sub 4}, HCL, Na{sub 2}S, NaOH, CaO, Ca(OH){sub 2}, Cr{sub 2}O{sub 3}, MnSO{sub 4}, and Al(OH){sub 3}, were also calculated thus adding to the emergy database about chemicals. - Highlights: • Cleaner production strategies for tannery processes are presented and evaluated. • Local and global scales are considered under economical and biophysical approaches. • A multicriteria approach should be considered for decision making. • Recycling strategies have better indicators than traditional processes. • Emergy integrates energy and monetary indicators for more comprehensive assessment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Putting social impact assessment to the test as a method for implementing responsible tourism practice

The discourse on the social impacts of tourism needs to shift from the current descriptive critique of tourism to considering what can be done in actual practice to embed the management of tourism's social impacts into the existing planning, product development and operational processes of tourism businesses. A pragmatic approach for designing research methodologies, social management systems and initial actions, which is shaped by the real world operational constraints and existing systems used in the tourism industry, is needed. Our pilot study with a small Bulgarian travel company put social impact assessment (SIA) to the test to see if it could provide this desired approach and assist in implementing responsible tourism development practice, especially in small tourism businesses. Our findings showed that our adapted SIA method has value as a practical method for embedding a responsible tourism approach. While there were some challenges, SIA proved to be effective in assisting the staff of our test case tourism business to better understand their social impacts on their local communities and to identify actions to take. - Highlights: • Pragmatic approach is needed for the responsible management of social impacts of tourism. • Our adapted Social impact Assessment (SIA) method has value as a practical method. • SIA can be embedded into tourism businesses existing ‘ways of doing things’. • We identified challenges and ways to improve our method to better suit small tourism business context.

54 ENVIRONMENTAL SCIENCES↗