Mathematical Analysis of a Novel Approach to Maximize Waste Recovery in a Life Support System

NASA has been evaluating closed-loop atmosphere revitalization architectures carbon dioxide, CO2, reduction technologies. The CO2 and steam, H2O, co-electrolysis process is another option that NASA has investigated. Utilizing recent advances in the fuel cell technology sector, the Idaho National Laboratory, INL, has developed a CO2 and H2O co-electrolysis process to produce oxygen and syngas (carbon monoxide, CO and hydrogen, H2 mixture) for terrestrial (energy production) application. The technology is a combined process that involves steam electrolysis, CO2 electrolysis, and the reverse water gas shift (RWGS) reaction. Two process models were developed to evaluate novel approaches for waster recovery in a life support system. The first is a model INL co-electrolysis process combined with a methanol production process. The second is the INL co-electrolysis process combined with a pressure swing adsorption (PSA) process. For both processes, the overall power increases as the syngas ratio, H2/CO, increases because more water is needed to produce more hydrogen at a set CO2 incoming flow rate. The power for the methanol cases is less than the PSA because heat is available from the methanol reactor to preheat the water and carbon dioxide entering the co-electrolysis process

Municipal wastewater treatment with pond technology : historical review and future outlook

Facing an unprecedented population growth, it is difficult to overstress the assets for wastewater treatment of waste stabilization ponds (WSPs), i.e. high removal efficiency, simplicity, and low cost, which have been recognized by numerous scientists and operators. However, stricter discharge standards, changes in wastewater compounds, high emissions of greenhouse gases, and elevated land prices have led to their replacements in many places. This review aims at delivering a comprehensive overview of the historical development and current state of WSPs, and providing further insights to deal with their limitations in the future. The 21st century is witnessing changes in the way of approaching conventional problems in pond technology, in which WSPs should no longer be considered as a low treatment technology. Advanced models and technologies have been integrated for better design, control, and management. The roles of algae, which have been crucial as solar-powered aeration, will continue being a key solution. Yet, the separation of suspended algae to avoid deterioration of the effluent remains a major challenge in WSPs while in the case of high algal rate pond, further research is needed to maximize algal growth yield, select proper strains, and optimize harvesting methods to put algal biomass production in practice. Significant gaps need to be filled in understanding mechanisms of greenhouse gas emission, climate change mitigation, pond ecosystem services, and the fate and toxicity of emerging contaminants. From these insights, adaptation strategies are developed to deal with new opportunities and future challenges

ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis Project

Fiscal year 1987 research activities and accomplishments for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division are presented. The project's technical activities were organized into three work elements. The Molecular Modeling and Applied Genetics work element includes modeling and simulation studies to verify a dynamic model of the enzyme carboxypeptidase; plasmid stabilization by chromosomal integration; growth and stability characteristics of plasmid-containing cells; and determination of optional production parameters for hyper-production of polyphenol oxidase. The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields, and lower separation energetics. The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the economics and energetics of a given biocatalyst process

Environmentally Extended Input–Output Analysis of the UK Economy: Key Sector Analysis

The paper assesses the sustainability of investment in various economic sectors, with the aim of minimizing resource use and generation of emissions. The broad development focus of the paper and the potential for the proposed methodology to be applied in many different countries make it a useful methodological contribution to the global sustainability debate. The UK case is taken for illustration purposes, and (given the availability of the necessary data) this methodology could be applied in countries with various economic structures and specialisations. An environmentally extended static 123-sector UK input–output model is used, linking a range of physical flows (domestic extraction, use of water, and emissions of CO2, CH4, NOx) with the economic structure of the UK. A range of environmentally adjusted forward and backward linkage coefficients has been developed, adjusted according to final demand, domestic extraction, publicly supplied and directly abstracted water, amd emissions of CO2 and NOx,. The data on the final demandadjusted and environmentally adjusted forward and backward linkage coefficients were used in a multi-criteria decision-aid assessment, employing a NAIADE method in three different sustainability settings. The assessment was constructed in such a way that each sector of the UK economy was assessed by means of a panel of sustainability criteria, maximizing economic effects and minimizing environmental effects. This type of multi-criteria analysis, applied here for the first time, could prove to be a valuable basis for similar studies, especially in the developing world, where trade-offs between economic development and environmental protection have been the subject of considerable debate.input–output analysis; environmentally extended; MCDA; key sectors; sustainability; ecological economics; UK

Cooperation in manure-based biogas production networks: An agent-based modeling approach

Biogas production from manure has been proposed as a partial solution to energy and environmental concerns. However, manure markets face distortions caused by considerable unbalance between supply and demand and environmental regulations imposed for soil and water protection. Such market distortions influence the cooperation between animal farmers, biogas producers and arable land owners causing fluctuations in manure prices paid (or incurred) by animal farmers. This paper adopts an agent-based modeling approach to investigate the interactions between manure suppliers, i.e., animal farmers, and biogas producers in an industrial symbiosis case example consisting of 19 municipalities in the Overijssel region (eastern Netherlands). To find the manure price for successful cooperation schemes, we measure the impact of manure discharge cost, dimension and dispersion of animal farms, incentives provided by the government for bioenergy production, and the investment costs of biogas plants for different scales on the economic returns for both actor types and favorable market conditions. Findings show that manure exchange prices may vary between −3.33 €/t manure (i.e., animal farmer pays to biogas producer) and 7.03 €/t manure (i.e., biogas producer pays to animal farmer) and thanks to cooperation, actors can create a total economic value added between 3.73 €/t manure and 39.37 €/t manure. Hence, there are cases in which animal farmers can profitably be paid, but the presence of a supply surplus not met by demand provides an advantage to arable land owners and biogas producers in the price contracting phase in the current situation in the Netherlands

Environmentally Extended Input-Output Analysis of the UK Economy: Key Sector Analysis

The paper assesses the sustainability of investment in various economic sectors, with the aim of minimizing resource use and generation of emissions. The broad development focus of the paper and the potential for the proposed methodology to be applied in many different countries make it a useful methodological contribution to the global sustainability debate. The UK case is taken for illustration purposes, and (given the availability of the necessary data) this methodology could be applied in countries with various economic structures and specialisations. An environmentally extended static 123-sector UK input-output model is used, linking a range of physical flows (domestic extraction, use of water, and emissions of CO2, CH4, NOx) with the economic structure of the UK. A range of environmentally adjusted forward and backward linkage coefficients has been developed, adjusted according to final demand, domestic extraction, publicly supplied and directly abstracted water, amd emissions of CO2 and NOx,. The data on the final demand-adjusted and environmentally adjusted forward and backward linkage coefficients were used in a multi-criteria decision-aid assessment, employing a NAIADE method in three different sustainability settings. The assessment was constructed in such a way that each sector of the UK economy was assessed by means of a panel of sustainability criteria, maximizing economic effects and minimizing environmental effects. This type of multi-criteria analysis, applied here for the first time, could prove to be a valuable basis for similar studies, especially in the developing world, where trade-offs between economic development and environmental protection have been the subject of considerable debate.

Treatment and valorization plants in materials recovery supply chain

Aim of industrial symbiosis is to create synergies between industries in order to exchange resources (by-products, water and energy) through geographic proximity and collaboration [1]. By optimizing resource flows in a “whole-system approach”, a minimization of dangerous emissions and of supply needs can be achieved. Resources exchanges are established to facilitate recycling and re-use of industrial waste using a commercial vehicle. Several paths can be identified in order to establish an industrial symbiosis network (Figure 1, left), in relation (i) to the life cycle phase (raw material, component, product) and (ii) to the nature (material, water, energy) of the resource flows to be exchanged. Sometimes by-products and/or waste of an industrial process have to be treated and valorized in order to become the raw materials for others. In particular, two main treatment processes can be identified: refurbishment/upgrade for re-use (Figure 1, center) and recycling for material recovery (Figure 1, right). A brief overview of technological and economic aspects is given, together with their relevance to industrial symbiosis

Economic and environmental strategies for process design

This paper first addresses the definition of various objectives involved in eco-efficient processes, taking simultaneously into account ecological and economic considerations. The environmental aspect at the preliminary design phase of chemical processes is quantified by using a set of metrics or indicators following the guidelines of sustainability concepts proposed by . The resulting multiobjective problem is solved by a genetic algorithm following an improved variant of the so-called NSGA II algorithm. A key point for evaluating environmental burdens is the use of the package ARIANE™, a decision support tool dedicated to the management of plants utilities (steam, electricity, hot water, etc.) and pollutants (CO2, SO2, NO, etc.), implemented here both to compute the primary energy requirements of the process and to quantify its pollutant emissions. The well-known benchmark process for hydrodealkylation (HDA) of toluene to produce benzene, revisited here in a multiobjective optimization way, is used to illustrate the approach for finding eco-friendly and cost-effective designs. Preliminary biobjective studies are carried out for eliminating redundant environmental objectives. The trade-off between economic and environmental objectives is illustrated through Pareto curves. In order to aid decision making among the various alternatives that can be generated after this step, a synthetic evaluation method, based on the so-called Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) (), has been first used. Another simple procedure named FUCA has also been implemented and shown its efficiency vs. TOPSIS. Two scenarios are studied; in the former, the goal is to find the best trade-off between economic and ecological aspects while the latter case aims at defining the best compromise between economic and more strict environmental impact

Mineral Resources: Stocks, Flows, and Prospects

This chapter focuses on metals as they provide the clearest example of the challenges and opportunities that mineral resources present to society, in terms of both primary production and recycling. Basic concepts, information requirements and sources of consumer and industrial resource demand are described as well as the destabilizing effects of volatile resource prices and supply chain disruptions. Challenges facing extraction of in-ground resources and production of secondary resources are discussed and scenarios for the future considered. The results of the scenarios indicate that particularly energy and, as well, water and land requirements could become increasingly constraining factors for metal production. Key research questions are posed and modeling and data priorities discussed, with an emphasis on areas that require novel concepts and analytic tools to help lessen negative environmental impacts associated with minerals. The challenge of sustainability requires collaboration of practitioners and analysts with a multidisciplinary understanding of a broad set of issues, including economics, engineering, geology, ecology, and mathematical modeling, to name a few, as well as policy formulation and implementation.

Service-oriented disassembly sequence planning for electrical and electronic equipment waste

Disassembly sequence planning plays an important role in the end-of-life treatment of electrical and electronic equipment waste (e-waste). Effective planning methods can improve recovery rates and reduce environmental impacts of e-waste. In previous work, neither mathematical models nor optimization algorithms offered a satisfactory solution for this multi-objective disassembly problem. We present a multi-objective model for the problem and a modified teaching-learning-based optimization (MTLBO) algorithm to find the Pareto-optimal frontier. We use numerical simulations to demonstrate and verify the effectiveness and robustness of the algorithm. To do effective disassembly planning, all the participants in the lifecycle of e-waste should work together. Disassembly and recovery of e-waste involve complex processes across the lifecycle. Information support services, disassembly modeling and optimization services must be integrated using computer networks. We also propose a service-oriented framework to support business integration for the participants in the e-waste lifecycle. Effective and optimized disassembly planning can be achieved by invoking the related distributed services. The proposed framework is a novel e-business application for the end-of-life treatment of e-waste