An assessment of time series methods in metal price forecasting

The international price for metals is pivotal in the profitability equation for mining companies. If producer prices rise, assuming production levels and costs remain the same, profits are expected to increase. Accordingly, producers welcome any means by which price instability and unpredictability can be reduced. The paper analyses the ability of two user-friendly time series forecasting techniques to predict future lead and zinc prices. The conclusion is that price forecasting is difficult. It should, however, be acknowledged that whilst neither of the two models are definitive, they are useful for the mining company vis-à-vis its planning process. In particular, the results from the analysis in this paper suggest that ARIMA modelling provides marginally better forecast results than lagged forward price modelling. The methodologies employed in this paper have a broad based application to base metal forecasting by mining companies in general, that is, the applications are transferable.     

Air quality assessment for land disposal of industrial wastes

Air pollution from hazardous waste landfills and lagoons is largely unknown. Routine monitoring of toxic air contaminants associated with hazardous waste facilities is difficult and very costly. The method presented in this paper would be useful for air quality assessment in the absence of monitoring data. It may be used as a screening process to examine the question of whether or not volatilization is considered to be significant for a given contaminant and also to evaluate permit applications for new hazardous waste facilities concerning waste volatilization problems.     

Techno-economic analysis and environmental impact assessment of energy recovery from Municipal Solid Waste (MSW) in Brazil

Due to the lack of appropriate policies in the last decades, 60% of Brazilian cities still dump their waste in non-regulated landfills (the remaining ones dump their trash in regulated landfills), which represent a serious environmental and social problem. The key objective of this study is to compare, from a techno-economic and environmental point of view, different alternatives to the energy recovery from the Municipal Solid Waste (MSW) generated in Brazilian cities. The environmental analysis was carried out using current data collected in Betim, a 450,000 inhabitants city that currently produces 200 tonnes of MSW/day. Four scenarios were designed, whose environmental behaviour were studied applying the Life Cycle Assessment (LCA) methodology, in accordance with the ISO 14040 and ISO 14044 standards. The results show the landfill systems as the worst waste management option and that a significant environmental savings is achieved when a wasted energy recovery is done. The best option, which presented the best performance based on considered indicators, is the direct combustion of waste as fuel for electricity generation. The study also includes a techno-economical evaluation of the options, using a developed computer simulation tool. The economic indicators of an MSW energy recovery project were calculated. The selected methodology allows to calculate the energy content of the MSW and the CH₄ generated by the landfill, the costs and incomes associated with the energy recovery, the sales of electricity and carbon credits from the Clean Development Mechanism (CDM). The studies were based on urban centres of 100,000, 500,000 and 1,000,000 inhabitants, using the MSW characteristics of the metropolitan region of Belo Horizonte. Two alternatives to recovering waste energy were analyzed: a landfill that used landfill biogas to generate electricity through generator modules and a Waste-to-Energy (WtE) facility also with electricity generation. The results show that power generation projects using landfill biogas in Brazil strongly depend on the existence of a market for emissions reduction credits. The WtE plant projects, due to its high installation, Operation and Maintenance (O&M) costs, are highly dependent on MSW treatment fees. And they still rely on an increase of three times the city taxes to become attractive.     

An ecological approach to environmental impact assessment

Carbon cycling analysis is presented as a means for assessing anthropogenic perturbations in an ecosystem. Data from oligotrophic, eutrophic, and dystrophic (bog) lakes are used to show general trends in the lacustrine carbon cycle. The oligotrophic lake is an unstressed system and the eutrophic lake is under nutrient enrichment with high algal standing crops and productivity. The bog lake is a pH-stressed environment that is primarily a grazing ecosystem. It is hoped that a more effective environmental impact assessment will result from the use of carbon cycling as a unifying concept in ecosystem analysis.     

Environmental and economic impact assessment of construction and demolition waste disposal using system dynamics

Construction and demolition wastes (CDW) have increasingly serious problems in environmental, social, and economic realms. There is no coherent framework for utilization of these wastes which are disposed both legally and illegally. This harms the environment, contributes to the increase of energy consumption, and depletes finite landfills resources. The aim of this paper is to evaluate the impacts of two alternatives for the management of CDW, recycling and disposing. The evaluation is carried out through developing a dynamic model with aid STELLA software by conducting the following steps: (1) quantifying the total cost incurred to mitigate the impacts of CDW landfills and uncollected waste on the environment and human health; (2) quantifying the total avoided emissions and saved energy by recycling waste; (3) estimating total external cost saved by recycling waste and; (4) providing a decision support tool that helps in re-thinking about waste disposal. The proposed evaluation methodology allows activating the stringent regulations that restrict waste disposal and developing incentives to encourage constructors to recycle their wastes. The research findings show that recycling CDW leads to significant reductions in emissions, energy use, global warming potential (GWP), and conserves landfills space when compared to disposal of wastes in landfills. Furthermore, the cost of mitigating the impact of disposal is extremely high. Therefore, it is necessary to recycle construction and demolition wastes.     

An approach to tackling the environmental and health impacts of municipal solid waste disposal in developing countries

Indiscriminate disposal of municipal solid waste in developing countries poses severe environmental and health threats. The study proposes a new method for dealing with these problems. The hybrid structural interaction matrix (HSIM) was used to prioritise major identifiable environmental health factors arising from improper solid waste disposal. The simplistic resource allocation model was adopted to ensure optimality in the allocation of resources to prioritised factors. The study indicates that tackling environmental health impacts from the most prioritised negative disposal factors through optimal allocation of resources, will either reduce or eliminate the impacts associated with subsequent less prioritised factors that are direct consequences of the highly prioritised negative factors. The method proposed will aid decision makers in knowing which set of systemic factors are to be given preference and to what extent at given periods in time.     

Life cycle assessment for reuse/recycling of donated waste textiles compared to use of virgin material: An UK energy saving perspective

In the UK, between 4 and 5% of the municipal solid waste stream is composed of clothes/textiles. Approximately 25% of this is recycled by companies such as the Salvation Army Trading Company Limited (SATCOL) who provide a collection and distribution infrastructure for ‘donated’ clothing and shoes. Textiles can be reused or undergo a processing stage and enter a recycling stream. Research was conducted in order to quantify the energy used by a reuse/recycling operation and whether this resulted in a net energy benefit. The energy footprint was quantified using a streamlined life cycle assessment (LCA), an LCA restricted in scope in order to target specific aspects of the footprint, in this case energy consumption. Taking into account extraction of resources, manufacture of materials, electricity generation, clothing collection, processing and distribution and final disposal of wastes it was demonstrated that for every kilogram of virgin cotton displaced by second hand clothing approximately 65 kWh is saved, and for every kilogram of polyester around 90 kWh is saved. Therefore, the reuse and recycling of the donated clothing results in a reduction in the environmental burden compared to purchasing new clothing made from virgin materials.     

Study on assessment of slope stability and mixed disposal of overburden in voids of Singrauli Coalfield

The mining industry can be considered the backbone of the Indian economy as well as facilitating the power that drives most of the other industries in the company. The overburden and waste rocks produced during coal mining are major concerns in regard to the amount of land that is required for their disposal, as well as the stability of dumps for these materials, which are of increasing height. Land reclamation issues are also a concern. In this work the adverse impacts caused by the dumping of overburden on land and acidic mine water on water bodies is discussed. Remote sensing tools were used along with the laboratory experimentation to assess the various impacts. This study also shows that silt released from waste dumps, can affected the angle of repose of the overburden dump slope. The angle of repose of the overburden materials varies with particle size composition. Thus, use of in‐pit crushers in large opencast mining operations can effectively reduce the area locked under the waste dumps. The acid neutralization potential of fly ash and overburden for the treatment of acid water was tested in the laboratory by using fly ash and waste rock materials on acidic coalfield water. The results are encouraging, and fly ash may prove to be a good acid neutralizer when used in conjunction of coal overburden material.     

A comparison of disposal methods for on-site sewage facilities within the state of Texas,USA

Currently, 1.5 million homes in Texas, USA utilize an on-site sewage facility to manage their household waste. This study compares the conventional septic dispersal technology of perforated pipe drain field with two of the new technologies recently implemented in Texas, multi-pipe and chamber systems, determining if soil classification and climate are influencing factors in functional ability for each of the technologies. There is no statistical significance for failure of a system with respect to system type or climate zone. The textural classification of soil is a statistically significant variable in septic system failures. Soil type III, which includes the clay groups except pure clays and silty clay, appears to significantly influence system failures. Additionally, occupant misuse and lack of maintenance are contributing factors to system failure.     

The impact of domestic energy efficiency retrofit schemes on householder attitudes and behaviours

Retrofitting existing housing stock to improve energy efficiency is often required to meet climate mitigation, public health and fuel poverty targets. Increasing uptake and effectiveness of retrofit schemes requires understanding of their impacts on householder attitudes and behaviours. This paper reports results of a survey of 500 Kirklees householders in the UK, where the Kirklees Warm Zone scheme took place. This was a local government led city scale domestic retrofit programme that installed energy efficiency measures at no charge in over 50,000 houses. The results highlight key design features of the scheme, socio-economic and attitudinal factors that affected take-up of energy efficiency measures and impacts on behaviour and energy use after adoption. The results emphasise the role that positive feedback plays in reinforcing pro-environmental attitudes and behaviours of participants and in addressing concerns of non-participants. Our findings have implications for the design and operation of future domestic energy efficiency retrofit schemes.     

An approach to integrate impact scoping with environmental impact assessment

Impact scoping is the process of identifying important issues of a proposal and focusing the environmental impact assessment (EIA) on the high-priority issues. Although impact scoping in one form or another has been inherent to EIA for some time, documentation of its development and discussion of refinements to impact scoping processes have not been forthcoming. This article traces the development of impact scoping through time and highlights the need for such processes in EIA. A focused environmental assessment (FEA) approach to impact scoping that is suitable for implementation in an EIA is presented here and advantages of its use are delineated. FEA is a three-staged process that encourages impact scoping through progressive steps including impact identification, assessment and management planning. FEA combines a suite of EIA methods including: issues matrices, impact hypotheses, valued ecosystem components, and stakeholder participation sessions to effectively integrate impact scoping with EIA.     

Performance assessment of integrated energy systems for HVAC applications

In this article, energy and exergy analyses are conducted for two integrated systems which can be used in HVAC applications. These two systems are analyzed for the cases of single generation, cogeneration and trigeneration, and their performances are evaluated through energy and exergy efficiencies. The parametric studies are performed to investigate the effects of using cogeneration and extended to trigeneration on the system performance. To perform the comparisons between the systems for multiple options, the same amounts of outputs (in terms of electricity, heating, cooling) are produced for all systems. The energy analyses of systems 1 and 2 show a great benefit for moving from single generation to trigeneration, with the trigeneration efficiencies of 83.5% and 87.2%, respectively, and single generation efficiencies of 47% for both systems. However, the exergy analyses show that trigeneration may not always become more efficient than single generation, particularly for system 1, due to the fact that the trigeneration exergy efficiency is 38.7% and the corresponding single generation efficiency is 44.3%. For system 2, the trigeneration exergy efficiency is 52.7% while the single generation efficiency becomes 44.3%. Depending on the type of cogeneration or cogeneration design, the system can be more efficient.     

Field olfactometry assessment of dairy manure land application methods

Surface application of manure in reduced tillage systems generates nuisance odors, but their management is hindered by a lack of standardized field quantification methods. An investigation was undertaken to evaluate odor emissions associated with various technologies that incorporate manure with minimal soil disturbance. Dairy manure slurry was applied by five methods in a 3.5-m swath to grassland in 61-m-inside-diameter rings. Nasal Ranger Field Olfactometer (NRO) instruments were used to collect dilutions-to-threshold (D/T) observations from the center of each ring using a panel of four odor assessors taking four readings each over a 10-min period. The Best Estimate Threshold D/T (BET10) was calculated for each application method and an untreated control based on preapplication and <1 h, 2 to 4 h, and approximately 24 h after spreading. Whole-air samples were simultaneously collected for laboratory dynamic olfactometer evaluation using the triangular forced-choice (TFC) method. The BET10 of NRO data composited for all measurement times showed D/T decreased in the following order (a = 0.05): surface broadcast > aeration infiltration > surface + chisel incorporation > direct ground injection Sshallow disk injection > control, which closely followed laboratory TFC odor panel results (r = 0.83). At 24 h, odor reduction benefits relative to broadcasting persisted for all methods except aeration infiltration, and odors associated with direct ground injection were not different from the untreated control. Shallow disk injection provided substantial odor reduction with familiar toolbar equipment that is well adapted to regional soil conditions and conservation tillage operations.     

An assessment of Scottish development planning

The present development plan system in Scotland began in 1975. Its origins and purpose are discussed. Progress in the submission and adoption/approval of local and structure plans and in reviewing these plans is outlined. Performance to date is assessed and means of improvement are suggested, in relation to timeliness, transparency, scope and quality.     

Transitions of municipal solid waste management. Part II: Hybrid life cycle assessment of Swiss glass-packaging disposal

In policy support of municipal solid waste (MSW) management, life cycle assessment (LCA) can serve to compare the environmental or economic impacts of two or more options for waste processing. The scope of waste management LCAs generally focuses less attention on future developments, e.g., where will recycling take place, and more on the environmental performance of prototypes, e.g., the incineration of all waste compared to recycling. To provide more robust support for Swiss waste glass-packaging disposal, scenarios of Swiss waste glass-packaging are assessed from a life cycle perspective. The scenarios consist in schemes for the disposal of the total amount of Swiss waste glass-packaging, i.e., different combinations of recycling and downcycling in Switzerland or abroad developed in Part I, Meylan et al. (2013). In this article (Part II), the disposal schemes are assessed with respect to eco-efficiency, an indicator that combines total environmental impacts and gross value added in Switzerland. Results show that no policy alternative guarantees environmental impact reductions and gross value added gains under all developments of exogenous constraints. Downcycling to foam glass in Switzerland is not only an environmentally sound disposal option, but it also buffers gross value added losses in case domestic recycling (and thus glass-packaging production in Switzerland) ceases in the future. The substitution of products based on raw materials other than Swiss cullet is the main responsible for change in environmental and economic impacts. Hence, an eco-efficiency maximizing policy should consider the products of disposal schemes. The combination of scenario analysis and eco-efficiency assessment as presented in this paper can be applied to other contexts (i.e., countries, waste fractions).     

Preliminary estimations of energy and cost for CO2 recovery by a membrane flash process utilizing waste thermal energy

The membrane flash process utilizing waste thermal energy was developed to achieve an energy-saving technology and to substitute it for a conventional regenerator. The operating conditions of the membrane flash at high temperature were studied. The petroleum refining process and iron manufacturing process were proposed for candidate processes that actually had waste energy sources. The DEA concentration and the flashing pressure had optimum values to improve the performance and reduce the energy consumption for CO₂ recovery. Energy consumptions and costs for CO₂ recovery in the membrane flash and chemical absorption were estimated by a process simulator and discussed under the same conditions. The membrane flash can achieve lower energy capture than the chemical absorption for the above industrial processes. The membrane flash is suitable for the CO₂ emission sources that had high CO₂ concentration independently of the plant scale. The chemical absorption can be applied if the plant scale is large and also the CO₂ concentration is low.     

Use of strategic environmental assessment in the site selection process for a radioactive waste disposal facility in Slovenia

The benefits of strategic environmental considerations in the process of siting a repository for low- and intermediate-level radioactive waste (LILW) are presented. The benefits have been explored by analyzing differences between the two site selection processes. One is a so-called official site selection process, which is implemented by the Agency for radwaste management (ARAO); the other is an optimization process suggested by experts working in the area of environmental impact assessment (EIA) and land-use (spatial) planning. The criteria on which the comparison of the results of the two site selection processes has been based are spatial organization, environmental impact, safety in terms of potential exposure of the population to radioactivity released from the repository, and feasibility of the repository from the technical, financial/economic and social point of view (the latter relates to consent by the local community for siting the repository). The site selection processes have been compared with the support of the decision expert system named DEX. The results of the comparison indicate that the sites selected by ARAO meet fewer suitability criteria than those identified by applying strategic environmental considerations in the framework of the optimization process. This result stands when taking into account spatial, environmental, safety and technical feasibility points of view. Acceptability of a site by a local community could not have been tested, since the formal site selection process has not yet been concluded; this remains as an uncertain and open point of the comparison.     

Municipal solid waste management in South Africa: from waste to energy recovery through waste-to-energy technologies in Johannesburg

ABSTRACT

“Waste-to-energy” (WTE) technologies have been presented as one of the avenues to improve the management of solid waste whilst promoting clean and healthy urban environments through the recovery of waste and generation of energy. Research suggests that with the right investment in technologies and institutional changes, waste can potentially become a resource that can contribute to the socio-economic development of cities. It is in this context that this paper presents a review of the literature on WTE technologies and their implications on sustainable waste management in urban areas. The paper particularly contributes to our understanding of WTE technologies and its potential on Municipal Solid Waste Management (MSWM) in Johannesburg, South Africa. It is estimated that the city of Johannesburg’s landfills airspace will be completely depleted by year 2023. This projection becomes a motivation for the identification of suitable WTE alternative avenues to manage waste in the city. The paper argues that WTE technologies can contribute significantly to sustainable waste management, economic growth, ecological and environmental well-being.     

Evaluation of unmitigated options for municipal waste disposal site in Tehran,Iran using an integrated assessment approach

It can be difficult for assessors and decision-makers to compare different options for a project, and thus come to a reasoned and objective decision concerning the impacts and its sustainability at the local level. Therefore, using integrated assessment becomes crucially important for evaluating proposed different options. In this paper, we apply the Rapid Integrated Sustainability Assessment Method (RISAM) to evaluate the proposed unmitigated options for a municipal waste disposal site in Tehran, Iran. The results obtained showed that all of the alternative unmitigated options to the current method of open dumping were indicated as being consistent with very weak sustainability. The RISAM method demonstrated offers potential considerable benefits with respect to improved efficiency, reduced need for resources, and improved consistency and transparency in evaluation and reporting.     

A preliminary process design and economic assessment of a catalyst rejuvenation process for waste disposal of refinery spent catalysts

Spent hydroprocessing catalysts from refineries have been classified as hazardous solid waste by the United States Environmental Protection Agency (USEPA), refiners must find a viable but economical solution to solve this serious environmental issue. Catalyst rejuvenation is an attractive option for minimizing the environmental problems associated with spent catalysts. In this study, a preliminary design for such a process and the corresponding economic analysis are performed to assess the proposed catalyst rejuvenation process for metal-fouled spent catalysts generated in residue hydroprocessing units. The scenarios used in the economic assessment are based on three options of process synthesis and two operator modes. It is found that the option of rejuvenating medium and lightly fouled spent catalyst produced by the refinery will be the best solution for refiners, both environmentally and economically.