Self-sustaining smouldering combustion for the treatment of industrial oily waste.

Significant onsite handling and offsite management costs are incurred by oilfield operators annually to properly manage hydrocarbon waste streams such as tank bottoms or other oily sludge or oil impacted soil generated during oil and gas production processes. The current study reports for the first-time technical results of a field trial on use of a smouldering combustion technology performed in an active oilfield. Two treatment batches with oily sludges, stabilized through blending with soil, resulted in permanent hydrocarbon removal (98-99.9% reduction) to create treated soil that met standards for reuse as clean backfill onsite. Emissions profile data collected pre- and post-thermal oxidizer indicated effective removal of volatile organic compounds, CO and SO2, but had increased NO and CO2 due to combustion of propane to affect the thermal oxidation. Regulatory, financial, environmental and safety considerations are discussed in context of future full-scale smouldering technology deployment. The technology has the potential to lower overall unit costs for management of hydrocarbon impacted waste and reduce waste sent to landfills, which can benefit more remote sites.

Priority screening of toxic chemicals and industry sectors in the U.S. toxics release inventory: a comparison of the life cycle impact-based and risk-based assessment tools developed by U.S. EPA.

Life Cycle Impact Assessment (LCIA) and Risk Assessment (RA) employ different approaches to evaluate toxic impact potential for their own general applications. LCIA is often used to evaluate toxicity potentials for corporate environmental management and RA is often used to evaluate a risk score for environmental policy in government. This study evaluates the cancer, non-cancer, and ecotoxicity potentials and risk scores of chemicals and industry sectors in the United States on the basis of the LCIA- and RA-based tools developed by U.S. EPA, and compares the priority screening of toxic chemicals and industry sectors identified with each method to examine whether the LCIA- and RA-based results lead to the same prioritization schemes. The Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI) is applied as an LCIA-based screening approach with a focus on air and water emissions, and the Risk-Screening Environmental Indicator (RSEI) is applied in equivalent fashion as an RA-based screening approach. The U.S. Toxic Release Inventory is used as the dataset for this analysis, because of its general applicability to a comprehensive list of chemical substances and industry sectors. Overall, the TRACI and RSEI results do not agree with each other in part due to the unavailability of characterization factors and toxic scores for select substances, but primarily because of their different evaluation approaches. Therefore, TRACI and RSEI should be used together both to support a more comprehensive and robust approach to screening of chemicals for environmental management and policy and to highlight substances that are found to be of concern from both perspectives.

Comparative alternative materials assessment to screen toxicity hazards in the life cycle of CIGS thin film photovoltaics.

Copper-indium-gallium-selenium-sulfide (CIGS) thin film photovoltaics are increasingly penetrating the market supply for consumer solar panels. Although CIGS is attractive for producing less greenhouse gas emissions than fossil-fuel based energy sources, CIGS manufacturing processes and solar cell devices use hazardous materials that should be carefully considered in evaluating and comparing net environmental benefits of energy products. Through this research, we present a case study on the toxicity hazards associated with alternative materials selection for CIGS manufacturing. We applied two numeric models, The Green Screen for Safer Chemicals and the Toxic Potential Indicator. To improve the sensitivity of the model outputs, we developed a novel, life cycle thinking based hazard assessment method that facilitates the projection of hazards throughout material life cycles. Our results show that the least hazardous CIGS solar cell device and manufacturing protocol consist of a titanium substrate, molybdenum metal back electrode, CuInS2 p-type absorber deposited by spray pyrolysis, ZnS buffer deposited by spray ion layer gas reduction, ZnO:Ga transparent conducting oxide (TCO) deposited by sputtering, and the encapsulant polydimethylsiloxane.

Integrating toxicity reduction strategies for materials and components into product design: a case study on utility meters.

Using RIO Tronics utility meter products as an industrial case study, the numeric Fraunhofer Toxic Potential Indicator (TPI) assessment tool is used to determine high impact materials with the aim of reducing the content of inherently toxic substances in these products. However, because product redesign with alternative materials affects entire components, overall component toxicity potential must also be explored. To achieve this, material TPI scores are aggregated into component TPI scores by 2 methods: 1) the Sum-Weighted Component TPI method, which considers the mass of materials in the component to assign an overall score, and 2) the Max Component TPI method, which scores the component with the highest impact material. With consideration of uncertainties from materials' toxicity information and mass estimates, key results from both scoring methods prioritized components that contain acrylonitrile-based polymers, polyvinyl chloride (PVC), and stainless steel. Furthermore, an alternative materials assessment is carried out to identify less-toxic substitutes to meet cost and technical constraints. Substitute materials such as Al alloys for stainless steel and high-density polyethylene for PVC show promise for a combination of toxicity reduction and cost-effectiveness. The new screening methodology described can help product designers systematically benchmark toxicity potential in parallel to cost and functionality.

International harmonization of models for selecting less toxic chemical alternatives: Effect of regulatory disparities in the United States and Europe.

The desire to reduce human exposure to toxic chemicals associated with consumer products that are marketed globally demands the creation of comparative toxicity assessment tools that are based on uniform thresholds of acceptable risks and guidelines for materials use across international boundaries. The Toxic Potential Indicator (TPI) is a quantitative model based on European Union (EU) regulatory standards for toxicity and environmental quality. Here, we describe a version of TPI that we developed with US regulatory thresholds for environmental and human health impacts of toxic materials. The customized US-based TPI (USTPI) model integrates occupational permissible exposure limits (PELs), carcinogen categories based on the scheme of the International Agency for Research on Cancer (IARC), and median effect concentration for acute aquatic toxicity (EC50s). As a case study, we compare calculated scores for EU-based TPI (EUTPI) and USTPI for a large group of chemicals including 578 substances listed in the US Toxics Release Inventory (TRI). Statistical analyses show that the median difference between USTPI and EUTPI scores do not approximate to zero, implying a general discrepancy in TPI score results. Comparison of chemical ranking with Spearman's correlation coefficient suggests a positive but imperfect rank correlation. Although some discrepancies between EUTPI and USTPI may be explained by missing toxicity information in some regulatory categories, disparities between the 2 models are associated mostly with different input parameters, i.e., different regulatory thresholds and guidelines. These results demonstrate that regional differences in regulatory thresholds for material toxicity may compromise the ideals of international agreements, such as the Globally Harmonized System (GHS) of Classification and Labeling of Chemicals, and emphasis needs to be placed on eliminating inconsistencies in hazard assessment frameworks for substances.

Environmental and risk screening for prioritizing pollution prevention opportunities in the U.S. printed wiring board manufacturing industry.

Modern manufacturing of printed wiring boards (PWBs) involves extensive use of various hazardous chemicals in different manufacturing steps such as board preparation, circuit design transfer, etching and plating processes. Two complementary environmental screening methods developed by the U.S. EPA, namely: (i) the Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) and (ii) Risk-Screening Environmental Indicators (RSEI), are used to quantify geographic and chemical environmental impacts in the U.S. PWB manufacturing industry based on Toxics Release Inventory (TRI) data. Although the release weight percentages of industrial chemicals such as methanol, glycol ethers and dimethylformamide comprise the larger fraction of reported air and water emissions, results indicate that lead, copper and their compounds' releases correspond to the highest environmental impact from toxicity potentials and risk-screening scores. Combining these results with further knowledge of PWB manufacturing, select alternative chemical processes and materials for pollution prevention are discussed. Examples of effective pollution prevention options in the PWB industry include spent etchant recovery technologies, and process and material substitutions. In addition, geographic assessment of environmental burden highlights states where promotion of pollution prevention strategies and emissions regulations can have the greatest effect to curb the PWB industry's toxic release impacts.

Quantity-based and toxicity-based evaluation of the U.S. Toxics Release Inventory.

The U.S. EPA Toxics Release Inventory (TRI) represents an extensive, publicly available dataset on toxics and, as such, has contributed to reducing the releases and disposal of toxic chemicals. The TRI, however, reports on a wide range of releases from different sources, some of which are less likely to generate a human or ecological hazard. Furthermore, the TRI is quantity based and does not take into account the relative toxicity of chemicals. In an effort to utilize the TRI more effectively to guide environmental management and policy, this work provides an in-depth analysis of the quantity-based TRI data for year 2007 at industry sector, state, and chemical levels and couples it with toxicity potentials. These toxicity potentials are derived from the U.S. EPA's TRACI (Tool for the Reduction and Assessment of Chemical and other environmental Impacts) characterization factors for cancer, non-cancer and ecotoxicity. The combination of quantity-based and toxicity-based analysis allows a more robust evaluation of toxics use and priorities. Results show, for instance, that none of the highest priority chemicals identified through the toxicity-based evaluation would have been identified if only quantity-based evaluation had been used. As the chemicals are aggregated to the state and industry sector levels, the discrepancies between the evaluation methods are less significant.