Environmental impact assessment of multi-source solid waste based on a life cycle assessment, principal component analysis, and random forest algorithm

As a national pilot city for solid waste disposal and resource reuse, Dongguan in Guangdong Province aims to vigorously promote the high-value utilization of solid waste and contribute to the sustainable development of the Greater Bay Area. In this study, life cycle assessment (LCA) coupled with principal component analysis (PCA) and the random forest (RF) algorithm was applied to assess the environmental impact of multi-source solid waste disposal technologies to guide the environmental protection direction. In order to improve the technical efficiency and reduce pollution emissions, some advanced technologies including carbothermal reduction‒oxygen-enriched side blowing, directional depolymerization‒flocculation demulsification, anaerobic digestion and incineration power generation, were applied for treating inorganic waste, organic waste, kitchen waste and household waste in the park. Based on the improved techniques, we proposed a cyclic model for multi-source solid waste disposal. Results of the combined LCA-PCA-RF calculation indicated that the key environmental load type was human toxicity potential (HTP), came from the technical units of carbothermal reduction and oxygen-enriched side blowing. Compared to the improved one, the cyclic model was proved to reduce material and energy inputs by 66%-85% and the pollution emissions by 15%-88%. To sum up, the environmental impact assessment and systematic comparison suggest a cyclic mode for multi-source solid waste treatments in the park, which could be promoted and contributed to the green and low-carbon development of the city.

Enhanced landfill process based on leachate recirculation and micro-aeration: A comprehensive technical, environmental, and economic assessment

The landfill is still the primary waste treatment method in developing countries. Due to the long stability time and long-term occupation of a large amount of land, the landfill poses a significant threat to the ecological environment and affects the process of urbanization. This study conducted a landfill simulation reactor (LSR) experiment to achieve rapid landfill stabilization through micro-aeration and leachate recirculation. More than 60 % of the degradable organic carbon in the enhanced process (LSR-IV contains 24 % of the retained carbon) can be relatively quickly converted to a gaseous state, which is nearly half higher than the degradation efficiency of the traditional process (LSR-I contains 59.3 % of the retained carbon). A comprehensive environmental assessment is developed for the enhanced process, and better environmental benefits are obtained from the whole landfill process. Compared with conventional treatment process, the enhanced process is applied to the actual landfill to analyze the economic cost. In terms of the total cost, the enhanced process cost (60.1 CNY) is about 44 % lower than the conventional landfill process cost (107.6 CNY). The enhanced process saves nearly half of the time cost and reduces the cost of land acquisition. This study can provide a reference for governmental and municipal administrations to carry out the technological transformation of traditional landfills from the aspects of technology, economy and environment.

Applying comprehensive environmental assessment to research planning for multiwalled carbon nanotubes: Refinements to inform future stakeholder engagement

Risk assessments and risk management efforts to protect human health and the environment can benefit from early, coordinated research planning by researchers, risk assessors, and risk managers. However, approaches for engaging these and other stakeholders in research planning have not received much attention in the environmental scientific literature. The Comprehensive Environmental Assessment (CEA) approach under development by the United States Environmental Protection Agency (USEPA) is a means to manage complex information and input from diverse stakeholder perspectives on research planning that will ultimately support environmental and human health decision making. The objectives of this article are to 1) describe the outcomes of applying lessons learned from previous CEA applications to planning research on engineered nanomaterial, multiwalled carbon nanotubes (MWCNTs) and 2) discuss new insights and refinements for future efforts to engage stakeholders in research planning for risk assessment and risk management of environmental issues. Although framed in terms of MWCNTs, this discussion is intended to enhance research planning to support assessments for other environmental issues as well. Key insights for research planning include the potential benefits of 1) ensuring that participants have research, risk assessment, and risk management expertise in addition to diverse disciplinary backgrounds; 2) including an early scoping step before rounds of formal ratings; 3) using a familiar numeric scale (e.g., US dollars) versus ordinal rating scales of "importance"; 4) applying virtual communication tools to supplement face-to-face interaction between participants; and 5) refining criteria to guide development of specific, actionable research questions.

Transparent stakeholder engagement in practice: Lessons learned from applying comprehensive environmental assessment to research planning for nanomaterials

As efforts to develop new applications of engineered nanoscale materials (ENMs) continue to grow, so too has interest in the environmental, health, and safety (EHS) implications of these materials. However, thorough evaluation and interpretation of such implications could require substantial resources (e.g., estimated as >$120 million per year in federal funding 2013-2017). A structured, strategic approach for transparently planning research would support improved linkages between ENM research and risk assessments, and thereby enhance the utility of financial and other resources for EHS studies of ENMs. For this reason, we applied Comprehensive Environmental Assessment (CEA) as an approach to provide transparent input into research planning for 2 types of ENMs: nanoscale titanium dioxide and nanoscale silver. For each of these CEA applications, we employed a collective judgment method known as Nominal Group Technique (NGT) in 2 workshops sponsored by the US Environmental Protection Agency (USEPA). The objective of this paper is to present the outcomes of these CEA applications in the context of how our methodology can inform future efforts to identify collective goals in science (e.g., research priorities) through structured decision support approaches. Outcomes include clear lists of research priorities for each ENM developed through transparently engaging stakeholders having diverse technical and sector perspectives. In addition, we identified several procedural aspects that could be refined, including emphasizing breakout group interactions, identifying broad information priorities before more detailed research questions, and using rating rather than ranking prioritization methods. Beyond the research directions identified for specific ENMs, lessons learned about engaging stakeholders in research planning are expected to inform future research planning efforts for ENMs and other emerging materials across the scientific community.

A web-based tool to engage stakeholders in informing research planning for future decisions on emerging materials

Prioritizing and assessing risks associated with chemicals, industrial materials, or emerging technologies is a complex problem that benefits from the involvement of multiple stakeholder groups. For example, in the case of engineered nanomaterials (ENMs), scientific uncertainties exist that hamper environmental, health, and safety (EHS) assessments. Therefore, alternative approaches to standard EHS assessment methods have gained increased attention. The objective of this paper is to describe the application of a web-based, interactive decision support tool developed by the U.S. Environmental Protection Agency (U.S. EPA) in a pilot study on ENMs. The piloted tool implements U.S. EPA's comprehensive environmental assessment (CEA) approach to prioritize research gaps. When pursued, such research priorities can result in data that subsequently improve the scientific robustness of risk assessments and inform future risk management decisions. Pilot results suggest that the tool was useful in facilitating multi-stakeholder prioritization of research gaps. Results also provide potential improvements for subsequent applications. The outcomes of future CEAWeb applications with larger stakeholder groups may inform the development of funding opportunities for emerging materials across the scientific community (e.g., National Science Foundation Science to Achieve Results [STAR] grants, National Institutes of Health Requests for Proposals).

What do the data show? Knowledge map development for comprehensive environmental assessment

Environmental and human health risk assessments benefit from using data that cross multiple scientific domains. Although individual data points may often be readily understood, the total picture can be difficult to envision. This is especially true with gaps in the data (e.g., with emerging substances such as engineered nanomaterials [ENM]), such that simply presenting only known information can result in a skewed picture. This study describes a method for building knowledge maps (KM) to visually summarize factors relevant to risk assessment in a relatively easy to interpret format. The KMs were created in the context of the comprehensive environmental assessment (CEA) approach for research planning and risk management of environmental contaminants. Recent applications of CEA to emerging substances such as engineered nanomaterials that have numerous data gaps have suggested that a more visually based depiction of information would improve the approach. We developed KM templates as a pilot project, to represent pertinent aspects of conceptual domains, and to highlight gaps in available information for one particular portion of a specific CEA application: the comparison of environmental transport, transformation, and fate of multiwalled carbon nanotubes (MWCNTs) and decabromodiphenyl ether as flame retardants. The results are 3 KM templates representing Physical Properties, Transport, and Transformation. The 3 templates were applied to both substances, resulting in a total of 6 KMs. In addition to presenting the KMs, this paper details the process used to generate them, to aid KM development for other sections of CEA applied to MWCNTs, or to apply the process to new CEA applications.