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Toxic Substances and Hazardous Wastes
Published in Frank R. Spellman, Kathern Welsh, Safe Work Practices for Wastewater Treatment Plants, 2018
Frank R. Spellman, Kathern Welsh
waste. Similarly, when asbestos is in place and undisturbed, it is a hazardous material; when it is broken, breached, or thrown away, it becomes a hazardous waste. The RCRA defines a substance as “hazardous” if it possesses any of the following four characteristics:Ignitability refers to the characteristic of being able to sustain combustion and includes the category of flammability (ability to start fires when heated to temperatures less than 140°F or less than 60°C).Corrosive substances (or wastes) may destroy containers, contaminate soils and groundwater, or react with other materials to cause toxic gas emissions. Corrosive materials pose a specific hazard to human tissue and aquatic life where the pH levels are extreme.Reactive substances may be unstable or have a tendency to react, explode, or generate pressure during handling. Pressure-sensitive or water-reactive materials fall into this category.Toxicity is a function of the effect of hazardous materials (or wastes) that may come into contact with water or air and be leached into the groundwater or dispersed in the environment.
Regulatory Definitions of Solid and Hazardous Waste
Published in Gary F. Lindgren, Managing Industrial Hazardous Waste, 2018
The characteristic of reactivity is described at 40 CFR 261.23. A reactive waste has a tendency to become chemically unstable under normal management conditions or react violently when exposed to air or mixed with water, or can generate toxic gases. Like the definition of solid ignitable wastes, the reactivity characteristic is a narrative definition without a mandatory testing protocol or specified decision levels. The intention is to identify the wastes that are extremely unstable, have the capability of liberating toxic gases, or have a tendency to react violently or explode. Again, generators of reactive wastes are assumed to know that their wastes possess this property and require special handling. This knowledge can be inferred by an examination of MSDS information on purchased components of the waste material, along with knowledge of the hazard characteristic of the waste in light of the materials or the process used.
Contaminated site remediation: Role and classification of technologies
Published in Katalin Gruiz, Tamás Meggyes, Éva Fenyvesi, Engineering Tools for Environmental Risk Management – 4, 2019
Analogously, the permeable reactive barrier can also be considered a flow-through solid-phase reactor or a filled column. The reactive process may be adsorption, absorption, oxidation, reduction, or any other chemical reaction or biological transformation, including biodegradation. The polluted groundwater flows continuously through the filled reactor, driven by the elevation difference, i.e. the natural groundwater flow. These natural flow circumstances can be influenced by manipulating the flow route and pressures (Meggyes et al., 2009). Hydrogeology of the surrounding soil is an important “technological parameter” in these cases as it (also) determines flow parameters.
Particulate suspension: a review of studies characterizing particulates and volatile organic compounds emissions during additive manufacturing processes
Published in Particulate Science and Technology, 2023
Sayed Kaes Maruf Hossain, Azul Toledo Vega, Delia Valles-Rosales, Young Ho Park, Sarada Kuravi, Hansuk Sohn
Many researchers have raised concerns about potential health risks associated with various additive manufacturing processes (Rejeski, Zhao, and Huang 2018). The emission of nanoparticles, UFPs, and VOCs during AM is confirmed by many studies (Mendes et al. 2017). While most scholars expressed their concerns relating different health risks to these emission characteristics, some reported that the concentration and rate of the emission of particulates are comparable to many day-to-day processes like cooking (Stephens et al. 2013; Azimi, Fazli, and Stephens 2017; Zhang et al. 2017). Despite these physical characteristics, particulates and VOCs could still be hazardous due to the possible toxic chemical composition containing carcinogens, reactive metals, and sensitizers (Stefaniak, Bowers, et al. 2019).