Coal liquefaction process development: Solving potential health and environmental problems

Abstract

Chemists, biologists, ecologists, and engineers have been developing a data-base to identify and evaluate risks to humans and the environment and strategies to minimize potential risks from large-scale coal liquefaction. Coal-liquids produced by various processes and under various stages of design and operating conditions have been screened for potential health and environmental effects. Toxicologically active materials have been fractionated and chemical constituents of biologically active fractions have been identified, and the environmental fate of problematic agents is being determined. Results indicate that coal-derived liquids are generally more toxicologically active than shale oil and petroleum crudes. Bioactive agents include primary aromatic amines (PAA), polynuclear aromatic hydrocarbons (PAH), phenolics, and others. Some components of coal-derived materials are taken up by biota and metabolized. Hydrotreating reduces PAA, PAH, and phenol content, as well as toxicological response to coal-liquids. Selective distillation restricts PAA and PAH content, and mutagenicity and carcinogenicity to high-boiling-range materials. Other process conditions and environmental factors also influence chemical characteristics and toxicological activity of coal-derived liquids. Recent findings indicate that biological responses to a given coal-derived liquid component vary, depending on whether that material is presented to the organism or environment as a pure compound or in a complex mixture. The data-base described provides input for assessment and has been used by developers when selecting process modifications and product slates that minimize risk to humans and the environment. These data have also been used in developing occupational health and industrial hygiene practices and may aid in selection of control technologies, mitigative strategies, special handling and accident prevention procedures, or spill-clean-up options to enhance the environmental acceptability of a coal liquefaction industry.