Health and environmental effects of coal-liquefaction processes: Environmentally acceptable technology development

Abstract

Chemically complex materials produced by several coal-liquefaction processes and under various stages of process design and operating conditions have been screened for potential health and environmental effects. Biologically active materials have been fractionated and rescreened. Chemical constituents of biologically active fractions have been identified, and the environmental fate of problematic agents is being determined. Coal-derived liquids are generally more active than shale oil and petroleum crudes in biological and ecological test systems. Biologically active agents include primary aromatic amines (PAA), polynuclear aromatic hydrocarbons (PAH), and phenols. Some components of coal-derived materials are taken up by biota and metabolized. Hydrotreating, a refining or upgrading process, reduces PAA, PAH and phenol content, as well as mutagenicity, carcinogenicity and toxicity of coal liquids. Selective distillation restricts PAA and PAH content, as well as mutagenicity and carcinogenicity, to high boiling range coal liquids. Other process conditions and environmental factors influence chemical characteristics and biological activity of resultant materials. Eliminating toxic input of coal liquids to ecological test systems results in partial system recovery. Recent findings indicate that biological responses to a particular chemial agent vary, depending on whether that material is presented to the organism or environment as a pure compound or in a complex mixture. Thus, results of studies with pure compounds cannot be used alone to predict effects of complex mixtures. The growing health and environmental data-base has been used in selecting process modifications and marketable products that minimize risk to man and the environment. The data have also been used in developing occupational health and industrial hygiene practices, and may aid selection of control technologies, mitigative strategies, special handling and accident prevention procedures and spill-cleanup options to enhance the environmental acceptability of a coal liquefaction industry.