Biological Disposal Of Hazardous Waste

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Biological disposal of hazardous waste
T. O. P E Y T O N
American Technology Management Consultants, P.O. B o x 1685, Lafayette, Indiana 4 7902, USA

Summary. Hazardous wastes pose major disposal problems for all industrialized nations and a need exists to develop effective and permanent solutions. Biological technologies can assist in this regard. Biosystems can serve to recover,separate and destroy the toxic nature o f hazardous waste at the source o f generation, at abandoned landfills, in surface and ground waters and at the site o f spills. When applying biotechnologies there are many physical, chemical and biological factors that must be considered when engineering an environment, with the biological component improved through the use o f applied microbiology and geneticengineering. Biotreatment process systems include conventional aerobic and anaerobic technologies, land treatments similar to farming operations and composting, and novel techniques to treat surface and ground waters. Emerging techniques include free and immobilized cells and enzymes in batch and continuous systems, high-rate fermentations, and coupling o f biotechnologies to physical/chemicalmethods. To develop an effective biological disposal option, research and development is required in a wide range o f areas associated with microbiology and genetic engineering, and system design and testing. Keywords." Pollution control; hazardous waste; genetic engineering;
enzyme engineering; biological disposal

exposed to xenobiotics in the environment. Thus, biotechnological applications usethese life forms, chiefly bacteria, in hazardous waste treatment.

The hazardous waste disposal p r o b l e m
One of the more serious environmental problems confronting industrialized nations today is the disposition of the large quantities of hazardous waste generated by many product manufacturers and users: These wastes pose various types and degrees of hazard, requiring carefully selectedmanagement techniques. In the United States, a number of federal legislations have been enacted to address the management of these materials, including three major environmental laws: the Resource Conservation and Recovery Act (RCRA); the Toxic Substances Control Act (TSCA); and the Comprehensive Environmental Response, Compensation and Liabilities Act (CERCLA). The scope of hazardous wasteregulation under these laws is listed in Table 1. The major hazardous waste legislation is embodied in Subtitle C of RCRA. Under RCRA, state legislations are required that must be no less stringent than the federal mandate. It is estimated that under the federal statute nearly 40 million metric ton of hazardous waste generated per year is regulated, whereas the more stringent state regulations control 250million metric tons. 1,2 Though much of the state total reflects an accounting of bulk waste of low hazard, such as coal ash and mining debris, this is offset when hazardous waste is inventoried from small generators and environmental media contaminated from spills and unauthorized dumping. Current disposal practices include landfilling, injection wells, incineration, stockpiling and surfaceimpoundments. Many of these
Table 1 Major US Federal legislations and regulations concerning hazardous waste control Legislation Resource Conservation and Recovery Act (RCRA) Subtitle C Regulation Identification and listing Manifest system for tracking waste Standards for treatment, storage and disposal Government response to spills o f hazardous materials into the environment Funds for compensationand authority to impose liability on clean-up cost Evaluation of risk of all chemicals in commerce and testing of new chemicals Controls manufacture, processing, distribution, use and disposal o f commercial substances posing unreasonable risks

Introduction
Many materials are classified as hazardous because they contain toxic chemicals that are mobile and persist in the environment,...