EPA has announced that it is proposing to revise the wastewater treatment exemptions for hazardous waste mixtures, an action also known as the "Headworks Rule Exemptions." Solvents formerly deemed hazardous are now declared treatable and exempt.
EPA is proposing the following four revisions: (1) the addition of two solvents (benzene and 2-ethoxyethanol) to a list of solvents whose mixtures are exempted from the rules under the Resource Conservation and Recovery Act (RCRA); (2) the addition of an option to directly measure solvent chemical levels at the headworks of the wastewater treatment system to the current requirement; (3) a clarification in the preamble that scrubber waters generated from the incineration of spent solvents listed in the headworks rule would be eligible for the exemption; (4) the addition of listed hazardous wastes as eligible for the de minimis exemption, as well as the addition of non-manufacturing facilities to those that qualify for this exemption if certain conditions are met.
Many of these proposed changes are reportedly based on feedback that EPA received during the public comment period. The headworks exemptions have been revised occasionally as new wastes have been added to the lists of hazardous wastes.
The reasoning behind each of these exemptions, according to EPA, is that the wastewater treatment system receives many different kinds of wastes, and the solvents, commercial chemical products, lab wastes, etc., are a "minuscule and treatable part of the mix of wastewaters."
The relatively small volumes of these organic constituents should be easily and effectively handled by the wastewater treatment system, so the risk to the environment would be negligible, EPA has stated.