Used developer solutions are typically considered non-hazardous waste because their silver content is usually below the regulatory level of 5 mg/L.18 In most jurisdictions, the solution may be disposed of in the municipal sewer system if the pH is within 6 to 10. The State-by-State Hazardous Waste Resource Locator provides information for specific jurisdictions.4 Used developer solution should never be disposed of in a septic system, it will destabilize the system.
Some x-ray processing systems mix the spent developer and fixer and render the solution hazardous waste. Consider changing the equipment. It is also of note that unused developer solutions typically contain 1 to 5 percent hydroquinone. While this chemical is not considered hazardous waste by the EPA, it is neither listed nor characteristic, many state and local jurisdictions restrict its disposal. Consult the State-by-State Hazardous Waste Resource Locator.4