See MPCA hazardous waste fact sheet #4.46, Managing Photographic and X-ray Waste [PDF 176KB].
Waste Reduction Tips
Switching to developer system cleaners that do not contain chromium or chromate may reduce hazardous waste disposal requirements. Some alternatives contain nitric acid or sodium hydroxide, making them corrosive. Ensure adequate personal protective equipment such as gloves when using these cleaners. Contact your vendor for non-chrome and less hazardous cleaners.