NIH Dark Room Operations

Wet photo-processing rooms (aka dark rooms) utilize special paper containing light-sensitive silver compounds to create a high-quality photograph. The solutions used during the development process release the unexposed silver compounds, creating a source of hazardous waste. As a result, it is crucial that all dark rooms on NIH campuses adhere to all Federal, State and local regulations for wastewater discharge. On the Bethesda campus, these regulations are enforced by the Environmental Protection Agency (EPA) and the Washington Suburban Sanitary Commission (WSSC). Dark rooms are subject to inspection by these groups, in addition to wastewater monitoring. Violations found from these compliance checks can result in fines and the suspension or revocation of discharge privileges.

In accordance with WSSC regulations pertaining to the silver limit in our effluent discharge, the NIH has determined that all dark rooms must have:


1) A silver recovery unit (SRU) or effluent precipitation and neutralization (EPAN) chamber.
2) Secondary containment placed under the SRU or EPAN chamber.
3) A maintenance record kept within the dark room area (a sticker with the most recent service date, at minimum).
4) A designated point of contact (POC), with their contact and IC information clearly posted outside the dark room.

Here is an example of a properly contained and labeled silver recovery unit:

A photograph of a silver recovery unit that is in compliance with WSSC and NIH policies.



























This silver recovery unit is properly labeled with a maintenance sticker and is placed inside secondary containment. To meet all of the requirements, contact information for the dark room's POC must be listed outside the room.

Any questions regarding the requirements for dark room operations should be directed to the Office of Research Facilities, Division of Environmental Protection at 301-496-7775.