General Information
Research and instruction in laboratories continually produce small amounts of aqueous wastes. In such cases, laboratory workers must decide whether to pour particular solutions down the drain or keep them for pick-up by REHS personnel. This guide will help them make such decisions.

Typically, unwanted chemicals are collected by REHS for disposal. This is done in accordance with Section A. "Policy for the Disposal of Chemicals." Certain materials are suitable for drain disposal. These should be carefully considered to ensure they do not cause damage to the plumbing system or cause other problems such as odors in a building.

The materials, which are suitable for drain disposal, are listed in the tables that follow. Other materials are prohibited from drain disposal without prior approval from REHS.

If you have questions about the suitability of other materials for drain disposal, or about the proper disposal of any laboratory material, please contact REHS at (732) 445-2550.

Drain disposal of dilute Acids and Alkalis

Acids and alkalis, which have been rendered neutral by the experimental process, may be discarded by drain disposal. Neutralization should be done in small quantities (i.e. no larger than 1 liter). This should be done as part of the experiment generating the waste.

It is inappropriate to collect a quantity of waste, from multiple experiments, and conduct batch neutralization process.

Proper care must be taken to adjust solutions to a pH of between 6 and 9. Generally, 1N hydrochloric acid can be used to neutralize alkaline materials and 1N sodium hydroxide can be used to neutralize acid materials.

When creating these 1N solutions, remember to SLOWLY add the acid to the water or the alkali to the water, not vice versa.

Drain disposal is properly done in the following manner:

1. Protective gear (gloves, laboratory apron, and safety goggles) must be worn.
2. Before pouring the solution, turn on the tap to get a good flow of water to wash it down. Make sure that the sink and drain lines are washed free of any substances that will generate noxious gases when mixed with the solutions. These substances include cyanides, sulfides, bisulfides, sulfites, bisulfites, nitrates, and nitrites.
3. Pour the solution down the drain slowly, making sure that before, during and after pouring, the tap is turned on to provide a strong flow of water that aids in washing it down the drain.

The following are drain disposable materials:

* For any chemical containing sodium, the corresponding potassium or ammonium (salt) compound may
be substituted.

References