Treatment by generator
An acid or base may be neutralized and poured into the sanitary sewer only if the neutralized mixture is not toxic and final pH is greater than 5.5 and less than 12.
These acids and bases may not be neutralized and disposed of into a sanitary sewer:
- Perchloric acid at any concentration
- Nitric acid, concentrated
- Sulfuric acid, fuming (concentrated)
- Hydrofluoric acid (email firstname.lastname@example.org for information)
- Acids or bases with high concentrations of metals or other contaminants
- Acids or bases that contain dyes or surfactants
- Any organic acids and bases that are still toxic after neutralization (most organic acids and bases; one exception is acetic acid with a concentration of less than 80 percent)
CIDEX® OPA is used commonly in hospitals and some research laboratories to disinfect medical and some research devices.
OPA (orthophthaldehyde) is highly toxic to fish. Therefore, waste CIDEX® OPA needs to be treated before it can be poured down the drain. The OPA concentration in waste CIDEX® OPA is usually about 0.3-0.5 percent, however the King County sewer discharge limit is 0.01 percent.
Many commercial products are available to treat CIDEX® OPA. Follow product instructions for treatment time.
Ethidium bromide is a nucleic acid stain. It fluoresces under ultraviolet light, especially when bound to double-stranded DNA. It is also a strong mutagen and a possible carcinogen, so must be managed correctly.
Aqueous solutions of ethidium bromide with concentrations less than 10 µg/L (10 ppb) are not considered hazardous and may be discharged to the sewer. Solutions containing greater than 10 µg/L (10 ppb) must be chemically treated or collected as hazardous waste.
We recommend GreenBags for treating dilute (over 10 µg/L) solutions of ethidium bromide. The treated water can be disposed of in the sink. The tea bags, which contain activated carbon, absorb the ethidium bromide so tightly that it is safe to put them in the trash.
We give a starter kit of three tea bags to each laboratory. Call 206.616.5835 or email email@example.com to request them. You can buy more GreenBags from VWR via eProcurement. The product number is 100371-168, and a pack of 25 teabags costs about $90.
Gels that contain ethidium bromide may be doubled-bagged, labeled "non-hazardous" and placed in the trash if they contain less than 0.1 percent ethidium bromide. If the gel is pink or red, the ethidium concentration is higher than 0.1 percent. In this case, the gel is handled as hazardous waste.
Items contaminated with concentrated ethidium bromide are managed as hazardous waste. Pipette tips contaminated with dilute ethidium bromide are dried and placed into a lab glass bin. Other items contaminated with dilute ethidium bromide may be double-bagged, labeled "non-hazardous," and placed in the trash. Please double-bag to keep waste handlers from being exposed.
Formaldehyde, or formalin, is commonly used at concentrations near 3.7 percent in water to preserve specimens and samples. It also qualifies as hazardous waste when it is no longer needed. However, King County Wastewater Treatment Division allows us to discharge toxic formaldehyde to the sewer at concentrations of less than 0.1 percent. Therefore, formaldehyde must be treated to reduce its concentration before it is poured down the drain.
Treatment of formaldehyde in your laboratory is simple and easy. We currently recommend Neutralex or a similar product to destroy the formaldehyde. Use of Neutralex according to instructions will reduce formaldehyde concentrations to well below 0.1 percent.
Aqueous solutions containing mercuric chloride can be treated with mercury-selective chelate resins, which bind to and remove mercury ions from the solution. The water can then be discharged to the sewer and the resin collected as hazardous mercury waste. This program is in development; please contact us regarding treatment of mercuric chloride waste.