Wednesday, December 7, 2011

Discussion of Field Test Result

Formalex reduced the concentration of formaldehyde in the 10% NBF waste by approximately 85-
The ten wastes used in the testing exhibited LC50
concentrations before treatment of >500 mg/L, which
is less toxic than the hazardous waste criterion. These test results were not intended to establish a
hazardous waste classification for the 10% NBF wastestreams. It is recognized that the toxicity may
vary within and between laboratories. Many health care facilities classify and manage their 10% NBF
wastes as hazardous in CA. Only limited data has been provided to DTSC regarding testing of other
10% NBF samples for comparison to the acute aquatic 96-hour LC50
hazardous waste criterion of Title
22 CCR section 66261.24(a)(6). Some data received by DTSC from generators indicates that the
wastes may be hazardous in some cases. Each generator of 10% NBF wastes should test their wastes
for hazardous waste classification and manage them accordingly.
After treatment with Formalex, about one-half the wastes were more toxic than before treatment and
more toxic than the hazardous waste threshold, when tested using the Standard Method specified in
Title 22 CCR section 66261.24(a)(6). This standard method shakes an aliquot of the wastes with
water to homogenize them prior to adding the waste to the fish tanks. When the method was modified
to test the waste with less shaking, the wastes were all >750 mg/L after treatment.
The toxicity of the post-treatment wastes could not be determined from a visual inspection of the
treated wastes. Wastes with large amounts of precipitate, as well as wastes with little or no precipitate
were found to be toxic (LC50
<500 mg/L) in some cases. For wastes treated with Formalex, the
toxicity of the waste after treatment, and whether the waste would meet a hazardous waste criterion
after treatment, could not be established using the HACH test kit recommended by the Formalex
The Formalex technology is a proprietary formulation based on the acid-catalyzed condensation
reactions of urea with formaldehyde. The mechanism of toxicity of wastes treated with Formalex isunknown. A consideration of potential chemical or physiological mechanism of toxicity was beyond the
scope of the evaluation. An open-ended research project would be required to develop and test
alternative hypotheses. It is not obvious what requirements could be placed on the technology to
ensure that it would be safe and effective when used at health care facilities.
The post-treatment pH values of the Formalex treated wastes were in the range of pH 3.5 – 4.1. Local
POTWs may require neutralization of such wastes before disposal to the sanitary sewer system.
One pre-treatment sample had an anomalously low pH. The low pH of this sample (sample 391, pH
1.5) did not affect the toxicity of the pre-treatment waste or the ability of the technologies to treat the
formaldehyde in the waste. The post-treatment formaldehyde concentrations for this sample were
similar to those for the other samples. The post-treatment toxicity for this sample was >750 mg/L after
What the Data Show. The data show that, before treatment, all ten wastes were slightly less toxic than
the hazardous waste threshold. After treatment with Formalex, about one-half of the samples in each
batch were more toxic after treatment than before treatment, and more toxic than the
hazardous waste threshold.
The increased toxicity for the Formalex treated wastes may depend on the conditions under which the
toxicity test was performed. When the toxicity test was performed under the modified procedures
(without homogenization of the waste) the waste was less toxic. The toxicity does not appear to
depend on how rapidly the reaction occurs (precipitate forms) or how much precipitate is generated.
To investigate the toxicological mechanism, or how changes in waste management practices could
increase or decrease the toxicity, would require an extensive, open-ended research project. This is
beyond the scope of the program. In the absence of an understanding of the reasons for the varying
toxicities, DTSC is unable to specify operating conditions under which it is confident that the
technologies can be used safely and effectively.
Other problems with the Formalex technology. HML staff found the instructions to be unclear. The
product is not supplied with a Lot Number or expiration date. A test kit provided with the technology
for determining treatment completion is ineffective at measuring formaldehyde concentration in the
wastes. The instructions state a 30 – 90 minute time for the reaction mixture to turn cloudy, and that
treatment is complete when the precipitate settles to the bottom of the container. HML found that some
of the samples required >4 hours for the solution to turn cloudy, and that the precipitate continued to
settle for in excess of 24 – 48 hours.

No comments:

Post a Comment