Frequent readers of this column will remember several previous editions dealing with the issue of cyanide regulations on F006 wastes. Since the U.S. Environmental Protection Agency (EPA) intended to address our grievances on this issue in the Third Third Land Ban regulations, lets revisit the issue and provide what guidance we can.

Initial Response

The EPAs response to comments challenging the accuracy and validity of the existing methods for quantitating total cyanide and cyanide amenable to chlorination was to specify that Method 9012 of SW 846 is to be amended so that a 10-9 sample size and one hr and 15 min of distillation be utilized.

"The Agency is aware that analytical problems exist for measuring total and amenable cyanides in non-wastewaters. The Agency believes that these problems exist because there is no specific sample size or distillation time specified in Method 9012."

For unknown reasons, the EPA addressed only Method 9012, which is an automated technique. Many laboratories have no automated techniques and use Method 9010, which is similar. We hope to be able to clarify this apparent oversight in the near future.

To illustrate that the EPA has yet to go a long way toward really solving the analytical problems of Method 9012, lets look at some of the details of the procedure.

Selected Excerpts of Method 9012 1.0 Scope and Application

1.1 Method 9012 is used todetermine the concentration of inorganic cyanide m an aqueous waste or leachate. Method 9012 is not intended to determine if a waste is hazardous by characteristic of reactivity.

3.0 Interferences

3.2 Sulfides adversely affect the colorimetric procedures. Samples that contain hydrogen sulfide, metal sulfides or other compounds that may produce hydrogen sulfide during distillation should be treated by addition of bismuth nitrate prior to distillation.

3.3 High results may be obtained for samples that contain nitrate and/or nitrite.

7.0 Procedure

7.2.6 Heat the solution to boiling. Reflux for 1 hr. Turn off heat and continue the airflow for at least 15 min.

7.5 Standard curve for samples with sulfide.

7.5.1 All standards must be distilled in the same manner as the samples. A minimum of three standards shall be distilled.

9.0 Method Performance

9.1 Precision and accuracy data are not available at this time.

10.0 References

(Four references dealing with WATER are listed.)

Confusing the Issue

The above excerpts illustrate that the EPA has NOT corrected the analytical problems associated with the determination of cyanides in solid wastes. Method 9012 is and was clearly intended for the analysis of aqueous waste and leachate.

Method 9012 indicates that sulfide adversely affects the procedure (usually providing high analytical results.) Sulfides are almost always present in F006 wastes because they are often used as purifiers in plating and are often added on purpose to clarification systems to improve metal removal .

The bismuth nitrate treatment assumes the sulfide is a dissolved specie, not a solid. The efficacy of adding bismuth nitrate to a solid waste containing sulfide has never, to the best of my knowledge, been studied. Furthermore, requiring the addition of one interference (nitrate) to compensate for another (sulfide) does not appear to be a logical choice of remediation.

Contrary to statements made by the EPA in the Third Third regulations, the method clearly states what the EPA calls the "distillation time" in paragraph 7.2.6asa reflux of one hr plus 15 min with the heat turned off. Apparently, the EPA is not familiar with its own procedure.

Method 9012 has no data on the reproducibility, yet the cyanide amenable to chlorination results one obtains are totally dependent upon this reproducibility. For example, a waste that contains 500 mg/Kg of total cyanide can be found to have 50 mg/Kg of cyanide amenable to chlorination totally as a result of the poor reproducibility of the method! The only data we have been able to obtain on the reproducibility of procedures similar to Method 9012 is a study commissioned by the EPA on the cyanide amenable to chlorination procedure on wastewater (referenced in previous A&C articles). This study concluded that under the best of circumstances, with the best and most experienced analyst, a reproducibility of +10 percent can be obtained. It concluded by recommending the abandonment of the existing cyanide amenable to chlorination procedure in favor of one that does not involve subtracting the results of two refluxes, such as is called for in Method 9012!

The bottom line is that the EPA "fixed" only one small problem associated with the total cyanide procedure. By fixing the sample size, labs may find closer agreement on total cyanide results on samples free of sulfide. However, severe problems with sulfide-containing samples and the procedure for amenable cyanide remain.

The EPA did not address problems with the cyanide amenable to chlorination procedure at all. It only acknowledged that the procedure has problems.

Suggestions

If your waste complies with total cyanide, but fails the 30 mg/Kg amenable to chlorination limit, be sure to have the laboratory perform sufficient repetitions of the analysis before you accept the result. Chances are its the procedure that is failing, not your waste.

If your waste contains a lot of sulfide, be sure to warn the laboratory that personnel will need to make special efforts to compensate for the sulfide or they will probably get high test results. Sulfide scrubbing of the gas stream from the reflux may be required to adequately treat this h1terference because bismuth nitrate does not work well on solid sulfides. Laboratories modifying Method 9012 in such ways must obtain approval from the EPA.

Light at the End Of the Tunnel

There is hope. We have seen copies of internal memos/letters from within the EPA acknowledging the problems with the analytical procedure and proposing to study them.

In response to previous articles describing the difficulty of removing iron cyanide from F006 wastes and calling for anyone to provide alternative methods of treatment, we received information on an ion exchange process that selectively removes dissolved ferri-ferrocyanides. The information was provided by Dr. Joseph M. Ragosta, vice president of marketing at Bio-Recovery Systems. Dr. Ragosta suggested using such an ion exchange system after chlorination.

Since the resin might be clogged by solids generated in the chlorination system, it may be more beneficial to use the ion exchange resin before chlorination. We are not aware of anyone using ion exchange in this fashion; but if anyone has experience with such a process, please contact me. Our thanks to Dr. Ragosta for his contribution.