Products

 

TMT 15® is being used in both the Scrubber Slurry and Wastewater for Mercury Removal

 

We have been generating a weekly discussion of use of chemicals in the scrubber slurry to capture the mercury and more importantly prevent it from being re-emitted. John Tarabocchia of Degussa Corporation has weighed in as follows.

 

“The comments from your source at ALSTOM are mostly correct. But we have some additional information to offer. The use of TMT 15 began at waste-to-energy (WTE) plants but its use has spread to coal-fired plants as well. Mercury removal with TMT is practiced at over 250 plants worldwide. Most often TMT 15 is used to treat the scrubber blowdown stream in a wastewater treatment plant, but recently some plants have shown lower mercury emissions by injecting TMT 15 directly into the scrubbing circuit.

 

Recently Germany has required the installation of continuous monitoring equipment for mercury. As a result, it was discovered that some plants were not able to maintain emissions below the 30 micrograms per normal cubic meter limit. Degussa believes that the problem is a chemical reduction (by SO2) of oxidized mercury to the elemental form with the subsequent re-emission of elemental mercury. By dosing TMT 15 directly into the scrubbing circuit, TMT immediately reacts with oxidized mercury forming a very stable salt.  The TMT/mercury salt cannot be reduced by SO2.  As a result, the gas phase emissions were lowered.  The following figure from an operating plant shows this effect.

 

 

The above data is from a WTE plant. Degussa believes that this phenomenon is occurring at coal-fired power plants as well. The only difference is that the mercury concentrations are lower. Degussa is working with coal-fired power plants in Germany and the U.S. and hopes to provide full scale operating experience in the near future.

 

TMT 15 is a 15 percent by weight aqueous solution of the trisodium salt of trimercapto-s-triazine. TMT 15 is manufactured and sold by Degussa AG (Germany) and is available through Degussa Corporation in North America."