Process for the treatment of waste streams

#In the past, in denitrification of metal nitrates, aluminum nitrate has been added to waste solutions containing nitric acid and metal nitrates, such as sodium nitrate and radioactive salts, for example. In particular, waste solutions containing sodium nitrate have been mixed with aluminum nitrate in a direct kerosene fired bed calciner at about 500° C. In this process, the sodium nitrate and aluminum nitrate are converted to sodium aluminate and nitrogen oxides (commonly referred to as NOx, e.g., NO, NO2, and N2O3) according to the following formula: NaNO3+Al(NO3)3→NaAlO2+4NOx

#Unfortunately, the above process requires a substantial amount of aluminum nitrate and is only about 70 percent effective in denitrifying the metal nitrates. Further, the nitrogen oxides that are produced during the reaction are wet-scrubbed, generating more nitrite/nitrate solution than the process began with. Also, problems of agglomeration have been experienced in the calciner due to melting in the bed. As such, a new process that requires less additive, is more efficient, more effective, less costly and more operationally available is needed in treating waste streams, and particular in treating waste streams including nitrogen-containing compounds such as nitrates, nitrites, and NOx compounds.

#According to one embodiment of the present invention, a waste or gaseous stream comprising nitrogen-containing compounds can be treated by a method including decomposing a carbon-containing additive to form a carbon-containing radical and reducing the nitrogen-containing compounds via reaction with the carbon-containing radical and forming a product stream, the product stream including the reduction products that can include, in various embodiments, nitrogen gas, carbon monoxide and/or carbon dioxide, and carbonate salts. The process can also include feeding the waste stream to a reactor, heating the reactor to a reaction temperature, and feeding the carbon-containing additive to the reactor, where it can decompose to form the carbon-containing radicals.

#A full and enabling disclosure of the present invention, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures in which:

#FIG. 1 is a schematic of one embodiment of a reactor suitable for the process of the present invention;

#FIG. 2 is a schematic of another embodiment of a reactor suitable for the process of the present invention;

#Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

#Reference will now be made in detail to various embodiments of the invention. Each embodiment is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the invention without departing from the teaching and scope thereof, for instance, features illustrated or described as part of one embodiment to yield a still further embodiment derived from the teaching of the invention. Thus, it is intended that the invention cover such derivative modifications and variations to come within the scope of the invention embodiments described herein and their equivalents.

#The invention disclosed herein generally relates to a process for treating waste or gaseous streams. In particular, the disclosed invention is directed to a process for treating waste or gaseous streams that include one or more of a variety of nitrogen-containing compounds such as nitrates, nitrites, and/or NOx compounds.